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Feeding exogenous enzymes has the potential to increase the digestibility of nutrients and modify rumen fermentation in diets for feedlot cattle, on the other hand, the effect of the inclusion of corn ethanol co-products on nutrient digestibility is still controversial. We hypothesized that the supplementation of enzyme complex improves nutrient digestibility and increases ruminal pH of feedlot cattle receiving a finishing diet and the inclusion of DFS (corn dry bran/fiber plus distillers solubles) has no effect on rumen fermentation and nutrients digestibility. The objective of this study was to evaluate the use of doses of multicarbohydrase complexes and the inclusion of DFS on nutrient digestibility and rumen fermentation. Ruminally cannulated Nellore steers [n = 30; Initial body weight (BW) = 250 kg] were used in a randomized complete block design in a 2 × 3 factorial arrangement. Factor 1 was defined by the inclusion of DFS [15% or 45% of dry matter (DM)], and factor 2 was the doses of multicarbohydrase complexes (0, 0.75 and 1.0 g/10 kg of DM). The diets contained 8.5% sugar cane bagasse, 44 or 73% ground flint corn, 15 or 45% DFS, 0.5 or 1.5% urea and 2% mineral mix plus monensin with the respective enzyme complex doses. The digestibility assessment was carried out based on the assessment of nutrient consumption (offered and non-consumed feed) and total feces production on d 18 to 22 of the study. Ruminal fluid collection was carried out on d 23 of the study, every 3 h, and samples were analyzed to determine ruminal fluid pH, volatile fatty acids (VFA) proportion and ammonia nitrogen concentration. Orthogonal contrasts were performed to evaluate the effects of enzyme complex doses with a significance level of 5%. Two contrasts were tested to compare: 1) 0 g of enzyme vs. inclusion of enzyme, and 2) 0.75 g of enzyme vs. 1.0 g. There was an interaction (P ≤ 0.05) for protein digestibility. The inclusion of multicarbohydrase complexes increased crude protein (CP) digestibility in diets with 45% DFS, with no effect on diets containing 15% DFS. Feeding the enzyme complex increased (P ≤ 0.05) the ether extract digestibility. Feeding 45 vs 15% DFS had no effect on the digestibility of nutrients (P ≥ 0.05). There was no DFS inclusion and doses of enzymes interaction for ruminal fermentation variables. The DFS inclusion did not affect the VFA and ruminal ammonia; however, the inclusion of 45% DFS increased the ruminal pH (6.40 vs. 6.23). The doses of multicarbohydrase complexes did not affect the ruminal pH, VFA and ammonia concentration; however, decreased the acetate:propionate ratio. In conclusion, the enzyme complex had minor effects on nutrient digestibility but improved rumen fermentation, while feeding 45% DFS in the diet had no effect on nutrient digestibility and increased rumen pH. [ABSTRACT FROM AUTHOR]

Considering the growing accessibility of dried distillers grains with solubles (DDGS) in Brazil, coupled with the limited research examining its integration into conventional confinement diets in the southeast region, comprising ingredients such as flint corn, citrus pulp, and whole cottonseed, there is a clear imperative for conducting studies to deter- mine optimal inclusion levels of this product in such diets. The objective of the study was to compare the performance (experiment 1) and metabolism (experiment 2) of Nellore bulls finished with diets containing 0, 10, 20, 30, or 40% DDGS (% DM) in total replacement of whole cottonseed and partial replacement of ground flint corn and citrus pulp. In experiment 1, Nellore bulls [n = 368; body weight (BW) = 420 ± 30 kg] were used, allocated in 60 experimental pens for 125 d (n = 12 pens per treatment), evaluating variables such as dry matter intake, average daily gain (ADG), feed efficiency, observed net energy (NE) for maintenance and gain, and carcass characteristics. In experiment 2, rumen-cannulated Nellore bulls (n = 30; BW = 503 ± 46) were kept in individual pens for 21 d (n = 6 animals per treatment), evaluating ruminal parameters (proportion of short-chain fatty acids, ammonia concentration, ruminal pH) and apparent digestibility of nutrients in the total tract. The experimental design adopted was randomized blocks, and the data were analyzed using R v. 4.3.1 (R Core Team, 2023). Linear increases were observed in carcass adjusted final BW (P = 0.013), carcass adjusted ADG (P = 0.024), carcass adjusted feed efficiency (P = 0.0003), hot carcass weight (P = 0.0004), and dressing percentage (P < 0.0001) with the incremental inclusion of DDGS in the diets (Table 1). For every 10-percentage unit inclusion in these type of diets, hot carcass weight is increased by 2.56 kg. Additionally, the inclusion of DDGS resulted in linear increases in observed NE for maintenance (P = 0.001) and NE for gain (P = 0.001), calculated according to Zinn and Shen (1998). Digestibility out- comes, determined through the difference of nutrients present in the consumed diet and in the feces, exhibited linearly decreasing effects with the escalating inclusion of DDGS for dry matter (P = 0.004), organic matter (P = 0.004), neutral detergent fiber (P = 0.01), acid detergent fiber (P = 0.04), and total digestible nutrients (P = 0.004). We also observed linear increases for isobutyrate (P = 0.004) and isovalerate (P = 0.002) as the DDGS level in the diet increased. The 40% DDGS diet exhibited 0.6 mmol/100 mol and 0.7 mmol/100 mol more of isobutyrate and isovalerate, respectively, compared with the 0% DDGS diet. In summary, a high inclusion of DDGS emerges as a viable alternative in the nutrition of Bos indicus cattle fed diets containing ground flint corn and citrus pulp, manifesting significant improvements in performance and carcass quality. [ABSTRACT FROM AUTHOR]

In ruminant animals, the use of molasses has benefits related to improved voluntary intake and increased production of short-chain fatty acids (SCFA) in the rumen, especially butyrate. Butyrate is closely related to gastrointestinal tract health, as it may contribute to the increase in the absorption area of the ruminal epithelium and improve the utilization of diet components, resulting in improved voluntary intake and immune response capacity in stressful situations, such as weaning. Hence, our objective was to assess the effect of sugar cane molasses on rumen fermentation characteristics in young beef finishing heifers. Newly weaned Nellore × Red Angus heifers (n = 12) averaging 238 ± 5.1 kg body weight (BW), were used. All heifers were housed in individual pens with concrete floors, covered feeders, and drinkers. The basal diet was 50 % concentrate, and consisted of corn silage, sorghum silage, ground corn, soybean meal, urea, and a mineral premix. The diet was provided twice daily at 0700 and 1600 h, allowing up to 10% in orts (as fed). The following treatments were evaluated: control (no addition of powdered molasses) or addition of 50 g/kg of diet [dry matter (DM) basis] of powdered molasses. The experiment lasted for a total of 80 d, including a 14-d adaptation period. On d 68 and 76, rumen fluid samples were collected both before and 4 h after the morning feeding using an oral probe coupled to a vacuum pump. The initial fluid samples were discarded to prevent saliva contamination. The rumen fluid was filtered through four layers of cheesecloth, and then pH was measured. Subsequently, samples were taken and stored in an ultra-freezer (-80°C) for subsequent SCFA analysis. The data were subjected to analysis of variance using the GLM procedure of SAS 9.4 (α = 0.05). Providing molasses increased ruminal pH compared with control heifers (P < 0.032). Adding molasses did not affect SCFA concentration (P > 0.90). Conversely, we detected an effect of molasses on SCFA molar proportion. The molar proportion of both acetate (P < 0.013) and butyrate (P < 0.012) were greater in heifers fed molasses than with controls. On the other hand, dietary molasses addition decreased (P < 0.001). the propionate molar proportion. This resulted in an increased (P < 0.002) acetate-to-propionate ratio in heifers fed diets containing molasses. In conclusion, providing sugar cane molasses enhances rumen fermentation characteristics in young beef finishing heifers. [ABSTRACT FROM AUTHOR]

The inclusion of the coproduct dry distil- lers grains plus soluble (DDGS) in the diet of finishing cattle can lead to changes in the nutritional profile of the diets, causing an increase in protein content and a reduction in starch. It is necessary to understand how changes in rumen substrates affect rumen metabolic activity, acids, and enteric methane (CH4) production. Five treatments were used, considering levels of DDGS inclusion in the dry matter (DM) of 1) 0 g/kg of DDGS, 2) 150 g/kg of DDGS, 3) 300 g/kg of DDGS, 4) 450 g/kg DDGS, or 5) 600 g/kg DDGS in finishing diets. The metabolism experiment was conducted with rumen-cannulated Nellore bulls (n = 20) with initial body weight (BW) of 401.8 ± 27.0 kg. The production of short-chain fatty acids (SCFA) and CH4 were determined using the ex-situ ruminal fermentation technique. Rumen content was manually collected from 0, 4, 8 and 12 h post-feeding. The liquid and solid fractions of rumen content were used in four 50 mL penicillin-type flasks per animal. Of the four flasks prepared, two are called “blank” and inactivated in boiling water to stop fermentation, and the other two (microrumen) are incubated in a thermostatic bath, simulating the conditions existing in the rumen of animals (presence of microorganisms, anaerobes, temperature of 39ºC, natural animal saliva, physiological pH) for 30 min. After 30 min, incubated flasks were also inactivated in boiling water to stop fermentation. Subsequently, measurements of the final products of rumen fermentation (SCFA and CH4) were carried out in each bottle. Total rumen emptying was performed to determine the rumen pool of DM. The data will be analyzed in the SAS software, the mean of the treatments will be compared using test of mean and orthogonal contrasts. The declared significance is P ≤ 0.05. The inclusion or levels of DDGS did not affect CH4 production of gּ·kg DM-1ּ·d-1ּ and gּ·kg DM-1ּ d-1ּ (P > 0.05). There was an effect of the treatments on the production of propionate (gּ·kg DM-1ּ d-1ּ; P = 0.0448), with a decreasing linear effect (P = 0.0087) with the increase in the inclusion of DDGS in diet (0; 150; 300; 450; 600 g/kg of DDGS; means 137.20; 160.32; 117.60; 87.09; 91.52 gּ·kg DM-1ּ d-1ּ propionate, respectively). There was no effect of DDGS levels on the production of Acetate, Butyrate, or total SCFAs (gּ·kg DM-1ּ d-1ּ). In summary, DDGS inclusion affects rumen metabolic activity, decreasing propionate production, but does not affect the production of other SCFAs nor CH4 production. [ABSTRACT FROM AUTHOR]

Individually fed fistulated steers [n = 8; body weight (BW) = 410 ± 10 kg] were used to investigate the effects of dietary trace mineral (TM) source on in vitro trace mineral (TM) solubility and TM concentration of rumen bacteria and protozoa. Steers were blocked by BW and sorted into two TM treatment groups. Treatments consisted of 10 mg copper (Cu), 40 mg manganese (Mn), and 60 mg zinc (Zn)/kg DM from either sulfate TM (STM) or hydroxy TM (HTM) sources (n = 4/treatment). Steers were individually housed, and dietary TM treatments were mixed with dried distillers grains and top-dressed daily. Steers were fed a diet formulated to meet the nutrient requirements for a high producing lactating dairy cow for 14 d. Strained rumen fluid (SRF) was obtained on d 15 by squeezing the rumen contents of each steer through 2 layers of cheesecloth. One-half of retained digesta was washed with pre-warmed McDougall’s buffer to remove particle-associated microorganisms (PAO). The SRF and the PAO were then filtered through 8 layers of cheesecloth, separately, and mixed at a ratio of 1:2 (SRF:PAO). The mixture of SRF-PAO from each steer was used to incubate 0.5 g of the basal diet containing either HTM or STM, respectively. The SRF-PAO fluid from each steer was incubated in triplicate with each dietary treatment at 39°C under anaerobic conditions for 24h. After incubation, abomasal digestion was stimulated by adding 1.0 M HCl and 1.5% pepsin. Tubes were then incubated for 2 h at 39°C and centrifuged at 2,000 x g for 15 minutes. Supernatant (2 mL) was removed for soluble TM determination. The pH of solution was then increased to 6.5 by the addition of 3.5% pancreatin in a 1 M NaOH solution and then incubated at 39°C for 2 h. The mixture was centrifuged at 2000 x g to separate the supernatant and digesta fractions for mineral analysis. Protozoal and bacterial fractions were also collected from SRF and PAO for TM analysis. Data were analyzed for a randomized block design using a linear mixed-effect model. There was no feeding tube interaction for all parameters measured, so only main effects are reported. Manganese and Zn concentrations in the digesta within fermentation tube containing HTM were greater (P < 0.02) than STM. Tubes containing HTM had a greater (P < 0.001) soluble Mn concentration than STM after in vitro abomasal digestion. Trace mineral concentration of bacteria and protozoa were similar across treatments. These data may indicate that the TM source may influence TM solubility in the abomasum and intestine, but has no impact on bacterial or protozoal concentrations of Cu, Mn, or Zn. [ABSTRACT FROM AUTHOR]

Ruminal methane (CH4) emission from cattle represents about 2 to 12% gross energy loss and is considered as one of the main contributors to the greenhouse gas emissions by the livestock industry. Recent multiple lines of research indicated that maternal gut microbiome may influence offspring ruminal CH4 emission phenotype via potential influence on fetal programming and transmission of methanogens from the dam to calf perinatally. Our objective was to evaluate the effects of altering maternal microbiota via feeding high forage (HF) and high concentrate (HC) diets during the entire gestation on the maternal ruminal CH4 emissions in beef heifers. For this, Crossbred replacement beef heifers (n = 61) bred with male sexed semen were randomly assigned into two groups and were fed either a high forage (75% forage:25% concentrate; HF, n = 29) or high concentrate (25% forage:75% concentrate; HC, n = 32) diet with limited feed intake to gain 0.45 kg/d during the gestation. Individual feed intake was monitored and body weight (BW) were measured bi-weekly and diet deliveries were adjusted to ensure the target BW gain. A subset of pregnant heifers (n = 10 per treatment group) was harvested at 180 d of gestation. Ruminal fluid was collected by stomach tubing on d 180 (20 heifers slaughtered), d 238 of gestation, and at the postpartum (within 3 h of calving). The ruminal fluid was placed in 15 mL falcon tube, kept in a warm thermos and immediate processing for the in vitro CH4 production assay. About 12.5 mL of ruminal fluid was placed into separate 120 mL serum bottles each containing 0.62g of feed (HC or HF diet) and 50 mL of McDougall buffer under CO2 infusion before the bottle sealed with stoppers. The cultures were incubated at 39°C for 24h. Immediately after incubation, total biogas production, headspace CH4 concentration (using Gas chromatography), and pH of the 24 h culture was measured. Overall, the mean total volume of gas produced over 24 h was not statistically different (P > 0.05) between HF and HC heifers at any of the day measured, although it was numerically greater on d 238 (219 vs. 197 mL) and at postpartum (246 vs. 219 mL) in HC than HF heifers. Methane concentration in per milliliter gas was ranged between 13.3 and 16.3% but was not different between HF and HC heifers on any of the day evaluated (P > 0.05). Total volume of CH4 gas produced over 24 h was tended (P = 0.067) to be greater in HC heifers on d 238 (37.5 vs. 25. 7 mL). The culture pH from the ruminal fluid of HC heifers was less on d 238 (6.08 vs. 6.57) and at postpartum (P < 0.05). Overall, in vitro ruminal CH4 was not different in the ruminal fluid of HF and HC pregnant heifers. [ABSTRACT FROM AUTHOR]

