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Forages and concentrates have consistently distinct patterns of fermentation in the rumen, with forages producing more methane (CH4) per unit of digested organic matter (OM) and higher acetate to propionate ratio than concentrates. A mechanism based on the Monod function of microbial growth has been proposed to explain the distinct fermentation pattern of forages and concentrates, where greater dilution rates and lower pH associated with concentrate feeding increase dihydrogen (H2) concentration through increasing methanogens growth rate and decreasing methanogens theoretically maximal growth rate, respectively. Increased H2 concentration would in turn inhibit H2 production, decreasing methanogenesis, inhibit H2-producing pathways such as acetate production via pyruvate oxidative decarboxylation, and stimulate H2-incorporating pathways such as propionate production. We examined the hypothesis that equalizing dilution rates in serial rumen cultures would result in a similar fermentation profile of a high forage and a high concentrate substrate. Under a 2 × 3 factorial arrangement, a high forage and a high concentrate substrate were incubated at dilution rates of 0.14, 0.28, or 0.56 h-1 in eight transfers of serial rumen cultures. Each treatment was replicated thrice, and the experiment repeated in two different months. The high concentrate substrate accumulated considerably more H2 and formate and produced less CH4 than the high forage substrate. Methanogens were nearly washed-out with high concentrate and increased their initial numbers with high forage. The effect of dilution rate was minor in comparison to the effect of the type of substrate. Accumulation of H2 and formate with high concentrate inhibited acetate and probably H2 and formate production, and stimulated butyrate, rather than propionate, as an electron sink alternative to CH4. All three dilution rates are considered high and selected for rapidly growing bacteria. The archaeal community composition varied widely and inconsistently. Lactate accumulated with both substrates, likely favored by microbial growth kinetics rather than by H2 accumulation thermodynamically stimulating electron disposal from NADH into pyruvate reduction. In this study, the type of substrate had a major effect on rumen fermentation largely independent of dilution rate and pH.

The physical attributes of corn silage are enhanced by shredlage (SHR), while there is a rising interest in boosting its biological performance. This study aimed to assess and compare the impact of both the chopping method and different yeast strains on ensilage quality including the in vitro evaluation of corn silage. Both types of corn, including chopped and shredded, were harvested on the same day from the same field where the same corn hybrid (Suwan 5) was grown. Subsequently, whole-corn plants were fermented with additives. A 2 × 5 Factorial completely randomized design was employed, where factor A represents corn chopped (CON) and corn shredded (SHR), and factor B represents the additives: no additives, molasses + urea (M + U), M + U + Candida tropicalis KKU20, M + U + Pichia kudriavzevii KKU20, and M + U + saccharomyces cerevisiae. The results demonstrated that SHR fermentation with M + U and yeast significantly increased in vitro dry matter degradability (IVDMD) and organic matter degradability (IVOMD). Specifically, at 4 h post-incubation, the addition of Crabtree-negative yeast led to a 5.8% increase in total volatile fatty acids (TVFA) compared to the Crabtree-positive yeast group (P < 0.01). The C2 (acetic acid) + C4 (normal butyric acid and isobutyric acid): C3 (propionic acid) ratio showed a significant decrease without additives, but P. kudriavzevii KKU20 led to the highest ratio and methane production (P < 0.01). Based on this study, it could be concluded that SHR harvesting led to higher digestion efficiency in the rumen. The use of M + U + yeast also demonstrated uncertain effects on rumen fermentation efficiency, and the inclusion of P. kudriazevii KKU20 may potentially reduce rumen fermentation efficiency when used with corn silage. [ABSTRACT FROM AUTHOR]