The nutritional value of grasslands declines as the season progresses, negatively impacting cattle nutrition. Protein supplementation may reverse this trend, although high rates of ruminal proteolysis reduce the efficiency of N utilization. Tannins decrease protein degradability in the rumen, although they are also plant defenses with potential to influence animal behavior. The objective of this study was to determine in proteinsupplemented cows grazing meadow bromegrass (MB) the influence of tannins on blood urea nitrogen (BUN), and on behavioral levels of activity. Twenty-four Black Angus cow [body weight (BW) = 614 ± 20 kg]-calf (BW = 244 ± 4 Kg) pairs were allotted to six 9-acre paddocks (4 pairs/paddock); animals in the Control (Ctrl; n = 3) and Tannin treatments (TT; n = 3) grazed meadow bromegrass (MB) and had a supplement of dried distillers grains with solubles (DDGS; (1 kg. cow- 1. d-1), with the addition of a mix of condensed (2/3): hydrolizable tannins(1/3; SilvaTeam) at 0.4% of the diet for TT. Grazing occurred from July to September 2023 with four experimental periods of 15 d each, the first being the adaptation period (no tannins; Baseline). Data were analyzed as a mixed-effects model with repeated measures and paddock as the experimental unit. Cows were fitted with accelerometers on their left back leg to determine activity, and blood samples were collected from all animals at the end of each period to estimate BUN. Representative samples of grass and supplement were collected from each period and paddock and analyzed for CP and fiber content. Herbage availability (DM basis) in each paddock was assessed before and post-grazing during each period using a rising plate meter and calibration curves. neutral detergent fiber (NDF) (62.9 to 65.1 ± 0.5%) and and acid detergent fiber (ADF) (38.7 to 43.9 ± 0.3%) increased, whereas CP (6.8 to 3.9 ± 0.1%) declined from Period 1 to 4 (P < 0.05). Initial biomass was 5,272 ± 211 Kg/ ha and it declined after grazing (Period 4) to 2,319 ± 94 Kg/ha (P < 0.05) with no differences between treatments (P > 0.05). No differences between treatments were observed on motion index, number of steps taken per day, and the proportional percentage of time cows spent standing (9,379 ± 740, 2,611 ± 300, and 54.9 ± 0.02%, respectively; P > 0.05), suggesting that cows in TT did not invest extra time in searching activities or resting relative to Ctrl. It was only detected a greater percentage of transitions from lying to standing in TT than in Ctrl (7 to 3.4 ± 0.003%; P < 0.001). Values for BUN did not differ between treatments (P > 0.05), although they declined from Baseline to Period 4 by 28 % (8.2 to 5.9 ± 0.2mg/dL) in TT and by 2.6 % (5.75 to 5.6 ± 0.01 mg/dL) in Ctrl (P < 0.05). These results suggest that the addition of low levels of tannins to a protein supplement in cows grazing a low-quality grass diet reduces ruminal proteolysis without adversely influencing biomass removal or animals’ levels of activity. [ABSTRACT FROM AUTHOR]

This review delves into the intricate realm of ruminal microbes, shedding light on their complexity beyond previously recognized dimensions. Existing publications have probed the essential facets of these microorganisms on a finer scale than previously acknowledged. Mathematical models have emerged to simulate the behavior of approximately 200 distinct bacterial species, 25 genera of ciliate protozoa, and five genera of anaerobic fungi, constituting about 10% of the total viable bacteria in the rumen. However, the expansive diversity and density of rumen microbes challenge the complete characterization of species or genera in relation to substrates or end products. Consequently, continuous revision and re-engineering of mathematical models become imperative. In the context of ruminants, prevalent models often categorize bacteria into fiber-fermenting and nonfiber-fermenting groups. An additional subgroup featuring hyper-ammoniaproducing bacteria has been proposed, but its explicit integration into nutrition models remains unexplored. Furthermore, incorporating a more mechanistic evaluation of protozoa and fungal growth may be warranted to improve nutrition models. The time horizon and intervals at which models are constructed present another critical consideration, with feed efficiency variations among ruminants believed to be closely tied to differences in the ruminal microbiota. Addressing immediate concerns, this review underscores the need for a comprehensive exploration of factors influencing microbial growth in the rumen. Several indices have been suggested and adopted to predict microbial efficiencies, but they may provide simplification for practical application. Thus, a mechanistic approach should be considered to remove dependencies between estimates and improve predictive accuracy and precision. While artificial intelligence holds promise in elucidating gaps within empirical and mechanistic models, the generation of accurate, vetted datasets is paramount. Furthermore, this review posits that factors such as recycled nitrogen, endotoxins, and microbial population dynamics (i.e., cross-feeding and competition) may be limiting our understanding of microbial growth, suggesting the necessity of modeling these intricacies concurrently to achieve a more nuanced comprehension. This multifaceted approach aims to propel the understanding of ruminal microbial dynamics into new frontiers, paving the way for more informed and effective modeling in the future. [ABSTRACT FROM AUTHOR]

Residual feed intake (RFI), a metric of feed efficiency, is moderately heritable and minimally associated with body size and productivity, making it an ideal trait for investigation as a selection criterion to improve feed efficiency of growing cattle. The objective of this research was to characterize the inter-animal variation in biological processes of growing cattle selected to be divergent in RFI. Holstein heifers [n = 55; body weight (BW) = 351 ± 64 kg) with low- (n = 29) or high- (n = 26) genomically enhanced RFI (RFIg) were selected from a contemporary group of 453 heifers. Heifers were assigned to 1 of 2 pens, equipped with electronic feed bunks and a GreenFeed gaseous-exchange measurement system. Individual dry matter intake (DMI) and feeding behavior data were collected for 84-d. Body weight was measured weekly, and spot fecal samples collected at weighing. Phenotypic RFI (RFIp) was calculated as the residual from regression of DMI on ADG and mid-test BW0.75. On d 70 of the study a rumen fluid sample was collected via esophageal tubing. Blood samples were collected and analyzed for complete blood count (CBC). A mixed model including the fixed effect of RFIg classification and random effect of pen was used to evaluate the effect of RFIg classification on response variables. There were no differences (P > 0.05) in BW and ADG for heifers with divergent RFIg; however, low RFIg heifers consumed 7.5% less (P < 0.05) feed per day. Consequently, low RFIg heifers exhibited a more favorable (P < 0.05) RFIp (-0.188 vs 0.211 kg/d, respectively). Low RFIg heifers exhibited more favorable feeding behavior, with 8.7% fewer (P < 0.05) bunk visit events per day and an 11.2% slower (P ≤ 0.05) eating rate. Low RFIg heifers had 12.5% greater (P < 0.05) total rumen volatile fatty acid concentrations than high RFIg heifers, indicating potentially enhanced microbial fermentation and improved efficiency of feed utilization. Low RFIg heifers had 8.2% less (P < 0.05) methane emissions (g/d), 6.3% less (P < 0.05) carbon dioxide production (g/d), and 6.1% less (P < 0.05) heat production (Mcal/d) calculated according to Brouwer (1965) than high RFIg heifers. Dry matter digestibility did not differ (P > 0.05) between heifers with divergent RFIg. Overall, heifers selected to be more feed efficient exhibited more favorable energy efficiencies and feed efficiency phenotypes. To quantify the variation in RFIg explained by feeding behavior, gas flux, digestibility and rumen fermentation, and CBC partial least squares regression models were developed. Feeding behavior accounted for the largest proportion of variation in RFIg (28.8%). Upon sequential addition of gas flux, digestibility and rumen fermentation, and CBC to feeding behavior, 56.3% of the variation in RFIg was accounted for. Identifying the magnitude at which metabolic processes influence inter-animal variation in efficiency of nutrient utilization provides opportunities to discover valuable candidate biomarkers for selection of more feed efficient cattle. [ABSTRACT FROM AUTHOR]

We examined the effects of a blend of Saccharomyces cerevisiae, multiple live probiotic bacteria and their fermentation products on performance, health, and the ruminal bacterial community of newly weaned beef steers during a 56-d receiving period. Newly weaned Angus crossbred steers [n = 40; 221 ± 25.6 kg body weight (BW); 180 ± 17 d of age] were stratified by BW into four pens (10 steers per pen) such that each pen had a similar average BW at the beginning of the experiment. The pens were randomly assigned to receive a corn silage basal diet (CON; n = 20) or the basal diet supplemented with 9 g·steer-1·d-1of PRO feed additive (PRO; n = 20). The PRO additive is a blend of Saccharomyces cerevisiae and the fermentation products of Enterococcus faecium, Bacillus licheniformis, Bacillus subtilis, Lactobacillus animalis, Propionibacterium freudenreichii. The DMI and water consumed were monitored using the GrowSafe intake nodes and custom flow meters, respectively. Body weights were recorded weekly to calculate average daily gain (ADG). Before morning feeding, 10 mL of blood was taken from each steer on d 0 to 7, and thereafter weekly for analyses of immune cells, plasma glucose and NEFAs. On d 56, rumen fluid samples (200 mL each) were collected from all the steers for microbiome analysis. Over the 56-d receiving period, the supplemental PRO had no effects on DMI, water intake, or ADG. However, compared with CON, beef steers fed supplemental PRO tended to have greater ADG (P = 0.08) and BW (P = 0.07) during the first 14 d of the study. There was a treatment × day interaction (P ≤ 0.05) for WBC, neutrophils and monocytes over the 56 d such that beef steers fed supplemental PRO had decreased blood concentrations on certain days during the first 7 d after weaning, indicating reduced inflammation or stress response. The results of the rumen microbiome analysis revealed that the relative abundance of complex fiber degrading or obligate proton-reducing bacterial genera such as Bacteroides, Ruminococcus gauvreauii group, Desulfovibrio, Syntrophococcus, and Acetitomaculum were greater (P ≤ 0.05) in beef steers fed supplemental PRO compared with CON. This study demonstrated that dietary supplementation of PRO improved the growth performance, reduced stress or inflammatory response during the initial days after weaning and altered the ruminal bacterial community towards increased relative abundance of bacterial genera associated with improved rumen function. [ABSTRACT FROM AUTHOR]

Forage comprises the majority of beef cattle diets globally, and its quality can vary. Supplementation presents a significant opportunity to improve the efficiency of production. Supplementation has been shown to increase ruminally available nitrogen, improve forage utilization, and reduce livestock methane (CH4) emissions. However, corresponding effects of supplementation on gene expression of rumen microbiota, in particular metabolic pathways involved in methanogenesis, have yet to be studied. This study aimed to evaluate the effect of supplement composition before and after feeding on rumen archaeal and bacterial gene expression in steers consuming a lowquality forage diet. Ruminal samples were collected from five ruminally cannulated Angus steers [body weight (BW) = 375 ± 45 kg] used in a 4 × 4 Latin square fed a basal diet of King Ranch Bluestem Hay (3.5% CP, 73% NDF), and one of four isonitrogenous (130 mg N/ kg BW) supplements. Steers provided the two most divergent supplements (2% starch, 43% CP; 56% starch, 21% CP) were used for metatranscriptomic analysis. Rumen fluid samples were collected via rumen cannula 0 and 4 h post-feeding. Total RNA was extracted and sequenced. Differentially expressed genes (DEGs) were identified and functionally annotated. Pathway enrichment analysis was completed to determine enriched pathways (broad metabolic pathways) and modules (specific metabolic reactions). Only main effects are presented in this abstract. Archaeal hydrogenotrophic and methylotrophic methanogenesis reactions and tryptophan biosynthesis reactions were upregulated in the 2% starch supplement (P < 0.05). The 2% starch supplement resulted in fewer bacterial total upregulated carbohydrate-active enzymes compared with the 56% starch supplement (957 vs. 1,695 DEGs, respectively; P < 0.05), and an increased proportion of cellulose and hemicellulose-specific enzymes (35 vs. 29%, respectively; P < 0.05). The 56% starch supplement resulted in upregulation of the bacterial 3-Hydroxypropionate bi-cycle reaction (P < 0.05). Collection time exerted a larger effect than supplement composition on both archaeal and bacterial gene expression, with 83% and 63% of DEGs associated with time, respectively (P < 0.05). Archaeal hydrogenotrophic methanogenesis and carbon metabolism were upregulated 4 h post-feeding. In addition, 1,704 bacterial carbohydrate-active enzymes were upregulated 4 h post-feeding, as compared with 975 upregulated at 0 h (P < 0.05). However, these differences in DEGs did not correlate with significantly enriched pathways of bacterial carbohydrate metabolism. These findings demonstrate improvements to low-quality forage utilization, through CP and starch supplementation, can be correlated to relevant changes in gene expression of rumen microbiota. Furthermore, they demonstrate that supplementation influences the expression of methanogenesis reactions, suggesting an opportunity to affect CH4 production. Additional studies quantifying forage utilization, rumen microbiota gene expression and CH4 production are needed to further optimize supplementation strategies for improved efficiency of beef production whilst maintaining or reducing its carbon footprint. [ABSTRACT FROM AUTHOR]

Nutrients derived from ruminal fermentation supply a substantial amount of metabolizable nutrients for ruminants. These include amino acids, carbohydrates, fatty acids, vitamins, and fermentation end products, such as ammonia and volatile fatty acids. Furthermore, ruminal fermentation modifies dietary nutrients in such a way that nutrients reaching the small intestine for absorption may substantially differ from those being consumed in the diet. Therefore, understanding ruminal fermentation kinetics and quantification of nutrients flowing out of the rumen is an important aspect of ruminant nutrition. Accurate quantification of these nutrients, using in vivo experiments, is laborious, costly, and invasive, requiring surgical procedures such as ruminal, abomasal, and intestinal cannulas. To decrease the time and cost of experiments as well as the use of animals, in vitro methodologies are important tools in ruminant nutrition. Therefore, the objectives of this presentation are i) describe different in vitro methodologies, ii) discuss the advantages of in vitro methodologies, iii) discuss shortcomings of in vitro methodologies, and iv) describe potential developments that may improve in vitro methodologies. Having been used for decades, in vitro methodologies such as pure, batch, and continuous cultures have been well documented to investigate a wide array of aspects of nutrition, including the effects of different dietary compositions, individual fermentation end products, and impacts on the microbiome. However, both batch and pure cultures can result in a build-up of end products that may inhibit fermentation. Continuous culture, however, allows for the removal of end products but, similar to pure and batch cultures, is applicable only to ruminal fermentation and cannot provide information regarding intestinal digestion. The dual-flow continuous culture system (DFCC), developed in the 1970s and used by various laboratories in the USA and Europe consists of fermentation vessels of approximately 1.5 L that are capable of simulating ruminal fermentation for periods longer than 10 d. It has been extensively used and evaluated by meta-analyses. When compared with other in vitro methodologies, the DFCC has longer fermentation time, larger volume, and the possibility of sampling from the liquid and the solid flows. When compared with in vivo experiments the DFCC is faster, less costly, less invasive, allows for greater range of treatments, allows for more controlled condition, and isolates ruminal function. Limitations of the DFCC include it does not predict in vivo response, it assumes equal saliva flow and concentration, no effects of intake, no ruminal absorption, less retention of protozoa, possible differences in microbiome, and limited gas emission data. Therefore, while in vitro methodologies provide useful data into the field of ruminant nutrition, some in vitro methodologies are more robust than others. Furthermore, in vivo experiments are still the ideal approach for assessing nutrient utilization and necessary to evaluate animal responses. [ABSTRACT FROM AUTHOR]

This dataset describes the temporal patterns of enteric gas production from cattle in response to ruminal infusions of synthetic bromoform (CHBr3). Four non-lactating, non-pregnant, rumen-fistulated Holstein-Friesian cows (12 yr of age, 781 ± 33 kg body weight) were infused via the rumen fistula with 592 mg CHBr3/d in an aqueous solution for 14 d. The daily dose was divided into 3 equal portions and infused every 8 h over a 24-h period (0545, 1345, and 2145 h). The 7 d following the infusion period served as a recovery period to describe the dynamics of enteric gas production after cessation of infusion. The Greenfeed system was used for enteric gas measurements. Animals had ad libitum access to grass hay and were supplemented with concentrate through the Greenfeed system for the infusion and recovery periods and for the 14-d adaptation period before the infusions. A two-way ANOVA was performed with phase (pre- and post-infusion) as fixed effect and animal as random effect to assess average differences. Preliminary results show a decrease in methane (CH4) production from on average 371 g/d before the infusions to 5 g/d after 14 d of infusions (P < 0.01). Hydrogen (H2) production increased from on average 0.6 g/d before the infusions to 9.0 g/d after 14 d of infusions (P < 0.01). Dry matter intake (DMI) decreased to on average 12.8 kg/d after 14 d of infusions compared with 16.9 kg/d before the infusions (P < 0.01). A four-parameter logistic model was fitted for the response of CH4 (CH4-inf) and H2 (H2-inf) production in the 14 d after the first infusion, and separately for the response of CH4 (CH4-rec) and H2 (H2-rec) production in the 7 d after the last infusion (Table 1). Preliminary results indicate a 95% decrease in CH4-inf from the A-asymptote (small values of x) is reached after approximately 63 h, and a 95% increase in H2-inf from the B-asymptote (large values of x) is reached after approximately 49 h. After the last infusion, the 95% increase in CH4-rec from the B-asymptote is reached after approximately 109 h, and the 95% decrease in H2-rec from the A-asymptote is reached after approximately 112 h. When comparing the respective inflection points (xmid), the recovery of CH4 production took approximately 3 times longer than the decrease. In addition, after 7 d of recovery, CH4 production did not return to the initial levels before the infusion began. The reduced DMI can partially explain this difference in CH4 recovery; however, other factors cannot be excluded. In conclusion, our data suggest that ruminal infusion of 592 mg CHBr3/d for 14 d reduces CH4 production by >95% and the recovery of CH4 production to pre-infusion levels might take longer than 7 d. [ABSTRACT FROM AUTHOR]

Nutrient supplementation is one of largest expenditure in forage-based beef production systems, especially when forage quality is poor or limited. Decreasing supplementation frequency may have a role in improving sustainability by increasing animal performance and minimizing cost of labor and fuel. This study evaluated the impacts of protein supplementation frequency (canola meal pellet; CMP) on animal performance, rumen fermentation, and enteric methane production from beef cattle fed forage-based diet. A total of 60 crossbred backgrounding steers [body weight (BW) = 278 ± 10 kg) was randomly assigned to one of the three treatments (n = 20/treatment): i) control (no CMP supplementation), ii) control + everyday CMP supplementation (0.83 kg/d per steer), and iii) control + every other day supplementation of CMP. The study was comprised of 21 d of adaptation followed by three 21-d periods, with enteric methane measured for 7 d per period. Animals were fed grass hay-based diets once a day at 0800 h and remained on their respective diets throughout the 63-d study. Diets were formulated considering animal BW, feed nutrient density and environmental condition in accordance with the National Academies of Sciences, Engineering and Medicine. Each treatment group was assigned to a pen, with the cattle and diets rotated among pens weekly to allow the animals to access the GreenFeed system stationed in one of the pens for enteric methane measurement. For measurement of rumen fermentation products, three ruminally canulated steers (BW = 350 ± 20 kg) were allocated to the three treatments using a 3 x 3 Latin Square Design with 21-d periods so that one animal received all the treatments over the three experimental periods. Animals were adapted to the treatments for 17 d and rumen samples were collected between d 19 and 21 at 0700 h, 1000h, 1300 h, 1600 h and 1900 h. Data were analyzed using the Mixed procedure of SAS. Relative to the control treatment (9.9 kg/d), DM intake was 4 to 5% greater (P < 0.001) following CMP supplementation regardless of supplementation frequency. Similarly, average daily gain was greater (7 to 11%, P = 0.01) for CPM supplemented treatments as compared with control (1.04 kg/d) irrespective of supplantation frequency. Rumen fermentation was affected by treatments. Total VFA concentration was greater (P = 0.01) for the every other day supplementation of CMP as compared with control and daily supplementation treatments. Conversely, rumen ammonia concentration was not affected by treatments. The control group had greater acetate and reduced propionate molar proportions that resulted in a 5 to 6% greater acetate:propionate ratio (P < 0.01) as compared with the CMP supplemented groups. Enteric methane production (g/d) was greater for the daily CMP supplementation (P = 0.02) while yield (g/kg daily weight gain) was not affected by treatment. Our results indicated that reduction of protein supplementation frequency improved animal performance without negatively impacting rumen fermentation. [ABSTRACT FROM AUTHOR]

The objectives of this study were to 1) evaluate gastrointestinal fermentation characteristics and permeability, and white blood cell concentrations as beef heifers recovered from a feed restriction (FR) challenge, and 2) determine whether post-ruminal provision of a yeast cell wall extract (YCW) modulated responses. Ruminally cannulated beef heifers (n = 8) were used in a 2 × 2 crossover design. Treatments (TRT) included an abomasal infusion of a placebo (PLC; maltodextrin) or YCW derived from Saccharomyces cerevisiae (2 g/dose) infused at 0600 and 1800 h. Heifers were subject to 5-d of FR (offering 30% of ad libitum DMI) followed by five 5-d recovery phases (REC1, REC2, REC3, REC4, and REC5). Daily DMI, and rumen, fecal, and blood samples were collected on d 5 of FR, REC1, REC3, and REC5 with an additional collection on d 2 of REC1. Total gastrointestinal and post-ruminal permeability were measured using a ruminal dose of Cr-EDTA and an abomasal dose of Co-EDTA, respectively, during FR, REC1, REC3, and REC5 with concurrent urine collection. Data were analyzed to determine the effects of YCW provision, day, and the 2-way interaction. There were no TRT or TRT×day effects for any variables except DMI (interaction, P = 0.04), where DMI did not differ during the FR challenge; however, heifers provided YCW had a greater increase by REC1 compared with PLC heifers without any means differing. DMI progressively increased from FR, to REC1, REC2, and REC5. Ruminal acetate concentration increased (P < 0.01) from FR (45.4 mmol/L) to REC1 d5 (60.1 mmol/L) and increased further to REC3 (67.3 mmol/L) with no change thereafter (68.3 mmol/L in REC5). Ruminal propionate concentration increased (P < 0.01) from FR (14.5 mmol/L) to REC1 d2 (27.7 mmol/L) and was not different thereafter. Similarly, butyrate concentration increased (P < 0.01) from FR (7.9 mmol/L) to REC1 (d 5; 15.0 mmol/L) and was not different thereafter. Fecal acetate, propionate, and butyrate concentrations were not affected by day (P ≥ 0.12). Total gastrointestinal and post-ruminal permeability were greatest during FR (P < 0.01; 2.6% and 2.2% of the infused marker was excreted in urine, respectively) and decreased to 1.6% and 1.1%, respectively, in REC3 followed by an increase in REC5 for total (2.0% of infused) but not post-ruminal (1.0% of infused) permeability. The concentration of neutrophils (P < 0.01) was greatest on REC1 d2 (4.84 ×106 μmol/mL) and eosinophil concentration (P < 0.01) was greatest during FR (0.53 ×106 μmol/mL), least on d 2 of REC1 and increased on d 5 of REC1 but was not different thereafter. WBC (P < 0.01) gradually decreased (P = 0.02) from FR and REC1 d2 to REC3 and REC5. Post-ruminal provision of YCW may accelerate increases in DMI early in the recovery from FR, yet treatment did not modulate ruminal or fecal SCFA, blood concentrations, or gastrointestinal permeability. [ABSTRACT FROM AUTHOR]

The objective of these studies was to evaluate effects of increasing hybrid rye silage (HRS; harvested at boot stage in Study 1 and soft-dough in Study 2) inclusion as a replacement for barley silage (BS; harvested at soft-dough stage) on dry matter intake (DMI), ruminal fermentation, and growth performance of growing beef cattle. In Study 1, ruminally cannulated Hereford × Simmental heifers (n = 8) with an initial body weight (BW) of 519 ± 25.8 kg were used in a replicated 4 × 4 Latin square design with 28-d periods including 21 d of dietary adaptation and 7 d of data and sample collection to assess DMI and ruminal fermentation. Treatments included a control diet (DM basis) that contained 59.62% BS, 38.60% barley grain, and 1.78% of a vitamin and mineral supplement. Hybrid rye silage replaced 33, 67, and 100% of the BS on a DM basis. In Study 2, steers (n = 384; BW = 343 ± 20.2 kg) were stratified by BW and allocated to 32 pens in a randomized complete block design over 2 yr (4 pens/treatment/yr) to evaluate DMI, growth, and gain:feed (G:F). Steers were fed similar diets as Study 1 for 84 d in both years. In Study 1, increasing HRS linearly (P < 0.01) decreased DMI from 12.0 to 9.2 kg/d, and linearly increased (P = 0.02) water intake from 18.6 to 22.5 L/d. Increasing HRS linearly increased mean (P < 0.01) and minimum ruminal pH (P < 0.01). There was no effect of HRS inclusion on total shortchain fatty acid concentration (P = 0.46) in ruminal fluid, but the molar proportion of acetate linearly (P < 0.01) increased while propionate and butyrate linearly decreased (P < 0.01, and < 0.01, respectively) with increasing HRS inclusion. Moreover, increasing HRS inclusion linearly increased the molar proportions of isobutyrate and valerate (P = 0.06, and < 0.01, respectively) while caproate decreased linearly (P = 0.02). The ammonia-N concentration linearly increased with increasing HRS inclusion. In Study 2, DMI was 9.23, 9.10, 8.82, 8.08 kg/d (quadratic, P = 0.02) for diets containing 0, 33, 67, and 100% HRS, respectively. Likewise, ADG decreased (1.45, 1.36, 1.30, 1.08 kg/d; quadratic P < 0.01) as HRS inclusion increased and G:F ratio decreased linearly (P < 0.01) from 0.158 with 0% HRS to 0.134 g/kg when diets contained 100% HRS. Final BW was 462, 456, 450, and 432 kg when HRS was included at 0, 33, 67, and 100% of the silage, respectively (quadratic, P = 0.04). In conclusion, replacing BS with increasing proportions of HRS reduced DMI resulting in greater ruminal pH, altered molar proportions of individual SCFA, and reduced growth performance and G:F during the growing phase. [ABSTRACT FROM AUTHOR]

A dose-response experiment was designed to examine the effect of 3-nitrooxypropanol (3-NOP) on methane (CH4) emissions, rumen function and performance of feedlot cattle fed a tempered barley-based diet with canola oil. Twenty Angus steers of initial body weight (BW) of 356 ± 14.4 kg were allocated in a randomized complete block design. Initial BW was used as the blocking criterion. Cattle were housed in individual indoor pens for 112 d, including the first 21 d of adaptation followed by a 90-d finishing period when five different 3-NOP inclusion rates were compared: 0 mg/kg dry matter (DM; control), 50 mg/kg DM, 75 mg/kg DM, 100 mg/kg DM, and 125 mg/kg DM. Daily CH4 production was measured on day 7 (last day of starter diet), day 14 (last day of the first intermediate diet), and day 21 (last day of the second intermediate diet) of the adaptation period and on days 28, 49, 70, 91, and 112 of the finisher period using open circuit respiration chambers. Rumen digesta samples were collected from each steer on the day prior to chamber measurement postfeeding, and prefeeding on the day after the chamber measurement, for determination of rumen volatile fatty acids (VFA), ammonium-N, protozoa enumeration, pH, and reduction potential. Dry matter intake (DMI) was recorded daily and BW weekly. Data were analyzed in a mixed model including period, 3-NOP dose and their interaction as fixed effects, and block as a random effect. Our results demonstrated both a linear and quadratic (decreasing rate of change) effect on CH4 production (g/d) and CH4 yield (g/kg DMI) as 3-NOP dose increased (P < 0.01). The achieved mitigation for CH4 yield in our study ranged from approximately 65.5% up to 87.6% relative to control steers fed a finishing feedlot diet. Our results revealed that 3-NOP dose did not alter rumen fermentation parameters such as ammonium-N, VFA concentration nor VFA molar proportions. Although this experimental design was not focused on the effect of 3-NOP dose on feedlot performance, no negative effects of any 3-NOP dose were detected on animal production parameters. Ultimately, the knowledge on the CH4 suppression pattern of 3-NOP may facilitate sustainable pathways for the feedlot industry to lower its carbon footprint. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of physically effective neutral detergent fiber (peNDF) and undigested neutral detergent fiber (uNDF) on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract nutrient digestibility for finishing cattle. Six Simmental heifers (668 ± 28.4 kg BW) were used in a replicated 3 × 3 Latin square (21 d periods) balanced for carry-over effects. Treatments included a control (CON ; Table 1) with no forage peNDF and minimal uNDF (peNDF: 0.0%, and uNDF: 4.88 ± 0.01; 95.15% barley grain, 4.51% vitamin and mineral supplement, and 0.34% urea on a DM basis). Pelleted wheat straw (PELL) was included at 10% of dietary DM by replacing barley grain to provide added uNDF but no forage peNDF (peNDF: 0.00%, and uNDF: 6.78 ± 0.02%). Finally, chopped wheat straw (STR) was included as a replacement for pelleted wheat straw to provide forage peNDF and uNDF (peNDF: 1.74 ± 0.06%, and uNDF: 6.86 ± 0.03%). Dry matter intake was not affected (P = 0.93) by treatments. Cattle fed CON spent less time ruminating (P = 0.010) and had less meals/d (P = 0.035) when compared with cattle fed STR, with those fed PELL being intermediate but not different from other treatments. Cattle fed CON had lesser ruminal pH (P = 0.020), and a greater duration that pH was < 5.5 (P = 0.020) as compared to cattle fed STR, with those fed PELL being intermediate but not different. Cattle fed CON and PELL had greater total short-chain fatty acid concentration (P = 0.003) and molar proportion of propionate (P < 0.001) when compared with cattle fed STR. Cattle fed STR had greater (P = 0.010) total ruminal pool size when compared with cattle fed CON and PELL. Cattle fed CON had greater (P = 0.043) duration between ruminal contractions when compared with cattle fed STR, with those fed PELL being intermediate. Cattle fed CON had greater serum amyloid A (P = 0.003) and haptoglobin (P < 0.001) concentration when compared with the other treatments. Cattle fed CON had greater dry matter (P < 0.001) digestibility when compared with the other treatments. In conclusion, inclusion of PELL and STR impacted eating behavior, but only STR affected ruminal fermentation, ruminal motility, systemic inflammation, and total tract nutrient digestibility in finishing cattle. These results are interpreted to suggest that the combination of peNDF and uNDF may be better than uNDF alone to adequately capture biological effects of NDF in high-concentrate diets. [ABSTRACT FROM AUTHOR]