Objective: Nicotinamide (NAM) is easily degraded in the rumen, but the rumen-protected NAM (RPN) supplementation might enable the use of NAM in ruminants. This study aimed to elucidate the effects of RPN supplementation on growth performance, rumen fermentation, antioxidant status and amino acid (AA) metabolism in growing lambs. Methods: A total of 128 healthy and similar lambs (21.3±0.28 kg, 70±6.3 days of age) were allotted to 1 of 4 groups. The treatments were 0, 0.5, 1, and 2 g/d RPN supplementation. The RPN products (50% bioavailability) were fed at 0700 h every day for 12 weeks. All lambs were fed the same pelleted total mixed rations to allow ad libitum consumption and had free access to water. Results: The RPN tended to increase the average daily gain and feed efficiency. The tendencies of RPNxday interaction were found for dry matter intake during the entire study (p = 0.078 and 0.073, respectively). The proportions of acetic acid, isobutyric acid and isovaleric acid were decreased, whereas the proportions of propionic acid and valeric acid were increased (p<0.05). The ratio of acetic acid to propionic acid was decreased (p<0.05). Moreover, the antioxidative status was enhanced and the glucose concentration was increased by RPN (p<0.05). In addition, 17 AAs were detected in plasma, of which 11 AAs were increased by RPN (p<0.05). Plasma metabolomics analysis identified 1,395 compounds belonging to 15 classes, among which 7 peptides were significantly changed after RPN supplementation. Conclusion: Overall, the results suggested that RPN supplementation favoured the rumen fermentation pattern to propionic acid-type with benefited glucose metabolism, enhanced antioxidant capacity, and changed the AA and small peptide metabolism. This study provides a new perspective for studying the relationship between vitamin and AA metabolism. [ABSTRACT FROM AUTHOR]

The present study investigated the effects of water extracts of Artemisia annua L. (WEAA) on rumen immune and antioxidative indexes, fermentation parameters and microbial diversity in lambs. A total of 32 3-month-old Dorper × Han female lambs having comparable body weights (24±0.09 kg) were selected and were randomly assigned to four treatments, with eight repetitions for each treatment. The basal diet, consisting of 45% concentrate and 55% forage, was solely provided to the control group. For the other treatment groups, the basal diet was supplemented with WEAA at dosages of 500, 1000, and 1500 mg/kg diet, respectively. Rumen tissue samples were collected for the analysis of immune and antioxidative parameters, as well as related gene expression. Rumen fluid samples were collected to assess rumen fermentation parameters on days 30 and 60 and to evaluate the microbiota on day 60. Results showed that WEAA supplementation linearly or quadratically increased the content of sIgA, IL-4, IL-2 and the gene expression level of MyD88, IκB-α, IL-4, COX-2, iNOS in rumen tissue (p < 0.05), as well as the bacteria negatively associated with IL-6 (g_ [Eubacterium] _cellulosolvens_group). Furthermore, the addition of WEAA linearly or quadratically increased rumen T-SOD, GSH-Px (p < 0.05) and the gene expression level of Nrf2, SOD2, GSH-Px, HO-1 (p < 0.05), and decreased the rumen concentration of malondialdehyde (MDA) and gene expression level of Keap1 (p < 0.05), as well as the bacteria positively associated with T-AOC, T-SOD and GSH-Px (g_Lachnospiraceae_NK3A20_group, g_Saccharofermentans, g__Marvinbryantia, g_unclassified_f_Eggerthellaceae). The supplementation of WEAA caused the concentration of microprotein (MCP), total volatile fatty acids (TVFA), propionate to increase either linearly or quadratically, while reducing the concentration of NH3-N and the acetate/propionate ratio (A:P) in rumen fluid (p < 0.05). The addition of WEAA linearly or quadratically increased the abundance of Actinobacteriota, Cyanobacteria and Lachnospiraceae_NK3A20_group (p < 0.10), and g__Lachnospiraceae_NK3A20_group, g_Saccharofermentans, g_Marvinbryantia, g_Bifidobacterium were significantly abundant as specific microflora in the 1000 mg/kg WEAA supplementation group. In conclusion, dietary inclusion of 1000 mg/kg WEAA improved the rumen immune function, antioxidant status, rumen fermentation, and composition of rumen microbes in lambs. [ABSTRACT FROM AUTHOR]

Rosa roxburghii tratt residue (RRTR) is a regional and uncommon byproduct in Guizhou. Little information is available on whether RRTR can be used as feed for ruminants. In this study, the feasibility of using RRTR as a new feed resource for cattle was investigated by chemical composition analysis, in vitro gas production (Trial 1) and animal feeding experiments (Trial 2). In trial 1, compared to the commonly used fruit residues, RRTR had a proximate nutrient level; the in vitro gas production curve and dynamics fell within the normal range. In trial 2, 16 cattle were allocated to the control and treatment groups, with 8 replicates of 1 cattle each. Cattle in the control group were fed a basal diet without RRTR, while those in the treatment group were fed a diet containing 30% RRTR to replace 30% whole corn silage in basal diet. Feeding RRTR had little effect on the growth performance of the control and treatment cattle (P > 0.05). The feed-to-gain ratio was greater in the treatment group than in the control group throughout the trial period (P < 0.05). The plasma urea levels in the treatment group were lower (P < 0.05) than that in control group, and the levels of other plasma biochemical metabolites were not different between the two groups of cattle (P > 0.05). The in vivo rumen fermentation parameters did not differ between the control and treatment groups (P > 0.05). Our findings indicate that RRTR has a nutritional profile (crude protein, neutral detergent fiber, acid detergent fiber, and crude fiber) similar to that of commonly used fruit residues (such as apple, pineapple, and citrus residue et al.); improves plasma protein utilization efficiency; and has no negative impact on growth performance, albeit with limited effects on feed conversion; blood metabolites, and rumen fermentation parameters in cattle. Accordingly, we conclude, based on the above-mentioned result, that RRTR can serve as a novel feed alternative resource when considering the affordability and as a practical choice for low-cost diets for cattle. [ABSTRACT FROM AUTHOR]

Ruminant animals constitute major contributors to greenhouse gas (GHG) emissions and play an important part in sustainable agricultural systems. A bioactive compound (BC) with antibacterial properties was utilized to inhibit rumen methanogens and decrease ruminant methane emissions. The bio efficacy of ruminant nutrition was frequently employed using a new technology through microencapsulation technique to produce stable products. The microencapsulated banana flower powder pellet (mBAFLOP) powder was used as a BC in the diets. Consequently, this study aimed to evaluate the effects of mBAFLOP supplementation on in vitro gas production kinetics, rumen fermentation, microbial population, and methane production. A completely randomized design (CRD) was used to randomly assign respective treatments at 0, 1, 2, and 3% of the total dry matter (DM) substrate. Ruminal pH, in vitro dry matter degradability and volatile fatty acid profile both at 12, and 24 h were not negatively affected by supplementation with mBAFLOP. The supplemented mBAFLOP (3% of total DM substrate) resulting in ruminal ammonia-nitrogen concentrations was linearly increased (P < 0.01) different among treatments, while methane production was reduced when compared with other treatment (quadratic effect, P < 0.05). Moreover, Ruminococcus flavefaciens was increased when the proportion of mBAFLOP supplement was increased. Furthermore, there was a linear effect (P < 0.05) of decreasing Methanobacteriales in the rumen with increased levels of mBAFLOP supplementation. Based on this study, the use of mBAFLOP at 3% could enhance NH3N concentration and cellulolytic bacteria especially Ruminococcus flavefaciens was increased. Furthermore, supplementation with mBAFLOP decreased methane production. Therefore, a possible dietary plant-based bioactive compound, mBAFLOP supplementation cloud enhances rumen fermentation and mitigates methane production. [ABSTRACT FROM AUTHOR]

The objective was to assess the supplementation with microencapsulation of hemp leaf extract (mHLE) utilized as a rumen enhancer on in vitro rumen fermentation and to enhance the bioavailability of active compounds for antimicrobial action, particularly in protozoa and methanogen populations. The feed treatments were totally randomized in the experimental design, with different levels of mHLE diet supplemented at 0, 4, 6 and 8% of total DM substrate and added to an R:C ratio of 60:40. During fermentation, gas kinetics production, nutrient degradability, ammonia nitrogen concentration, volatile fatty acid (VFA) profiles, methane production, and the microbial population were measured. The supplemented treatment at 6% of total DM substrate affected reductions in gas kinetics, cumulative gas production, and volatile fatty acid profiles, especially the acetate and acetate to propionate ratio. Whereas propionate proportion and total volatile fatty acid concentration were enhanced depending on the increase of nutrients in vitro dry matter degradability (IVDMD) after 12 h of post-fermentation at a R:C ratio of 60:40 (P < 0.05). Consequently, mHLE addition resulted in optimal ruminal pH and increased nutrient degradability, followed by ammonia nitrogen concentrations (P < 0.05), which were enhanced by dominant cellulolytic bacteria, particularly Ruminococcus albus and Ruminococcus flavefaciens, which showed the highest growth rates in the rumen ecology. Therefore, mHLE, a rich phytonutrient feed additive, affected the methanogen population, reduced the calculated methane production and can be a potential supplement in the ruminant diet. [ABSTRACT FROM AUTHOR]