Supplementation of ruminant diets with the methane (CH 4 ) inhibitor 3-nitrooxypropanol (3-NOP ; DSM Nutritional Products, Switzerland) is a promising greenhouse gas mitigation strategy. However, most studies have used high grain or mixed forage-concentrate diets. The objective of this study was to evaluate the effects of supplementing a high-forage diet (90% forage DM basis) with 3-NOP on dry matter (DM) intake, rumen fermentation and microbial community, salivary secretion, enteric gas emissions, and apparent total-tract nutrient digestibility. Eight ruminally cannulated beef heifers (average initial body weight (BW) ± SD, 515 ± 40.5 kg) were randomly allocated to two treatments in a crossover design with 49-d periods. Dietary treatments were: 1) control (no 3-NOP supplementation); and 2) 3-NOP (control + 150 mg 3-NOP/kg DM). After a 16-d diet adaption, DM intake was recorded daily. Rumen contents were collected on days 17 and 28 for volatile fatty acid (VFA) analysis, whereas ruminal pH was continuously monitored from days 20 to 28. Eating and resting saliva production were measured on days 20 and 31, respectively. Diet digestibility was measured on days 38–42 by the total collection of feces, while enteric gas emissions were measured in chambers on days 46–49. Data were analyzed using the mixed procedure of SAS. Dry matter intake and apparent total-tract digestibility of nutrients (DM, neutral and acid detergent fiber, starch, and crude protein) were similar between treatments (P  ≥ 0.15). No effect was observed on eating and resting saliva production. Relative abundance of the predominant bacterial taxa and rumen methanogen community was not affected by 3-NOP supplementation but rather by rumen digesta phase and sampling hour (P  ≤ 0.01). Total VFA concentration was lower (P  = 0.004) following 3-NOP supplementation. Furthermore, the reduction in acetate and increase in propionate molar proportions for 3-NOP lowered (P  < 0.001) the acetate to propionate ratio by 18.9% as compared with control (4.1). Mean pH was 0.21 units lower (P  < 0.001) for control than 3-NOP (6.43). Furthermore, CH4 emission (g/d) and yield (g/kg DMI) were 22.4 and 22.0% smaller (P  < 0.001), respectively, for 3-NOP relative to control. Overall, the results indicate that enteric CH4 emissions were decreased by more than 20% with 3-NOP supplementation of a forage diet without affecting DM intake, predominant rumen microbial community, and apparent total-tract nutrients digestibility. [ABSTRACT FROM AUTHOR]

Although in vitro data with mixed ruminal fluid demonstrated positive effects of posbiotic diet (POS) from lactobacilli on measures of fermentation and microbial profiles, there is a paucity of in vivo data with lactating ruminants. The aim of the study was to evaluate the effects of incorporating POS into diets of lactating goats on energy (E) partitioning, carbon (C) and nitrogen (N) balance, and performance. Ten late-lactation Murciano-Granadina goats were used in a crossover design with 26-d periods. Goats in the control diet (CON) were fed daily at the rate of 1 kg alfalfa hay and 1.5 kg concentrate, and the treatment group (POS) was fed CON with the addition of 3.75 g/d of Probisan Ruminants (PENTABIOL S.L. Navarra, Spain). No differences in DMI were detected. However, ruminal fluid propionate and apparent total tract digestibilities of NDF and ADF were greater (18%, 4.7%, and 5.2%, respectively; P  < 0.05) in POS compared with the CON diet. Daily partitioning of E to milk and efficiency of ME intake for milk production greater (11% and 3.0%, respectively; P  < 0.05) in POS compared with CON. The nonprotein RQ was greater in POS compared with CON due to greater (P  < 0.05) oxidation of carbohydrate (213 vs. 115 kJ/kg of BW0.75 per day) compared with fat (362 vs. 486 kJ/kg of BW0.75 per day). Although no differences were found in C balance, goats in POS had lower (P  < 0.05) amounts of C in CH4 (1.1 vs. 1.3 g/kg BW0.75 per day) compared with CON. There were no differences in N intake or N in feces or urine, but N in milk was greater (P  < 0.05) in POS compared with the CON diet (0.8 vs. 0.7 g/kg BW0.75 per day). Yield of fat-corrected milk (FCM) (3.20 vs. 2.72 kg/d; P  < 0.05) and concentration of true protein (3.4 vs. 3.3 kg/d; P  < 0.05) and lactose (4.7 vs. 4.5 kg/d; P  < 0.05) were greater in POS compared with CON. These responses were accompanied by lower (P  < 0.05) urea (12.3 vs. 16.6 mM/L) and ammonia-N (6.6 vs. 8.8 mg/L) without changes in fat concentration (6.1% vs. 6.0%; P  > 0.05) in POS compared with the CON diet. Daily amount of CH4 emission did not differ P  > 0.05 between diets. However, when expressed relative to unit of edible product, feeding POS reduced (P  < 0.05) the amount of CH4 by 46 g/kg of milk fat, 97 g/kg of milk protein, and 3 g/kg of milk compared with CON. Overall, data indicated that feeding a postbiotic in late-lactation increased energy efficiency for milk production partly by reducing CH4 emission. [ABSTRACT FROM AUTHOR]

To evaluate the effect of supplementing beef cattle with a ruminal probiotic consisting of native rumen microbes (NRM; Chordicoccus furentiruminis , Prevotella albensis , and Succinivibrio dextrinosolvens) on methane (CH4) emissions, growth performance, carcass characteristics, and plasma metabolites, Angus × SimAngus-crossbred steers (n = 32; 8 per pen) and heifers (n = 48; 12 per pen) with an initial body weight (BW) of 353 ± 64 kg were used in randomized complete block design. Cattle were blocked by sex and BW and randomly assigned to 1 of 2 treatments (2 pens per treatment). Treatments consisted of diets offered for ad libitum intake with (NRM) or without (CON) the inclusion of the ruminal probiotic. Cattle were fed a growing diet for 49 d followed by a ground corn-based diet for 124 ± 27 d until reaching the targeted final BW (635 kg for steers and 590 kg for heifers). Methane emissions were estimated using the GreenFeed system (n = 12 per treatment) prior to trial commencement (baseline; period 1), and on three (2, 3, and 4), and two (5 and 6) different sampling periods throughout the growing and finishing stage, respectively. All data were analyzed using the PROC MIXED procedure of SAS. For CH4 production (g/d), there was a tendency for an NRM supplementation × period interaction (P = 0.07) where cattle-fed diets with NRM had lower production of methane in periods 3 and 4. Including NRM in the diet decreased CH4 yield (g/kg of dry matter intake (DMI)) by 20%. For CH4 emission intensity (g/kg of average daily gain (ADG)), an interaction (P < 0.01) of NRM supplementation × period occurred. In periods 2 and 3, cattle-fed diets with NRM inclusion had lower CH4 emission intensity than CON cattle. During the 84-d period when all cattle were still on the finishing diet, feeding NRM increased (P = 0.02) ADG and tended to increase (P = 0.10) DMI. At the end of the 84-d period, cattle-fed NRM tended to be heavier (P = 0.06) than CON cattle. Cattle supplemented with NRM required less (P = 0.04) days on feed to reach the targeted final BW. No differences (P ≤ 0.11) were detected for gain-to-feed ratio and carcass characteristics. Cattle-fed NRM had greater abundance of uncultured rumen bacteria that may improve rumen digestion when fed a high grain diet and potentially promote the reduction of enteric CH4 production. Results from this study suggest that daily administration of NRM may be a strategy to mitigate methanogenesis and improve the growth performance of beef cattle. [ABSTRACT FROM AUTHOR]

The study aimed to assess the impact of three different non-forage fiber sources (NFFS); soy hulls (SH), cottonseed hulls (CSH), and beet pulp (BP) on methane (CH4) production and rumen fermentation using a 24-h batch culture system. These NFFS were incorporated partially into a conventional total mixed ration (TMR) diet consisting of alfalfa (40%), cracked corn (30%), soybean meal (10%), and an individual NFFS (20%; DM basis). Methane production, total gas production, volatile fatty acids (VFA) concentration, and dry matter (DM) digestibility were measured at the end of the incubation period. One way ANOVA test was used to analyze the means and significance was declared at P < 0.05. The results of the study indicated a significant 5% reduction (P < 0.05) in CH4 production with the BP diet compared with the other treatments. However, DM digestibility was found to be significantly less (P < 0.05) with the BP diet compared with the other diets. Total gas and VFA production were greater (P < 0.05) with the BP diet compared with the other diets. Additionally, the molar proportions of acetate and propionate were greater (P < 0.05) with the BP diet and least with the SH diet. No significant differences were recorded for the ratio of acetate to propionate (C2:C3) between treatment diets. Results from this study suggest that BP is a more effective non-forage fiber source in the TMR due to its favorable effects on rumen CH4 production and rumen fermentation. However, it is important to consider the trade-off with decreased DM digestibility when selecting BP as an NFFS in TMR diets. [ABSTRACT FROM AUTHOR]

The objective of this pilot study was to examine the impact of diet type on in vitro rumen fermentation characteristics using rumen fluid collected from grainfed and grass-fed American Bison (Bison bison). Rumen fluid was collected from 6 farmed American Bison at a commercial slaughter facility. At the time of slaughter, 3 grain-fed heifers (< 3 yr) were randomly selected for rumen fluid collection. On a separate day, 3 grass-fed cows (>3 yr) were randomly selected for rumen fluid collection. Rumen fluid was collected from each animal by obtaining rumen contents and filtering the rumen fluid from the digesta. For a given collection day, rumen fluid from the 3 animals was combined with McDougall’s buffering solution to generate rumen fluid buffer solution (RFB). The RFB was added to each pre-weighed digestion vessels (DV) containing no substrate (blanks) or 0.5 g of ground substrate (grain-based diet or forage- based diet). After filling, the DV were capped with one-way valves and incubated for 0, 12, 24, 48, and 72 h. At the end of each incubation period, DV were centrifuged, and supernatant was removed and analyzed for VFA concentrations. The remaining pellet was dried at 60°C for 24 h to determine dry matter digestibility (DMD). Descriptive statistics were used to describe DMD characteristics for rumen fluid collected from bison from each production system. Linear, quadratic, and cubic responses were analyzed for DMD. Linear, quadratic, and cubic contrasts were used to examine DMD over time. In vitro DMD increased quadratically (P < 0.05) for grain-fed bison and linearly (P < 0.05) for grass-fed bison over time. Final 72 h DMD was 84.5% ± 0.05 and 70.0% ± 0.11 for grain-fed and grass-fed bison, respectively. Final molar proportions of acetate, propionate, isobutyrate, and butyrate were 55.3% ± 0.01, 25.8% ± 0.002, 1.9% ± 0.01, and 17.0% ± 0.001 for grain-fed bison and 31.0% ± 0.02, 41.2 ± 0.02, 3.9% ± 0.01, and 23.2% ± 0.01 for grass-fed bison. Molar proportions of all VFA exhibited a cubic response (P < 0.05) over time for rumen fluid collected from both grain-fed and grass- fed bison. These data provide a preliminary insight into in vitro rumen fermentation characteristics of bison from different production systems. [ABSTRACT FROM AUTHOR]