Background: The rumen microbiome plays an essential role in maintaining ruminants' growth and performance even under extreme environmental conditions, however, which factors influence rumen microbiome stability when ruminants are reared in such habitats throughout the year is unclear. Hence, the rumen microbiome of yak (less domesticated) and cattle (domesticated) reared on the Qinghai-Tibetan Plateau through the year were assessed to evaluate temporal changes in their composition, function, and stability. Results: Rumen fermentation characteristics and pH significantly shifted across seasons in both cattle and yak, but the patterns differed between the two ruminant species. Ruminal enzyme activity varied with season, and production of xylanase and cellulase was greater in yak compared to cattle in both fall and winter. The rumen bacterial community varied with season in both yak and cattle, with higher alpha diversity and similarity (beta diversity) in yak than cattle. The diversity indices of eukaryotic community did not change with season in both ruminant species, but higher similarity was observed in yak. In addition, the similarity of rumen microbiome functional community was higher in yak than cattle across seasons. Moreover, yak rumen microbiome encoded more genes (GH2 and GH3) related to cellulose and hemicellulose degradation compared to cattle, and a new enzyme family (GH160) gene involved in oligosaccharides was uniquely detected in yak rumen. The season affected microbiome attenuation and buffering values (stability), with higher buffering value in yak rumen microbiome than cattle. Positive correlations between antimicrobial resistance gene (dfrF) and CAZyme family (GH113) and microbiome stability were identified in yak, but such relationship was negatively correlated in cattle. Conclusions: The findings of the potential of cellulose degradation, the relationship between rumen microbial stability and the abundance of functional genes varied differently across seasons and between yak and cattle provide insight into the mechanisms that may underpin their divergent adaptation patterns to the harsh climate of the Qinghai-Tibetan Plateau. These results lay a solid foundation for developing strategies to maintain and improve rumen microbiome stability and dig out the potential candidates for manufacturing lignocellulolytic enzymes in the yak rumen to enhance ruminants' performance under extreme environmental conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: Dietary composition is the main factor regulating the rumen microflora structure and fermentation mode. The change of the concentrate to roughage ratio of diets can cause the change of rumen microflora and affect the feed utilization and growth performance of ruminants. This study investigated the effects of the extreme transition from all-concentrate to all-roughage diets on the patterns and functions of the rumen microbiome in high-altitude yaks, cattle-yak, Tibetan yellow cattle and low-altitude yellow cattle by metagenomic sequencing. After diet conversion, the rumen microbial richness and diversity of the four herds increased, and the biggest difference between concentrate and roughage diets was yak and cattle-yak, followed by Tibetan yellow cattle and yellow cattle. The transformation in diets can change the metabolic pathways of rumen microorganisms in four herds and finally affect the fermentation mode of rumen. Compared with Tibetan yellow cattle and yellow cattle, yaks and cattle-yaks have better adaptability to roughage, and its utilization rate can be fully improved to reduce methane emission, and they are more suitable for intensive feeding on the plateau. The experiment was to compare the effects of switching all-concentrate to all-roughage diets on rumen microflora and functional metabolism of yak, cattle-yak, Tibetan yellow cattle and yellow cattle living in different altitudes. A total of 24 yaks, cattle-yaks, Tibetan yellow cattle and yellow cattle with a similar weight and good body condition aged 3.5 years were selected and divided into four groups according to species. They were fed a concentrate diet with 40% soybean meal and 60% corn meal for the first month (C group) and a roughage diet with dry corn stalks (100%) for the second month (R group); the formal experimental period was 60 d. These results showed that the conversion had a significant effect on the rumen microflora structure of the four herds, and the biggest difference between concentrate and roughage diets was yak and cattle-yak, followed by Tibetan yellow cattle and yellow cattle. At the phylum level, Bacteroidetes and Firmicutes still predominate in all groups. Compared with the C groups, the relative abundance of Lentisphaerae and Kiritimatiellaeota increased in all R groups, and Lentisphaerae was significantly increased in yak and cattle-yak (p < 0.05). At the genus and species levels, Prevotella had the highest abundance, and the relative abundances of Prevotella, Ruminococcus, Sarcina and Ruminobacter in R groups were lower, while the abundances of other differential genera, including Methanobrevibacter, Fibrobacter, Treponema, Eubacterium, Butyrivibrio, Succinivibrio and Succinimonas, were all higher. Roughage diets increased the number of unique genes and functional genes encoding different CAZymes in rumen microorganisms in all four herds. In the functional contribution analysis, with the exception of ABC transporters and methane metabolism, Prevotella was the main contributor to almost all of these functions. In methane metabolism, Methanobrevibacter had the highest relative abundance, followed by Prevotella, Clostridia and Bacteroidales in all groups. Compared with Tibetan yellow cattle and yellow cattle, yaks and cattle-yaks have better adaptability to roughage, and its utilization rate can be fully improved to reduce methane emission. The study indicates that when four herds are converted to high roughage at the later stage of feeding, the growth and reproduction of rumen microorganisms are affected, and the abundance and diversity of rumen microorganisms are increased to varying degrees. The transformation of concentrate to roughage diet can change the metabolic pathways of rumen microorganisms in yaks and finally affect the fermentation mode of rumen. The above results provide a theoretical basis for the research and development of fattening feeds for yaks, cattle-yaks, Tibetan yellow cattle and yellow cattle and the intensive feeding of livestock on the plateau. [ABSTRACT FROM AUTHOR]