Globally cattle convert low-quality forage to beef and milk; therefore, understanding protein utilization in Bos taurus taurus is critical to enhancing sustainability as over and under-supplementation of protein are economically and environmentally costly. Lowquality forage lacks the N necessary for proper utilization and metabolic function. Supplemental protein improves low-quality forage utilization and is expected to increase N absorption and retention. Supplement starch can increase volatile fatty acid (VFA) production and energy supplied to the animal; however, too much starch decreases ruminally available N and pH potentially decreasing fibrolytic activity. Accordingly, our objective was to determine the effect starch supplementation on N balance and ruminal fermentation parameters in Bos taurus steers. Ruminally cannulated Angus steers [n = 5; body weight (BW) = 375 ± 45 kg] were used in a 4 × 4 Latin square to evaluate the effect of decreasing supplemental starch when consuming King Ranch Bluestem hay (3.5% CP, 73% NDF). Steers received four isonitrogenous (130 mg N/kg BW) supplements providing increasing levels of starch (2% starch = 100% soybean meal; 20% starch = 26.3% corn, 73% soybean meal, 0.7% urea; 38% starch = 51.6% corn, 47% soybean meal, 1.4% urea; 56% starch = 78.6% corn, 19% soybean meal, 2.4% urea). Five 14-d periods were conducted, consisting of 9 d adaptation and 4 d to measure intake and digestion, and 1 d for ruminal fermentation. Supplemental N intake decreased linearly (P < 0.01) with increasing starch as the crude protein content of the soybean was underestimated. Forage and total N intake were not affected by starch level (P ≥ 0.17). Fecal and total urinary N excretion were not different between starch levels (P ≥ 0.43). Urinary ammonia-N and urea-N averaged 6.6 and 16.8% of total urinary N excretion, respectively, but no differences between starch levels were observed (P ≥ 0.39). Level of starch supplementation had no effect on N retention and absorption (P ≥ 0.50). There was a treatment × time interaction observed for ruminal ammonia concentration (P < 0.01). All treatments, except 2% starch, peaked at 4 h post feeding, 20 and 38% treatments gradually decreased following four, but the concentration of ruminal ammonia decreased by 80% between 4 h and 8 h after feeding in the 56% starch treatment. Starch level had no effect total VFA concentration, VFA molar proportions, or ruminal pH (P ≥ 0.10). In conclusion, providing supplemental starch did not affect N balance or VFA production when fed to steers consuming low-quality forage. Nitrogen balance and VFA production likely were not affected because all supplements provided sufficient ruminally available N and, therefore, exerted minimal effects on forage utilization. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate whether post-ruminal provision of a yeast cell wall extract (YCW) affected gastrointestinal fermentation characteristics and permeability, and white blood cell concentrations for heifers exposed to feed restriction (FR). Ruminally cannulated beef heifers (n = 8) were used in a 2 × 2 crossover design. Treatments (TRT) included an abomasal infusion of a placebo (PLC; maltodextrin) or YCW derived from Saccharomyces cerevisiae (2 g/dose) infused at 0600 and 1800 h. Heifers were subject to a 5-d baseline period followed by 5 d of FR where dry matter intake (DMI) was restricted to 30% of ad libitum intake. Data collection included daily DMI, and rumen, fecal and blood samples. Total gastrointestinal and post-ruminal permeability were measured using a ruminal dose of Cr-EDTA and an abomasal dose of Co-EDTA during the baseline and FR phases. Data were analyzed to determine the effects of YCW provision and phase, and the 2-way interaction. There were no TRT or TRT × phase interactions except for fecal propionate concentration. By design, DMI during FR was 30% (P < 0.01) of that observed during baseline (4.1 vs. 13.4 kg/d, respectively). The ruminal concentrations of acetate (45.4 vs. 69.2 mmol/L), propionate (14.5 vs. 26.7 mmol/L), and butyrate (9.9 vs. 16.5 mmol/L) were reduced (P < 0.01) by 34, 46, and 52%, respectively, with FR relative to baseline. Fecal propionate concentration (interaction, P = 0.04) numerically increased (P = 0.12) from baseline to FR for PLC (7.7 vs. 9.6 mmol/L, respectively), while YCW did not change among phases; however, no means differed. Exposure to FR reduced fecal butyrate concentration by 28% (P = 0.03). Gastrointestinal tract permeability (P < 0.01; 2.3 and 2.5% for total and postruminal, respectively) was greater during FR compared with baseline, with 2.0% of the Cr-EDTA and 1.6% of the Co-EDTA excreted in urine. The concentrations of neutrophils (P = 0.03) and eosinophils (P < 0.01) were greater during FR relative to baseline (2.28, 1.27 and 0.53, 0.30 ×106 cells/mL, respectively). Exposure to FR altered ruminal SCFA concentrations, increased blood concentrations of neutrophils and eosinophils, and increased gastrointestinal permeability suggesting an inflammatory response; however, post-ruminal provision of a YCW did not mitigate the response to a feed restriction challenge. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the influence of a Bacillus-based probiotic supplementation on intake, digestibility, and ruminal fermentation parameters of beef cows consuming a low-quality forage diet (7.0% CP, 60% NDF, 39% ADF, DM basis). Ruminally fistulated Angus × Hereford cows [n = 15; age = 6.1 ± 1 yr; body weight (BW) = 655 ± 57] were used in two identical complete randomized designs, housed in individual pens with water, and forage intake monitored daily. Treatments consisted of 1) 500 g of protein supplement (dry distillers grain + mineral mix) without probiotic (CON n = 15), and 2) 500 g of protein supplement + 3 g of a probiotic containing Bacillus licheniformis and B. subtilis (BOV; n = 15; 2.2 ×109 CFU of the mixture/g; Bovacillus, Novonesis, Hørsholm, Denmark). Each experimental period lasted 33 d, consisting of 21 d of adaptation, 12 d of collection, and 30 d of wash-out between periods. From d 22 to 26, fecal samples were collected to determine intake and nutrient digestibility using titanium dioxide as an indigestible marker. On d 27, ruminal fluid was collected at h 0 (before feeding), 4, 8, 12, 16, and 20 postfeeding to evaluate short-chain fatty acid (SCFA) and N-NH3 concentration. From d 28 to 32, hay samples (4 g) were fitted in Dracon bags and incubated in the rumen for 0, 12, 24, 48, 72, 96, and 120 h to determine nutrient digestibility. Cows receiving BOV had greater (P < 0.001) dry matter intake compared with the CON group (Table 1). Also, cows supplemented with BOV had greater (P < 0.02) dry matter and protein digestibility and a tendency (P ≤ 0.07) for greater NDF and ADF forage digestibility compared with CON. A tendency was also detected (P = 0.09) for the degradability of forage dry matter, which was improved in BOV vs. CON. No effects were observed on rumen fermentation characteristics (P ≥ 0.14; Table 2).). In conclusion, adding bacillus-based probiotics enhanced the intake, nutritional digestibility, and degradability of beef cows fed medium-quality forage diets. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of extruded rapeseed straw (ERS) as a replacement for peanut vine (PV) on nutrient intake, rumen fermentation, and growth performance of Hu sheep of China. Male Hu sheep [n = 36; body weight (BW) = 19.5 ± 1.0 kg] were randomly assigned to one of three experimental diets: 1) 0% ERS (Control): 100% PV, no ERS; 2) 50% ERS: 50% ERS+50% PV; or 3) 100% ERS: 100% ERS, no PV. The preliminary trial period was 10 d, and the formal trial period was 90 d. Feed intake was recorded once daily, and weighing was conducted every 30 d. Over all periods, substituting of PV with ERS had no effect on intake of starter feed, metabolizable energy (ME), digestible energy (DE), but had greater total intake energy (GE; P < 0.05). Also, 50% ERS had greater fecal energy but decreased urinary energy compared with control group. Compared with the control, 100% ERS resulted heavier BW and average BW gain per day (ADG) during d 61 to 90 of the experiment (P < 0.05), together with greater feed efficiency (P < 0.05). Compared with control, the rumen concentration of NH3-N increased for 50% ERS and the rumen pH was higher (P < 0.05). When compared with PV, total volatile fatty acids concentrations, propionate and valerate concentrations, and the molar proportions of ruminal acetate were less in ERS groups (P < 0.05), while the concentrations of acetate, isobutyric, isovaleric acid and acetate propionate were greater when substituting of PV with ERS in 50% and 100% (P < 0.05). Concentration of butyrate was not different among treatments. Body measurements were not affected by the treatments. In conclusion, substitution of PV with ERS may improve nitrogen utilization efficiency and rumen fermentation in Hu sheep, also slightly improve growth performance during later fattening period without negative affect on energy intake. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the factors which influence intake and fiber digestion efficiency of beef cattle previously selected for high or low digestible neutral detergent fiber (NDF) intake (DFI; g/kg BW0.75). Angus × Hereford cross heifers [n = 16; initial body weight (BW) = 584 ± 32.2 kg] previously classified as either high or low DFI when fed a high-forage diet (n = 8/treatment) were individually housed and fed one of 4 diets for ad libitum intake using a sequential offering of diets over four consecutive 28-d period. Diets included: 1) 100% grass hay; 2) 100% mature alfalfa hay; 3) 90% dry rolled barley + 10% alfalfa hay; and 4) 90% dry rolled barley + 10% grass hay (DM basis). Individual animal feed intake was recorded daily in addition to weekly BW. Rumen digesta samples were collected prior to feeding and 6 h after for 2 d within each period and analyzed for SCFA and NH3 -N concentrations, and total rumen protozoa counts and identification. High DFI heifers had similar (P > 0.11) DMI compared with low DFI heifers in periods 1, 3, and 4, but had a tendency for greater DMI in period 2 and NDF intake during period 2 and 3 (7.84 vs. 7.07 kg, P = 0.07; 4.71 vs. 4.27 kg, P = 0.08; 2.56 vs. 2.28 kg, P = 0.10). ADG was greater for high DFI during the first two periods (0.61 vs. 0.13, P = 0.04; 0.44 vs. -0.09, P = 0.02); moreover, high DFI cattle finished the study with a heavier BW (708 vs. 661 kg, P = 0.04). Total SCFA concentrations before and 6 h after feeding did not differ (P ≥ 0.36) between treatments. NH3 -N concentrations were not different before feeding during period 1, 3, and 4, but were greater for high DFI heifers during period 2 (9.85 vs. 8.39, P = 0.04). Additionally, there were no differences in NH3 -N concentrations 6 h after feeding during any period. No differences were observed (P > 0.25) between treatment groups for total rumen protozoa counts for periods 1 and 2; however, there was a tendency for a greater proportion of Isotrichia before feeding during period 1 (3.67 vs. 2.41%, P = 0.07). In conclusion, differences in intake and the small changes in ruminal fermentation parameters only partially explain the differences in ADG observed between high and low DFI heifers. [ABSTRACT FROM AUTHOR]

Boar taint is an off-putting odor found in the meat of entire male pigs due to the accumulation of androstenone and skatole in the fat. Development of boar taint is dependent on the balance between the rate of synthesis and metabolism of these compounds. Prior studies have shown that feed ingredients high in fermentable carbohydrates, including chicory root, sugar beet pulp, and Jerusalem artichoke decreased the synthesis of skatole in the hindgut and altered the metabolism in the liver, resulting in a skatole concentrations comparable with castrated males. However, the mechanism of how these dietary fermentable carbohydrates affect liver metabolism is not well understood. Metabolism of boar taint compounds takes place in a two-phase process, regulated by various enzymes and cytochrome families. Short-chain fatty acids (SCFAs) are produced from the microbial fermentation of fiber and have been shown to have regulatory effects on histone deacetylases and gene expression in humans, providing a potential mechanism in which feed high in dietary fiber reduces boar taint. The purpose of this study was to assess if SCFA directly affect the metabolism of androstenone in liver hepatocytes. Primary hepatocytes were isolated from the liver of 6 [(Yorkshire x Landrace) x Duroc] boars weighing around 90 kg. Cells were treated in triplicate with acetate, butyrate, propionate, and various combinations for 24 h to alter gene expression. Two sets of wells acted as a control, not being treated with SCFAs. The cells were then incubated with androstenone for 3 h, and media was extracted, and metabolite production was analyzed using high-performance liquid chromatography. The effects of treatments were using a one-way ANOVA with a Dunnet’s adjustment for multiple comparisons to a control. Results showed the combined acetate, butyrate, and propionate treatment had the greatest effect on androstenone glucuronide production when compared with the control, resulting in significant increases (P < 0.05) ranging from 82 ± 1.6% to 1 ± 2.4% in individual boars. Other treatments had a similar effect, significantly increasing the production of androstenone glucuronide but to a lesser degree. Butyrate increased production ranging from 40 ± 2.2% to 5±1.5% (P < 0.05), propionate from 38 ± 3.6% to 3 ± 2.6% (P < 0.05), acetate and butyrate from 61±3.9% to 1 ± 2.8% (P < 0.05), acetate and propionate from 70±3.5% to 5±1.7% (P < 0.05), and butyrate and propionate from 82 ± 2.5% to 4 ± 1.1% (P < 0.05) when compared with the control. In conclusion, this trial provided evidence that SCFAs produced by the microbial fermentation of fiber can significantly increase hepatic androstenone metabolism in some animals, with a wide range in these effects among individual boars. Future research will involve assessing the effects of SCFAs on hepatic skatole metabolism [ABSTRACT FROM AUTHOR]

Metronidazole is a potent antibiotic often prescribed to treat gastrointestinal enteropathies, but is known to induce loose stools, negatively alter the fecal microbiome, and affect fecal metabolite production. Dietary intervention may aid in post-antibiotic recovery, but little research has been conducted regarding the potential of fiber utilization for microbial recovery in canines. Using an in vitro fermentation assay, the objective was to investigate the fermentation characteristics of dietary fibers using fecal inocula from dogs treated with metronidazole. All procedures were approved by the University of Illinois IACUC prior to experimentation. Healthy male beagles (n = 4) were fed a commercial canned diet for 2 wk, then administered metronidazole [20 mg/kg body weight (BW) twice a day] for 2 wk. Fresh fecal samples were collected at wk 2 [diet only (CTL)] and 4 [antibiotic treatment (ANT)], stabilized in a 20% glycerol solution, and then frozen. On the in vitro fermentation day, feces from each time point were thawed and used to inoculate tubes. At baseline and after 6, 12, and 18 h of fermentation, pH, short-chain fatty acid (SCFA) concentrations, and microbiota populations were measured. SCFA were measured by gas chromatography and fecal microbiota populations were analyzed by 16S rRNA sequencing. All blank tube-corrected changes from baseline data were analyzed using repeated measures and the MIXED procedure of SAS 9.4, with significance set at P < 0.05. QIIME2 analysis was used for bacterial diversity measures. As expected, metronidazole administration heavily influenced microbiota populations and fiber fermentability characteristics. Pectin fermentation reduced (P < 0.001) pH and increased (P < 0.001) SCFA concentrations over time, but responses were less (P < 0.001) in ANT tubes than CTL tubes. Beet pulp fermentation also reduced (P < 0.001) pH and increased (P < 0.001) SCFA concentrations over time. Whereas the magnitude of pH change was small between inoculum sources, SCFA concentrations were different (P < 0.001) between ANT tubes and CTL tubes. Propionate and butyrate concentrations were greater (P < 0.001) in CTL tubes than ANT tubes at all time points, but acetate concentrations varied over time. Chicory pulp fermentation reduced (P < 0.001) pH over time, with greater (P < 0.01) reductions in ANT tubes than CTL tubes. Chicory pulp fermentation increased SCFA concentrations, but had different patterns based on inoculum source. Metronidazole altered microbiota populations by reducing (P < 0.001) bacterial alpha diversity. The analysis of bacterial beta diversity revealed separate clusters for dogs in the absence and presence of metronidazole. Beta diversity analysis also showed that tubes containing chicory pulp clustered separately from those containing the other fibers. Relative abundances of over 50 bacterial genera differed (P < 0.05) among inoculum sources. In summary, interesting fermentation patterns in response to varying fiber sources were observed, allowing for improved insight into their potential abilities when provided to antibiotic-treated dogs. [ABSTRACT FROM AUTHOR]

The rumen simulation technique (RUSITEC) was used to investigate the effect of ergot alkaloids (EA) and a mycotoxin deactivating product (Biomin AA; MDP) on nutrient digestion, ruminal fermentation parameters, total gas, methane, and microbial nitrogen production. Ruminal fermentation vessels received a feedlot finishing diet of 90:10 concentrate:barley silage (DM basis). Using a randomized complete block design, treatments were assigned (n = 4 vessels/treatment) within two RUSITEC apparatuses in a 2 × 2 factorial arrangement. Treatments included: (1) control (CON) diet (no EA and no MDP); (2) CON diet + 1 g/d MDP; (3) CON diet + 20 mg/kg EA; and (4) CON diet + 20 mg/kg EA + 1 g/d MDP. The study was conducted over 14 d with 7 d of adaptation and 7 d of sample collection. Data were analyzed in SAS using PROC MIXED including fixed effects of EA, MDP, and the EA×MDP interaction. Random effects included RUSITEC apparatus and cow rumen inoculum (n = 4). Ergot alkaloids decreased dry matter (DMD) (P = 0.01; 87.9 vs. 87.2%) and organic matter disappearance (OMD) (P = 0.02; 88.8 vs. 88.4%). Inclusion of MDP increased OMD (P = 0.01; 88.3 vs. 88.9%). Neutral detergent fiber disappearance (NDFD) was improved with MDP; however, an EA×MDP interaction was observed with MDP increasing (P < 0.001) NDFD more with EA diet compared to CON. Acetate proportion decreased (P = 0.01) and isovalerate increased (P = 0.03) with EA. Consequently, acetate:propionate was reduced (P = 0.03) with EA. Inclusion of MDP increased total volatile fatty acid (VFA) production (P < 0.001), and proportions of acetate (P = 0.03) and propionate (P = 0.03), and decreased valerate (P < 0.001), isovalerate (P = 0.04), and caproate (P = 0.002). Treatments did not affect (P ≥ 0.17) ammonia, total gas, or methane production (mg/d or mg/g of organic matter fermented). The inclusion of MDP reduced (P < 0.001) microbial nitrogen (MN) production in the effluent and increased (P = 0.01) feed particle-bound MN. Consequently, total MN decreased (P = 0.001) with MDP. In all treatments, the dominant microbial phyla were Firmicutes, Bacteroidota, and Proteobacteria, and the major microbial genus was Prevotella. Inclusion of MDP further increased the abundance of Bacteroidota (P = 0.04) as it increased both Prevotella (P = 0.04) and Prevotellaceae_UCG-003 (P = 0.001). In conclusion, EA reduced OMD and acetate production due to impaired rumen function, these responses were successfully reversed by the addition of MDP. [ABSTRACT FROM AUTHOR]