ABSTRACT Recently, the potential of using chitosan (CHI) as a feed additive to enhance ruminal fermentation and improve animal performance has gained increasing attention in ruminant nutrition. This study was undertaken to investigate the effect of dietary supplementation with increasing doses of CHI on rumen fermentation attributes and microbial composition, digestibility and milk performance in Dhofari goats. Twenty‐four lactating goats (27 ± 1.8 kg of initial live body weight) were fed a control diet comprising of Rhodes grass hay plus a concentrate feed mixture. Goats were assigned to one of three experimental treatments (n = 8 per treatment) as: (1) control diet with no supplement (CTRL), (2) control diet with 0.300 g/day CHI (CHI0.3) and (3) control diet supplemented with 0.600 g/day CHI (CHI0.6) for a 45‐day experimental period. Dietary supplementation with increasing doses of CHI decreased (p < 0.05) linearly ruminal pH (p = 0.023), total short chain fatty acids concentrations (p = 0.011), acetate (p = 0.013) and butyrate (p = 0.042) proportions, acetate to propionate ratio (p < 0.001), estimated methane (CH4) production (p < 0.001), ammonia nitrogen concentrations (p = 0.003) and protozoa abundance (p = 0.003). However, the ruminal propionate proportion augmented (p = 0.002) linearly with increasing doses of CHI in the diet. Increasing doses of CHI linearly increased the abundance of the ruminal propionate‐producing bacteria, while diminished acetate and CH4‐producing bacteria (p < 0.05). Serum total protein (p = 0.037) and glucose (p = 0.042) levels linearly increased as CHI doses increased in the diet. However, serum UREA levels decreased linearly (p = 0.002) by 21% with increasing CHI amounts in the diet. The digestibility of organic matter, crude protein and neutral detergent fibre increased linearly with the increasing CHI doses (p < 0.05). Neither linear nor quadratic responses (p > 0.05) were observed in daily milk yield and feed efficiency by supplementing the diet with CHI. In conclusion, supplementing the diet with CHI at a dose of 0.600 g/day as a feed additive for dairy goats reduced estimated CH4 generation and improved fibre and protein digestion, with no influence on feed intake, milk yield or composition. [ABSTRACT FROM AUTHOR]

Introduction: Pregnancy toxemia (PT) is a nutritional metabolic disease of ewes in late pregnancy. This study aimed to reveal the relationship between rumen microbiota and PT. Methods: We selected 10 healthy ewes (CON) and 10 pregnancy toxemia ewes (PT) at 135 days of gestation according to the blood ß-hydroxybutyrate (BHBA), glucose (Glu) concentrations and clinical symptoms. Blood and rumen fluid were collected before morning feeding to determine serum biochemical indices and rumen fermentation parameters. Total DNA of rumen fluid was extracted and the V3-V4 regions of 16S rRNA were amplified by PCR for high-throughput sequencing. Results: The results showed that the serum concentrations of Glu, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), uric acid (UA), creatinine (Cr), acetate, propionate, butyrate, and microbial crude protein (MCP) were decreased (p < 0.05) and the concentrations of BHBA, aspartate aminotransferase (AST), acetate to propionate ratio (A/P), and ammonia nitrogen (NH3-N)were higher (p < 0.05) in PT ewes than those in CON ewes. 16S rRNA analysis showed the differences of ß-diversity were observed in rumen microbiota between CON and PT ewes. At the phylum level, the relative abundance of Bacteroidota and Proteobacteria were higher (p < 0.01), while Firmicutes was lower (p < 0.01) in PT ewes. At the genus level, the relative Prevotella, Butyrivibrio, Ruminococcus, Lachnospiraceae_AC2044_group, Lachnospiraceae_XPB1014_group, Lachnospiraceae_ND3007_group, and Oribacterium were lower (p < 0.01) in PT ewes. Meanwhile, the relative abundance of Oribacterium, Butyrivibrio, Ruminococcus, and Lachnospiraceae_AC2044_group were positively correlated (p < 0.01) with Glu, INS, acetate, propionate, and butyrate, and negatively correlated (p < 0.01) with BHBA, P, GC, AST, and A/P. Discussion: In conclusion, the decrease of Oribacterium, Butyrivibrio, Ruminococcus, and Lachnospiraceae_AC2044_group in the rumen of PT ewes reduced the concentrations of volatile fatty acids (acetate, propionate, and butyrate) and serum Glu, and increased BHBA concentration, indicating that the differences in rumen bacteria genera were related to pregnancy toxemia of ewes. [ABSTRACT FROM AUTHOR]