Plant secondary metabolites (PSM) such as condensed tannins, hydrolysable tannins, saponins and essential oils purportedly impact rumen fermentation at low inclusion rates in beef cattle diets. Twelve steers (347 ± 23 kg BW) of British and continental influence were allocated to 1 of 4 replicated 3 x 3 Latin squares. Latin squares each had 14 d periods (10 d adaptation and 4 d for sample collection). All cattle were fed ground warm-season hay (89.5% DM, 92.8% OM, 65.9% NDF, 43.6% ADF, 6.70% CP) at 1.5% of BW (DM-basis) and supplemented with soybean meal at 0.18% of BW (DM-basis) once daily. Treatments consisted of a blend of tannins, saponins and essential oils provided at 0% (Control), 0.1% (Low) and 0.3% (High) of hay offering. Treatments were mixed with daily soybean meal allotment and provided before feeding of hay. Urine and feces were completely collected from d 11 through 14 at 0730 h and daily amounts of urine and feces produced were measured gravimetrically. Measures of gaseous exchange were determined via indirect calorimetry on d 13 and 14. Open-circuit respiration calorimeters (91.4 x 91.4 x 191.2 cm) were used to collect respired gas and ruminal methane production. Total oxygen consumption and production of carbon dioxide and methane were calculated from the difference in concentration of oxygen, carbon dioxide, and methane from air exhausted from each calorimeter and concentration of oxygen, carbon dioxide, and methane in ambient air and multiplied by amounts of air flowing from each calorimeter standardized for temperature, pressure, and humidity. Data were analyzed for a Latin square using the MIXED procedure of SAS with fixed effect of treatment, period and square and random effect of steer. Linear and quadratic contrast coefficients were assigned using PROC IML for uneven spacing of treatments. Significance was declared when P ≤ 0.05. Per experimental design, forage N and OM intake did not differ (P ≥ 0.77). Apparent total tract digestion of OM, NDF and ADF did not differ (P ≥ 0.66) among treatments. Fecal nitrogen excretion, and the percentage of N excreted in feces increased linearly (P = 0.01). N balance tended (P = 0.08) to decrease linearly with increasing PSM supplemented. Methane (L/kg DMI) was not affected (P = 0.28) by treatments. Methane, GE, DE, and ME (mcal/kg DMI) was unaffected (P = 0.19) by treatment. Under the conditions of this experiment, a blend of PSM had little effect on rumen fermentation or energy metabolism in beef steers. [ABSTRACT FROM AUTHOR]

With increased use of automated feeders, like the bait dispenser on an automated head chamber system (AHCS; GreenFeed; C-Lock Inc., Rapid City, SD), more scientists are investigating ways to use this equipment. Scientist with the Agricultural Research Service initially conducted an experiment to determine if dosing titanium dioxide (TiO2) through an AHCS is an alternative to the traditional hand-fed dosing method for estimating fecal output (FO). The AHCS used had a 2-hopper bait dispensing system, where one hopper contained alfalfa pellets marked with 1% TiO2 and the other contained alfalfa pellets. During the morning (0800), hand-fed heifers received 32 g of TiO2-marked pellets, whereas AHCS-dosed heifers also received 32 g of marked pellets during their first visit each day. A two one-sided t-test indicated the FO estimates were similar (P = 0.04), but the AHCS dosed heifers had greater (P < 0.01) variability; this difference in FO variability is probably due to the increased variability in dosing time (0615 ± 6.2 h). This research has highlighted the potential for dosing cattle with a marker through the AHCS, but conventional fecal marker methods assume steady-state concentration. Our research has shown that errors associated with external marker methods are not highly associated with analytical techniques but are most influenced by dose size and sampling inaccuracy. Hence, ad libitum use of an AHCS results in non-steady-state fecal concentrations. To determine whether reliable FO estimates could be obtained under conditions of irregular but known dose times, we designed 2 experiments where the steady-state assumptions were relaxed, and fit known time measured fecal concentrations to multi-dose digesta kinetics models to estimate FO. In these experiments we used individually penned, rumen fistulated Dexter steers and limit-fed a diet of hay and protein supplement. First, after a 7-d dietary acclimation, steers were given a dose of TiO2 through the rumen fistula and again on d 14, and over 120 h after each dose, 14 spaced fecal samples were collected. In Exp. 2, steers received the first of 6 daily doses, then on d 7 no dose, and on days 8 to 12 daily dosing resumed. Beginning on d 7, when dosing was skipped, fecal sampling began and over a 120-h period 14 fecal samples were collected. For Exp. 1, marker concentration data were fit to a G2 digesta kinetics model and for Exp. 2, concentration data were fit to a multi-dose G2 digesta kinetics model assuming identical digesta kinetics for each dose and the concentration over time as the sum of each pulse. Measured FO in Exp. 2 was 11% greater than the estimates obtained from fitting measured concentrations to multi-dose digesta kinetics models. [ABSTRACT FROM AUTHOR]

The objective of the experiment was to evaluate a commercial Saccharomyces cerevisiae fermentation product (SCFP; NaturSafe, Dimond V, Cedar Rapids, IA) on performance, plasma metabolites, rumen parameters, and fecal pathogen shedding in feedlot steers. Crossbred steers (n = 61; 271 ± 48.1 kg) were sourced from 3 different research units at Oklahoma State University and assigned to 1 of 3 experimental treatments in a randomized complete block design. Steers were group housed in pens equipped with an automated individual feed intake system. Treatments consisted of a negative control (CON), CON with tylosin phosphate (TYL; 9.9 mg ⋅ kg-1 of diet DM), or CON with SCFP (1.63 g ⋅ kg-1 of diet DM). Body weight and feed efficiency did not differ among treatments (P ≥ 0.12). However, steers fed SCFP tended to have greater ADG from d 35 to 56 (P = 0.10). In addition, steers fed SCFP exhibited increased DMI from d 56 to 112 (P = 0.03), a tendency for increased DMI from d 112 to final (P = 0.07), and increased DMI overall (P = 0.05). There was no treatment x time interaction for pH, pH change, or lactate concentrations in rumen fluid (P ≥ 0.11), but all were impacted by time (P < 0.01). A treatment x time interaction (P < 0.01) was detected for fecal pH and fecal pH change, with the pH being greater in TYL fed steers on d 56 and in CON fed steers on the final day. Steers that consumed CON had a reduced fecal pH (P < 0.01) and steers consuming SCFP tended to have a reduced fecal pH (P = 0.08) from d 35 to 56 compared with TYL fed steers, while both CON and SCFP fed steers experienced an increase in fecal pH from d 56 to 112 (P < 0.01). A time effect was detected (P ≤ 0.04) for plasma glucose, lactate, urea nitrogen, and non-esterified fatty acid concentrations among treatment groups. A treatment x time interaction was observed (P < 0.02) for stx2 genes of Shiga toxin producing Escherichia coli (STEC) in individual fecal samples where SCFP and TYL fed steers tended to exhibit an increased concentration compared with CON fed steers on d 14, while on d 190 CON and SCFP fed steers exhibited an increased concentration compared with TYL fed steers. Overall, STEC, E. coli O157:H7, and Salmonella concentrations were all impacted by time (P < 0.001). This experiment suggests that SCFP could be utilized as a potential alternative to TYL in feedlot cattle without adversely affecting cattle performance. However, SCFP did not impact pathogen shedding. In addition, CON fed steers performed similarly to both SCFP and TYL fed steers. [ABSTRACT FROM AUTHOR]

Gluconate salts have been identified as a butyrate precursor when fed to non-ruminant species and may increase the butyrate concentration in the large intestine supporting gastrointestinal health and development. The objective of this study was to evaluate the dose response of hydrogenated fat-embedded calcium gluconate (HFCG) on performance and gastrointestinal tract (GIT) development in growing lambs. Thirty-two wether lambs were used in a randomized complete block design and assigned to 1 of 4 treatments differing in the inclusion of HFCG: 0.0% (CON), 0.075% (LOW), 0.30% (MED), and 0.60% of the diet (HIGH). Lambs were allocated into individual pens and fed ad libitum with feed delivered twice daily. Feed intake was recorded daily, and body weight (BW) was assessed at the beginning and the end of the 29-d period. Blood was sampled on day 21, prior to feeding and 6 h post-feeding to evaluate changes in β-hydroxybutyrate, glucose, and insulin concentrations. Total fecal collection was conducted during days 25 to 28 to assess apparent total tract digestibility. On day 29, lambs were slaughtered, and the entire GIT was separated by region to enable sampling of tissue and digesta. Data were analyzed to assess linear, quadratic, and cubic effects of HFCG dose. Final BW, average daily gain, and dry matter intake decreased linearly (P ≤ 0.02) with increasing HFCG. Increasing inclusion of HFCG linearly decreased (P = 0.01) the thickness of the stratum corneum in ruminal papillae but did not affect other strata (P ≥ 0.34). Omasal digesta weight linearly decreased (P = 0.01) as the concentration of HFCG increased and abomasal digesta weight was cubically affected (P = 0.03) the increasing dose of HFCG. Short-chain fatty acid concentration in the cecum was cubically affected (P < 0.01) with increasing dose of HFCG where low dose had the greatest concentration. Moreover, increasing the dietary supply of HFCG linearly increased the proportion of acetate (P = 0.04) in the cecum and linearly decreased the proportion of propionate in the digesta of both the cecum (P < 0.01) and colon (P = 0.01). Colon crypt depth was quadratically (P = 0.03) affected with the increasing dose of HFCG, where lambs fed MED had greatest crypt depth. We conclude that feeding HFCG to growing lambs did not increase butyrate concentration in the large intestine and consequently does not increase the absorptive surface area of the whole tract, the size of the GIT, or the functionality of the intestine. [ABSTRACT FROM AUTHOR]

Condensed tannins (CT), one of the most ubiquitous compounds in the plant kingdom, can modulate ruminal nutrient metabolism. Objectives were to study potential interactions of CT and polyunsaturated fatty acids (PUFA) on ruminal fermentation, biohydrogenation (BH), and methane production. Ruminal fluid obtained from lactating Holstein Friesian cows was used. All experiments were carried out as a completely randomized design with the same mixed diet: control (60:40 forage:concentrate) without supplement (CON), 2.5% soybean oil (SBO), and SBO + grape seed tannin extract (GSTE) at 0.2%, 0.4%, 0.6%, or 0.8% dietary DM (ST0.2, ST0.4, ST0.6, and ST0.8, respectively). Compared with CON (84.7 mM), total VFA concentration was not affected by SBO, but decreased (P < 0.001) with ST0.8 vs. ST0.6 (75.3 vs. 78.3 mM). Relative to CON, methane production was depressed (P < 0.001) by 17.7% and 28.0% in ST0.4 and ST0.8. The highest (P < 0.001) mean concentrations of c 9, t 11 CLA and C18:1 t 11 were observed with ST0.4 compared with CON, but there was no difference between SBO and CT-containing diets. Disappearance of C18:2 c 9, c 12 was 49.1% vs. 50.3% in CON vs. SBO, whereas it ranged from 39.9% to 46.3% in CT-containing diets after 2 h incubation (P < 0.001). Concentrations of c 9, t 11 CLA with supplemental SBO and ST0.8 nearly peaked (P < 0.001) at 2 h incubation, but this fatty acid peaked (P > 0.05) at 6 h incubation and remained higher (P < 0.001; 15.9–17.0 µg/mL) at 24 h incubation with ST0.2, ST0.4, and ST0.6 compared with other diets (13.5–14.5 µg/mL). Compared with CON (50.6 µg/mL), concentration of C18:1 t 11 with SBO and CT-containing diets reached a peak (P < 0.001; 241–265 µg/mL) at 12 h incubation. Concentration of C18:0 was 171%–231% higher (P < 0.001) with SBO and CT relative to CON at 24 h incubation. Overall, these results demonstrated that PUFA in SBO are more effective in modulating ruminal BH and CH4 production when combined with CT. However, high doses of added CT can reduce ruminal VFA concentration. Thus, a level of 0.4% GSTE added to diets containing 2.5% PUFA from plant origin might be suitable for optimizing ruminal fermentation and BH of C18:2 c 9, c 12 to fatty acid intermediates that could have beneficial effects to human health. [ABSTRACT FROM AUTHOR]

Six ruminally cannulated steers (average BW = 791 ± 71 kg) were used in a replicated 3 × 3 Latin square experiment to determine the effects of roughage type on rumination, fiber mat characteristics, and rumen fermentation variables. Three roughages were included at 7% (DM basis) in a steam flaked corn-based diet: cotton burrs (CB), wheat silage (WS), or corn stalks (CS). Steers were fitted with a sensory collar to record rumination behaviors in 2-h intervals at the beginning of the experiment. Each 30-d period consisted of 7 d of recovery, 14 d of diet adaptation, 7 d of rumination data collection (daily and bi-hourly average rumination), 1 d of rumen fluid collection, and 1 d of rumen evacuations. In situ degradation of individual roughages was determined for 4 d after period 3 evacuations. During rumen evacuations, ruminal contents were removed; the rumen fiber mat (RF) was separated from the liquid portion with a 2-mm sieve, weighed, and a subsample was dried. Data were analyzed using the MIXED procedure of SAS with steer as the experimental unit and roughage (CB, WS, and CS) as the main effect. Dry matter intake (DMI) was not different for CB and WS (P = 0.25) and greatest for steers consuming CS diet (P ≤ 0.01). Roughage type did not influence the weight of the RF dry matter (%; DM; P = 0.92), RF weight (P = 0.69), or RF:DMI ratio (P = 0.29). Daily rumination (min/d) did not differ among roughages (P = 0.40), but min of rumination/kg of DMI was greatest for CS (18.0 min), min/kg of NDF was greatest for WS (89.8 min; P = 0.02), and min/kg of peNDF was greatest for CS (132.4 min; P ≤ 0.01). Wheat silage had the greatest percentage of soluble and degradable DM. Rumen fiber mat did not differ for roughages, although rumination min/kg of DMI and peNDF was greatest for steers consuming CS and WS. In situ degradation determined that CB-R and CS-R had the greatest percentage of ruminal undegraded DM. Based on the objective of the experiment, roughage type did not influence daily rumination or fiber mat characteristics. [ABSTRACT FROM AUTHOR]

In theory, supplementing xylanase in corn-based swine diets should improve nutrient and energy digestibility and fiber fermentability, but its efficacy is inconsistent. The experimental objective was to investigate the impact of xylanase on energy and nutrient digestibility, digesta viscosity, and fermentation when pigs are fed a diet high in insoluble fiber (>20% neutral detergent fiber; NDF) and given a 46-d dietary adaptation period. A total of 3 replicates of 20 growing gilts were blocked by initial body weight, individually housed, and assigned to 1 of 4 dietary treatments: a low-fiber control (LF) with 7.5% NDF, a 30% corn bran high-fiber control (HF; 21.9% NDF), HF + 100 mg xylanase/kg (HF + XY [Econase XT 25P; AB Vista, Marlborough, UK]) providing 16,000 birch xylan units/kg; and HF + 50 mg arabinoxylan-oligosaccharide (AXOS) product/kg (HF + AX [XOS 35A; Shandong Longlive Biotechnology, Shandong, China]) providing AXOS with 3–7 degrees of polymerization. Gilts were allowed ad libitum access to fed for 36-d. On d 36, pigs were housed in metabolism crates for a 10-d period, limit fed, and feces were collected. On d 46, pigs were euthanized and ileal, cecal, and colonic digesta were collected. Data were analyzed as a linear mixed model with block and replication as random effects, and treatment as a fixed effect. Compared with LF, HF reduced the apparent ileal digestibility (AID), apparent cecal digestibility (ACED), apparent colonic digestibility (ACOD), and apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), crude protein (CP), acid detergent fiber (ADF), NDF, and hemicellulose (P < 0.01). Relative to HF, HF + XY improved the AID of GE, CP, and NDF (P < 0.05), and improved the ACED, ACOD, and ATTD of DM, GE, CP, NDF, ADF, and hemicellulose (P < 0.05). Among treatments, pigs fed HF had increased hindgut DM disappearance (P = 0.031). Relative to HF, HF + XY improved cecal disappearance of DM (162 vs. 98 g; P = 0.008) and NDF (44 vs. 13 g; P < 0.01). Pigs fed xylanase had a greater proportion of acetate in cecal digesta and butyrate in colonic digesta among treatments (P < 0.05). Compared with LF, HF increased ileal, cecal, and colonic viscosity, but HF + XY decreased ileal viscosity compared with HF (P < 0.001). In conclusion, increased insoluble corn-based fiber decreases digestibility, reduces cecal fermentation, and increases digesta viscosity, but supplementing xylanase partially mitigated that effect. [ABSTRACT FROM AUTHOR]

Providing supplements that enhance the efficiency of feed utilization can reduce methane (CH4) emissions from ruminants. Protein supplementation is widely used to increase intake and digestion of low-quality forages, yet little is known about its impact on CH4 emissions. British-cross steers (n = 23; initial body weight [ BW ] = 344 ± 33.9 kg) were used in a three-period crossover design to evaluate the effect of protein supplementation to beef cattle consuming low-quality forage on ruminal CH4, metabolic carbon dioxide (CO2) emissions, forage intake, and ruminal fermentation. Steers individually had ad libitum access to low-quality bluestem hay (4.6% crude protein [ CP ]) and were provided supplemental protein based on (dry matter basis): cottonseed meal (CSM ; 0.29% of BW daily; 391 g/d CP), dried distillers grains with solubles (DDGS ; 0.41% of BW daily 563 g/d CP), or none (CON). Urea was added to DDGS to match rumen degradable protein provided by CSM. Ruminal CH4 and metabolic CO2 fluxes were obtained 2.4 ± 0.4 times per steer daily using an automated open-circuit gas quantification system (GreenFeed emission monitoring system; C-Lock Inc. Rapid City, SD). Forage intake increased (P < 0.01) with protein supplementation; however, no difference in forage intake (P = 0.14) was observed between CSM and DDGS treatments. Flux of CO2 (g/d) was greater (P < 0.01) for steers fed CSM and DDGS than for steers fed CON. Steers supplemented with CSM had greater (P < 0.01) CH4 emissions (211 g/d) than DDGS (197 g/d) both of which were greater (P < 0.01) than CON (175 g/d). Methane emissions as a proportion of gross energy intake (GEI) were lowest (P < 0.01) for DDGS (7.66%), intermediate for CSM (8.46%) steers, and greatest for CON (10.53%). Steers fed DDGS also had the lowest (P < 0.01) ruminal acetate:propionate ratio (3.60), whereas CSM (4.89) was intermediate, and CON (5.64) steers were greatest. This study suggests that the common practice of supplementing protein to cattle consuming low-quality forage decreases greenhouse gas emissions per unit of GEI. [ABSTRACT FROM AUTHOR]

Endometrial epithelial of cows conceiving was associated to gene set enrichment of pathways associated to synthesis, metabolism, and degradation of myo-inositol pathways (Physiol. Genomics 54: 71-85, 2022). Progesterone-modulated transcription also indicated an increase in oxidative phosphorylation pathways in the endometrial epithelial of cows. Thus, modulation of myo-inositol and oxidative phosphorylation pathways can favor conception rates in cattle. Oral supplementation with pyrroloquinoline Quinone (PQQ), an antioxidant, and inositol isomers (myo- and D-chiro-inositol) has been proven to be beneficial for fertility of women undergoing assisted reproductive biotechnologies. However, oral supplementation of these compounds to ruminant species has not been evaluated. It is unknown if PQQ and inositol isomers are soluble in the rumen environment, if they are degraded by the microbial populations which exist in this environment, or the timeframe for the ruminal degradation of these molecules resulting from oral supplementation. The objectives of this study were to 1) evaluate disappearance (solubility) of different of inositol isomers and PQQ; and 2) to quantify the in-vitro ruminal degradability of inositol isomers and PQQ over time. Inositol isomers and PQQ (0.25 g) were placed in Ankom bags and heat sealed. The bags were placed in glass beakers with an artificial saliva solution and rumen fluid, then incubated at 39 C in a warm shaker bath to simulate ruminal digestion for 0, 1, 2, 4, 8, 12, 24, and 48 h. These were then evaluated for disappearance of each form of inositol from the Ankom bag and repeated for a total of five replicates. For the second trial, only myo-inositol was evaluated. In addition to bag removal at the same time points, duplicate ruminal fluid samples were collected for myo-inositol concentration determination. This trial had seven replicates. For all forms of inositol 0.00% was removed at 0 h, and by 1 h 99.0 % inositol had disappeared (P > 0.05). There were two exceptions, PQQ, at 1 h was less (P < 0.0001; 96.33 %) and at 4 h (98.46 %). For the second trial, myo-inositol disappearance increased (P = 0.0001) from 0.00 % at 1 h to 99.53 % at 4 h and remained constant (P > 0.05) for subsequent sampling times. Ruminal fluid concentration of myo-inositol increased (P < 0.0001) from 0.197 to 5.39 g/L, and remained constant (P > 0.05) until h 24 when it had decreased (P < 0.0001) to 2.766 g/L, and decreased P < 0.0001) further by 48 h to 0.377 g/L. Ruminal concentration of myo-inositol was not different (P > 0.05) between 0 h and 48 h. These data indicates that inositol isomers and PQQ are soluble in the rumen environment, though not immediately, with myo-inositol concentrations peaking between 12 and 24 h and disappearing mostly by h 48. [ABSTRACT FROM AUTHOR]

Numerous studies have reported the negative effect of cottonseed gossypol on the ovarian reserve of the follicles, impairing female fertility. Injuries resulting in the depletion of primordial follicles can lead to permanent infertility. At birth, female mammals possess a fixed number of ovarian primordial follicles, which develop into primary, secondary, and antral follicles in a continuous and irreversible process. In this study, we evaluated the potential effects of dietary cottonseed gossypol in combination with parasitic infection on ovarian follicular reserve in meat goats. A total of 40 Boer x Spanish cross does were randomly subjected to cottonseed (CS) and parasite (P: Haemonchus contortus) in a 2x2 factorial arrangement of does (n = 8) per treatment groups (CS-/P-; CS+/P-; CS-/P+, and CS+/P+). Does were artificially infected with Haemonchus contortus for 2 d, and after 25 d, they began shedding parasite eggs. Thereafter, does were fed a hay diet supplemented with cottonseed (0.5% BW; CS+) or concentrate (CS-), to meet the nutritional requirements. Ten weeks later, animals were slaughtered, and ovaries of each treatment group (n = 4) were fixed with formalin and subjected to a standard procedure of histology staining (Periodic acid-Schiff and Hematoxylin counterstaining). Cuts of one left and one right ovary of two does were placed on microscope slides, and 48 slides were subjected to a microscope visualization (EVOS FL Auto; 20x magnification). Primordial follicles were classified as healthy (stained nucleus), unhealthy (pycnotic), and undetermined. Data were analyzed with ANOVA 1 and expressed as mean ± sem. P < 0.05 indicates a significant difference. A total of 20,562 primordial follicles corresponding to 10,410 (50.6%) healthy; 3,729 (18.1%) unhealthy; and 6,909 (33.6%) undetermined were examined; of which 26%, 20%, 31%, and 23% of total primordial follicles belonged to the CS-/P-, CS-/P+, CS+/P-, and CS+/ P+ treatment groups, respectively. A significantly (P < 0.05) greater number of follicles were counted on left vs. right ovary sections (11,584 vs. 8,978) corresponding to 56.3% vs. 43.7% of total follicle counts. Averages of 121 ± 6 vs. 101±6 follicles were calculated per left and right ovary sections. Diets containing cottonseed (CS+/P-) increased the average number of follicles per ovary section, while parasite infections significantly (P < 0.05; CS-/P+ and CS+/P+) decreased these numbers. Regardless of the treatment group, the proportions of healthy follicles remained comparable between treatment groups. We concluded that dietary cottonseed and parasitic infections inversely affect ovarian follicle reserve, while the proportions of healthy follicles were unaffected across treatment groups. Nevertheless, higher microscopic magnification is needed to better characterize the large proportion of undetermined follicles. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine the relationships among enteric gas production, body weight (BW) gain, and feed intake for growing heifers consuming two energy divergent diets. Fifty-five fall born yearling Angus and Angus cross heifers were used in a 157-d experiment. Heifers were fed two consecutive diets at the Oklahoma State University Range Cow Research Center. Heifers were sorted into one of two drylot pens based on BW. Each drylot pen was equipped with individual intake monitoring system (C-Lock Inc., Rapid City, SD) with a stocking rate of 3.3 heifers per feeder. The first intake segment (HAY) was initiated with a 21 d of adaptation followed by 70 d of data collection. Heifers were offered ad libitum access to long stem unprocessed bermudagrass hay and a salt/mineral/vitamin supplement. After the HAY period, heifers were adapted to a 50% forage, 50% concentrate diet (TMR) during a 14-d adaptation period, followed by 52-d of data collection. Means and standard deviations for phenotypic traits of DMI, ADG, RFI, and CH4 were 6.7 ± 0.7 kg, 0.44 ± 0.13kg, and 194.6 ± 17.56 g/d respectively for HAY and 14.3 ± 1.34 kg, 1.72 ± 0.20 kg, and 280 ± 24.69 g/d respectively for TMR. Pearson correlations between diets for DMI, ADG, and CH4 were 0.32, -0.16, and 0.29, respectively. Coefficient of variation for DMI was 10.8% for HAY and 9.4% for TMR. Coefficient of variation for ADG was 29.9% for HAY and 11.6% for TMR. Methane intensity was calculated as CH4, g/day divided by DMI, kg/d resulting in 29.6 ± 3.5 and 19.9 ± 2.2 g CH4/kg DMI for HAY and TMR, respectively. In summary, HAY DMI was moderately and positively correlated with TMR DMI while ADG was not correlated among the two diet types. The HAY diet generated less total daily CH4, although more CH4 per unit of feed intake. [ABSTRACT FROM AUTHOR]

Red clover (RC) contains bioactive isoflavones. Supplementing RC as a functional feed (as little as 7.5% of the total diet) has been shown to alter ruminal fermentation and improve feed efficiency in ram lambs fed high-concentrate finishing diets. The objectives of this study were to determine if reduced RC inclusion will produce similar rumen microbiological effects. It was hypothesized that RC supplementation below 7.5% RC will alter rumen microbial community composition during the finishing period. Sixteen individually housed Polypay ram lambs (age; 134 ± 2.5 d; initial body weight: 31 ± 0.53 kg) were used in a complete block design and fed one of four isocaloric and isonitrogenous diets (85:15 concentrate:roughage ratio; n = 4 rams diet): a control diet in which the roughage component (15.0% wt/wt of total diet) consisted of orchardgrass hay, 2.5%-RC (roughage: 2.5% RC; 12.5% orchardgrass wt/wt), 5.0%-RC (roughage: 5.0% RC; 10% orchardgrass wt/wt), and 7.5%-RC (roughage: 7.5% RC; 7.5% orchard grass wt/wt). Rumen fluid was collected via oral intubation at 0, 2, 4, 6, and 8 h post-feeding at the end of the adaptation period (14 d; all rams on control diet) and at 21-d intervals during the trial. Rumen functional bacterial guilds, including hyper-ammonia-producing bacteria (HAB), amylolytic, lactate-utilizing (LU), and cellulolytic bacteria were enumerated via serial dilution at 4 h post-feeding. Data were analyzed using PROC MIXED with repeated measures in SAS (v.9.4, SAS inst. Inc., Cary, NC). There were no differences between diets on d 0 for any variable (P > 0.05). At d 21, all RC-containing diets exhibited a 10- to 100-fold reduction in ruminal HAB compared with the control (P < 0.05). While suppression of HAB was no longer apparent by d 42 in 2.5%-RC, HAB had decreased 100-fold (109 to 107) in lambs fed the 5.0%-RC and 7.5%-RC diets (P < 0.01). No differences in amylolytic bacteria were detected on d 21 (P > 0.05), but were 10-fold less in all diets containing RC by d 42 in comparison with control (109 to 108; P = 0.08). In contrast, LU increased by d 21 and were 100-fold greater (106 to 108) by d 42 when compared with the control for all levels of RC supplementation (P < 0.05). Cellulolytic bacteria also increased across the study period in all lambs fed RC diets, with 100 fold greater cellulolytics (106 to 108) by d 42 (P < 0.05). Consistent with the hypothesis, supplementing RC at levels as low as 2.5% wt/wt of the total diet decreased protein-wasting HAB and amylolytic bacteria while coincidingly increasing LU and cellulolytic bacteria in the rumen. These results indicate that adding red clover to finishing diets has the potential to increase lamb growth and feed efficiency through a functional feed action. [ABSTRACT FROM AUTHOR]

The individual and combined effects of 3-nitrooxypropanol (3-NOP) and canola oil (OIL) supplementation on enteric methane (CH4) and hydrogen (H2) emissions, rumen fermentation and biohydrogenation, and total tract nutrient digestibility were investigated in beef cattle. Eight beef heifers (mean body weight ± SD, 732 ± 43 kg) with ruminal fistulas were used in a replicated 4 × 4 Latin square with a 2 (with and without 3-NOP) × 2 (with and without OIL) arrangement of treatments and 28-d periods (13 d adaption and 15 d measurements). The four treatments were: control (no 3-NOP, no OIL), 3-NOP (200 mg/kg dry matter [ DM ]), OIL (50 g/kg DM), and 3-NOP (200 mg/kg DM) plus OIL (50 g/kg DM). Animals were fed restrictively (7.6 kg DM/d) a basal diet of 900 g/kg DM barley silage and 100 g/kg DM supplement. 3-NOP and OIL decreased (P < 0.01) CH4 yield (g/kg DM intake) by 31.6% and 27.4%, respectively, with no 3-NOP × OIL interaction (P = 0.85). Feeding 3-NOP plus OIL decreased CH4 yield by 51% compared with control. There was a 3-NOP × OIL interaction (P = 0.02) for H2 yield (g/kg DM intake); the increase in H2 yield (P < 0.01) due to 3-NOP was less when it was combined with OIL. There were 3-NOP × OIL interactions for molar percentages of acetate and propionate (P < 0.01); individually, 3-NOP and OIL decreased acetate and increased propionate percentages with no further effect when supplemented together. 3-NOP slightly increased crude protein (P = 0.02) and starch (P = 0.01) digestibilities, while OIL decreased the digestibilities of DM (P < 0.01) and neutral detergent fiber (P < 0.01) with no interactions (P = 0.15 and 0.10, respectively). 3-NOP and OIL increased (P = 0.04 and P < 0.01, respectively) saturated fatty acid concentration in rumen fluid, with no interaction effect. Interactions for ruminal trans -monounsaturated fatty acids (t-MUFA) concentration and percentage were observed (P = 0.02 and P < 0.01); 3-NOP had no effect on t-MUFA concentration and percentage, while OIL increased the concentration (P < 0.01) and percentage (P < 0.01) of t-MUFA but to a lesser extent when combined with 3-NOP. In conclusion, the CH4-mitigating effects of 3-NOP and OIL were independent and incremental. Supplementing ruminant diets with a combination of 3-NOP and OIL may help mitigate CH4 emissions, but the decrease in total tract digestibility due to OIL may decrease animal performance and needs further investigation. [ABSTRACT FROM AUTHOR]

The effects of live yeast and diet type (grower or finisher) offered to beef steers on feeding behavior were evaluated. Eight ruminally cannulated yearling beef steers (BW = 550 ± 20 kg) were used in a duplicated 4 × 4 Latin Square design and offered four dietary treatments to ad libitum intake, following a 2 × 2 factorial treatment arrangement: A) presence or not of live-yeast Saccharomyces cerevisiae [2 × 1010 CFU/g (CNCM I-1077)]; and B) diet type. Diets (DM basis) contained 3% yellow-grease and mineral/vitamin supplement-adjusted. The grower [40% low-quality alfalfa-hay (LQ-hay), 35% steam-flaked corn (SFC), 20% wet corn gluten feed (WCGF)] and finisher (65% SFC, 20% WCGF, 8% LQ-hay) diets were offered once daily at 0700 h. Live-yeast cells or placebo (soybean meal) were delivered with gel capsules (0.25 g, as is) twice daily directly into the rumen via ruminal cannula. Four, 35 d periods were used, in which feeding behavior assessment was conducted by trained personnel on d 31 (continuous 24 h, every 5 min) while no other major management was performed during the evaluation. The time spent eating, ruminating (standing/laying), resting (stating/laying), active, and drinking were recorded, while chewing was estimated by adding rumination and eating time. The number of meals and time spent on each meal were also assessed. Data were analyzed using the GLIMMIX procedures of SAS, with animal considered as the experimental unit. The statistical model used the fixed effects of diet type, liveyeast presence, and the diet × live-yeast interaction, while square, period, and animal(square) were used as random effects. No diet × live-yeast interactions (P = 0.17) or main effects of live-yeast (P = 0.23) were observed for the variables measured. Feeding behavior was affected by diet type, in which steers offered a grower diet had greater time spent ruminating (341 vs. 231 min/d; P < 0.01), eating (154 vs. 105 min/d; P < 0.01), chewing (494 vs. 336 min/d; P < 0.01), and meal length (13 vs. 10 min/meal; P < 0.01), while less time resting (838 vs. 973 min/d; P < 0.01) compared with those offered the finisher diet. The time spent drinking (15 min/d; P = 0.29) and the number of daily meals (13 meals/d; P = 0.66) were not affected by treatments, while steers offered the finisher diet tended (P = 0.12) to be more active than those offered the grower diet (116 vs. 95 min/d). As expected, grower diets were more prone than finisher diets to stimulate feeding behavior variables of beef steers. Moreover, when directly introduced inside the rumen via ruminal cannula, the live yeast used seemed to not affect the feeding behavior of beef steers consuming a steam-flaked corn-based grower or finisher diet. [ABSTRACT FROM AUTHOR]

Phytogenic additives are used as food additives in ruminant nutrition due to their potential to alter the nitrogen (N) excretion route and minimize N emissions into the environment. This study aimed to evaluate the effect of two levels of supplementation plus a mixture of phytogenic additives (essential oils, saponins and spices) on the efficiency of N utilization by beef cattle in tropical pastures. The experiment was conducted at the Beef Cattle Sector of UNESP, Jaboticabal-BR, and lasted 84 days. Nine castrated Nelore steers (body weight 262 ± 31.2 kg) cannulated in the rumen were distributed in 3 simultaneous 3 × 3 Latin square designs. The animals were kept in pasture of Urochloa brizantha cv. Marandu during the rainy season. Treatments included ad libitum mineral supplementation (MS) as a control group, mineral supplementation added 0.1% of body weight per day plus Cargill phytogenic mixture (AMSP) and energyprotein supplementation, 0.3% of body weight per day plus Cargill phytogenic mixture (EPSP). Point urine and fecal samples were collected in the last three days of each experimental period. The concentration of total nitrogen in the urine was analyzed by the Kjeldahl procedure. The nitrogen composition of forage, supplements and feces was estimated by near-infrared spectroscopy (NIRS) using a modular FT-NIR spectrometer (NIRFlex N500, Büchi Labortechnik AG, Flawil, Switzerland). Nitrogen retention was calculated using the following equation: NR = N intake (g/d) - [N excretion in feces (g/d) + N excretion in urine (g/d)]. The nitrogen metabolism data were analyzed as a 3 × 3 Latin square with 3 replications, balanced for residual effects. Considering as fixed effect the treatment, and as random effect the Latin square, period, steer, steer × period interaction, and residues corresponding to the model. The data obtained were submitted to ANOVA and Tukey's test (P = 0.05), using the statistical program R, version 3.4.4. The addition of phytogenic additives in the supplements led to decreased (P < 0.036) urinary excretion of N (g/day) from 41.16 g/day to 28.38 g/day and urinary excretion of N (% of N intake) from 30.66% to 23.21%, but did not differ between the different levels of phytogenic supplementation (Table 1). In addition, retained N (% of N intake) was greater (P < 0.01) in animals supplemented with AMSP and EPSP compared with MS, increasing N retention from 26.78% to 33.88%. This study indicates that the different levels of supplementation plus the addition of the phytogenic mixture improved the efficiency of N utilization by decreasing the excretion of N in the urine and increasing the retained N compared with MS supplementation. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of a postbiotic feeding program consisting of liquid and solid Saccharomyces cerevisiae fermentation products (SCFP) on digestibility, ruminal fermentation, and plasma metabolome of finishing beef steers. Eight Holstein steers (BW 467 ± 13.9 kg) equipped with rumen cannulas were used in a crossover design study, with 21-d per period and 7-d washout period in between periods. Steers were blocked based on initial BW to one of two treatments: 1) Control, basal diet only (CON), or 2) SCFP, one day feeding of LiquiCare RTU (Diamond V, dosed via rumen cannula at 11 mL/100 kg BW) followed by daily feeding of 12 g NaturSafe (Diamond V, top-dressed). Feed and fecal samples were collected during d 17 to 20 for determination of digestibility and fecal excretion of N, P, Cu and Zn using acid-insoluble ash as an internal marker. Blood samples were collected on d 21 before morning feeding. Rumen fluid samples were collected on d 0, 1, 2, 3, 5 and 21 at 0, 4, 8, or 12 h post morning feeding via rumen cannula. Results were analyzed with the GLIMMIX procedure of SAS 9.4 (SAS, 2022). BW, DMI and digestibility were not affected by treatment. There was a tendency of treatment by period interaction (P = 0.09) on feed efficiency, which was improved by feeding SCFP only in period 1. Feeding SCFP did not affect (P > 0.10) ruminal pH. Feeding SCFP tended to reduce ruminal lactate concentration on d 21 (0.09 vs. 0.02 mM, P = 0.10). Supplementing SCFP reduced ruminal NH3-N concentration on d 2 (4.24 vs. 7.31 mg/dL, P = 0.03) and d 21 (4.86 vs. 6.83 mg/dL, P = 0.04). By feeding SCFP, ruminal total VFA concentration was increased 4-h post-feeding on d 5 (139.7 vs. 126.7 mM, P = 0.01) and numerically increased 4-h post-feeding on d 21 (151.2 vs. 133.3 mM, P = 0.12). For VFA composition, no treatment differences were observed on day 21. However, feeding SCFP reduced (P = 0.01) propionate proportion and increased (P = 0.05) butyrate proportion on day 3. The enriched plasma metabolic pathways (P ≤ 0.05) by feeding SCFP are citric acid cycle, pyrimidine metabolism, glycolysis/gluconeogenesis, retinol metabolism, and inositol phosphate metabolism pathways. Overall, our results indicated potential benefits of the SCFP feeding program on improving ruminal fermentation, preventing acidosis and improving N utilization in the rumen. Furthermore, feeding SCFP enriched several important pathways in lipid, protein, and glucose metabolism, which may improve feed efficiency of energy and protein in finishing beef cattle. [ABSTRACT FROM AUTHOR]

We applied metabolomics and 16S rRNA gene sequencing to determine the metabolic pathway and ruminal bacterial taxa associated with divergent residual body weight (BW) gain phenotype in crossbred beef steers. A group of 108 crossbred growing beef steers (average BW = 282.87 ± 30 kg) were fed a forage-based diet for a period of 56 d in a confinement dry lot equipped with GrowSafe intake nodes to determine their residual body weight gain (RADG) phenotype. After RADG identification, blood and rumen fluid samples were collected from beef steers with the greatest RADG (most efficient; n = 20; 0.76 kg/d) and least RADG (least efficient; n = 20; -0.65 kg/d). Metabolome analysis of the plasma and rumen fluid samples was conducted using chemical isotope labelling/liquid chromatography-mass spectrometry. Differentially abundant metabolites in each of the plasma and rumen fluid samples between the two groups of beef steers were determined using a false discovery rate (FDR)-adjusted P-values ≤ 0.05 and area under the curve (AUC) > 0.80. Rumen and plasma metabolic pathways that were differentially enriched or depleted (P ≤ 0.05) in beef steers with positive RADG compared with those with negative RADG were determined by the quantitative pathway enrichment analysis. A total of 1,629 metabolites were detected and identified in the plasma of the beef steers; eight metabolites including alanyl-phenylalanine, 8-hydroxyguanosine, and slaframine were differentially abundant (FDR ≤ 0.05; AUC > 0.80) in beef steers with divergent RADG; five metabolic pathways including steroid hormone biosynthesis, thiamine metabolism, propanoate metabolism, pentose phosphate pathway, and butanoate metabolism were enriched (P ≤ 0.05) in beef steers with positive RADG, relative to negative RADG steers. A total of 1908 metabolites were detected and identified in the rumen of the beef steers; results of the pathway enrichment analysis of all the metabolites revealed no metabolic pathways in the rumen were altered (P = 0.05). The rumen fluid samples were also analyzed using 16S rRNA gene sequencing to assess the bacterial community composition. We compared the rumen bacterialcommunity composition at the genus level using a linear discriminant analysis effect size (LEfSe) to identify the differentially abundant taxa between the two groups of beef steers. The LEfSe results showed greater relative abundance of Bacteroidetes_vadinHA17 and Anaerovibrio in steers with positive RADG compared with the negative RADG group, while steers in the negative RADG group had greater relative abundance of Candidatus_Amoebophilus, Clostridium_sensu_ stricto_1, Pseudomonas, Empedobacter, Enterobacter, and Klebsiella compared with the positive RADG group. Our results demonstrate that beef steers with positive or negative RADG exhibit differences in plasma metabolic profiles and some ruminal bacterial taxa which probably explain their divergent feed efficiency phenotypes. [ABSTRACT FROM AUTHOR]

The objective of the study was to optimize and improve the feeding value of corn stover. Despite the documented ability of Pleurotus ostreatus to selectively delignify crop residues, it is not widely used for ruminant fiber digestion partly due to extended pretreatment time. Optimization of crop residues is influenced by enzymatic activities of fiber degrading enzymes and dependent on the stage of P. ostreatus growth. Thus, optimizing the inoculation period for lignin removal by P. ostreatus is important to improve and increase success on lignocellulose feed resources utilization. Therefore, we hypothesized a difference in nutritive value for different inoculation periods for P. ostreatus spent substrates. Two ruminally cannulated dairy cows were used in an in vitro study arranged in a 3 x 5 factorial design with 4 replicates to evaluate the effects of inoculation period [0 (control), 2, 4, 6 and 8 wk] on P. ostreatus spent substrates at 6, 24 and 48 h of fermentation on chemical composition, dry matter disappearance (DMd) and volatile fatty acid (VFA) production. Significant (P < 0.001) non-linear treatment effect across the inoculation period was observed in the treated samples (Table 1). An increase of 44.4 to 59.1% and 20.6 to 78.6% was noted for the crude protein and ash contents, respectively. Also, significant (P < 0.001) incubation time effect across the inoculation period resulted in a wide variation (22.6 - 755%) in the microbial mass with greater values for 2- and 4-wk treatments. Neutral detergent fiber and hemicellulose were significantly (P < 0.001) reduced with a range between 7.29 to 18.7% and 26.6 to 40.8%, respectively (Table 3). Inconsistent positive and negative outcomes across the periods in acid detergent fiber, lignin and cellulose resulted in significant (P < 0.001) 116 and 121% increment in non-fiber carbohydrates for 2 and 4-wk treatments, respectively. Consequently, both DMd and total VFA were significantly (P < 0.001) greater, ranging between 238 to 242% and 13.9 to 15.1% respectively for these treatments (Table 2). Additionally, the rumen fermentation pathway favored production of propionate with significant (P < 0.001) treatment and time effect that resulted in 7.46 and 8.30% increment in propionate production after 2 and 4 wk, respectively. Consequently, significant (P < 0.001) reduction was observed in acetate with 4.44 and 3.58%, and 11.7 and 11.1% in A:P ratio for 2 and 4 wk, respectively. High butyrate production was observed for 2 wk in comparison with 4 wk resulting in 18.3 and 9.86% increment, respectively, when compared with control (Table 4). The study showed that 2 wk of inoculation is sufficient to provide bio-transformed cow-calf feed resource from P. ostreatus treated corn stover, which is contrary to 30 days (4 wk) previously recommended. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate effects of increasing hybrid rye as a replacement for barley grain on feed intake, ruminal fermentation, and site of nutrient digestion in finishing cattle. Eight ruminally and duodenally cannulated Hereford-cross heifers (starting body weight = 514 ± 25.3 kg) were used in a replicated 4×4 Latin square design with 21-d periods including 15 d of dietary adaptation and 6 d of sample collection. Dietary treatments included a control diet with 10.0% hay, 85.2% barley grain, and 4.8% of a vitamin and mineral supplement on a dry matter (DM) basis. Hybrid rye grain replaced 33, 67, or 100% of the barley grain. Both cereal grains were dry rolled to 80% processing index. Feed, refusals, ruminal fluid, duodenal digesta, and fecal samples were collected. Data were analyzed using the MIXED procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC). Increasing hybrid rye inclusion tended (P = 0.052) to linearly decrease DM intake. Additionally, increasing hybrid rye grain linearly decreased mean and minimum ruminal pH (P < 0.01) and increased the duration (P < 0.01) and area (P = 0.01) that pH was less than 5.5. There was no effect of hybrid rye inclusion on total short chain fatty acid, lactic acid concentrations, or osmolality. Likewise, the molar proportion of acetate and butyrate were not affected by hybrid rye inclusion. Propionate tended to linearly increase with increasing hybrid rye inclusion (P = 0.08). Increasing hybrid rye linearly increased NH3-N concentration (P = 0.03). Ruminal organic matter (OM) digestibility tended to linearly increase (P = 0.08) and ash-free neutral detergent fiber (aNDFom) digestibility linearly increased (P < 0.01) when increasing hybrid rye. There was no effect on ruminal starch digestibility (71.1 ± 5.12%). Intestinal digestibility of CP linearly decreased (P = 0.050), but there were no effects for other nutrients. Increasing hybrid rye linearly increased apparent total-tract DM, OM, and aNDFom digestibility (P < 0.05) but did not affect starch digestibility (97.4 ± 0.42%). Increasing the inclusion rate of hybrid rye grain at the expense of barley grain in finishing diets may decrease DMI and increase risk for ruminal acidosis; however, hybrid rye inclusion did not influence the site or extent of starch digestion and increased total tract digestibility of DM, OM, and aNDFom. [ABSTRACT FROM AUTHOR]