Bone is a dynamic tissue that is constantly remodeled throughout adult life. Recently, it has been shown that bone turnover decreases shortly after food consumption. This process has been linked to the fermentation of non-digestible food ingredients such as inulin by gut microbes, which results in the production of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate. SCFAs exert various metabolic functions, which in part can be explained by activation of G protein-coupled receptors (Gpr) 41 and 43. However, the potential relevance of a SCFA-Gpr41/43 signaling axis for bone metabolism has not been established. The aim of our study is to investigate the role of Gpr41/43 in bone metabolism and osteogenic differentiation of mesenchymal stem cells. For this purpose, we analyzed the skeletal phenotype of wild type controls (WT) and Gpr41/43 double knockout (Gpr41/43 dKO) mice fed either a chow or an inulin-enriched diet. In addition, we isolated bone marrow derived mesenchymal stem cells from WT and Gpr41/43 dKO mice and differentiated them into osteoblasts in the absence or presence of acetate. MicroCT scanning of femoral bones of Gpr41/43 dKO mice revealed a significant increase of trabecular bone volume and trabecular compared to WT controls. Treatment of WT bone marrow-derived osteoblasts with acetate resulted in decreased mineralization and substantial downregulation of bone formation markers such as Phex, Ptgs2 and Col1a1. Notably, this effect was strongly attenuated in differentiated osteoblasts lacking Gpr41/43. Inversely, acetate supplementation resulted in higher levels of adipocyte marker genes including Pparg, Lpl and Adipoq in bone marrow-derived cells from WT mice, an effect blunted in differentiated cells isolated from Gpr41/43 dKO mice. Overall, these data indicate that acetate regulates bone architecture via SCFA-Gpr41/43 signaling by modulating the osteogenic versus adipogenic differentiation of mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

Simple Summary: This study evaluated the influence of four active dry yeasts (ADYs) on nutrient digestibility and rumen fermentation in lambs through in vitro and in vivo experiments. Notably, Vistacell (Vis) and Procreatin7 (Pro) showed enhanced total gas production and pH levels in vitro. Vis improved in vivo propionate molar proportion, NDF digestibility, and total VFA concentration, suggesting it is the most suitable for lamb growth. However, the study highlighted discrepancies between in vitro and in vivo outcomes, cautioning against directly translating batch culture results to live animal effects. This study assessed the impact of active dry yeast (ADY) on nutrient digestibility and rumen fermentation, using both in vitro and in vivo experiments with lambs. In vitro, ADYs were incubated with rumen fluid and a substrate mixture to assess gas production, pH, volatile fatty acid (VFA) profiles, and lactate concentration. In vivo, Hu lambs were randomly assigned to five dietary treatments: a control group and four groups receiving one of two dosages of either Vistacell or Procreatin7. Growth performance, nutrient digestibility, rumen fermentation parameters, and bacterial community composition were measured. Pro enhanced the propionate molar proportion while it decreased the n-butyrate molar proportion. Vis reduced the lactate concentration in vitro. In the in vivo experiment, Vis increased the propionate molar proportion and the Succinivibrionaceae_UCG-001 abundance while it decreased the n-butyrate molar proportion and the Lachnospiraceae_ND3007 abundance. Additionally, Vis showed a greater impact on improving the NDF digestibility and total VFA concentration in vivo compared to Pro. Overall, the effects of ADYs on rumen fermentation were found to vary depending on the specific ADY used, with Vis being the most suitable for lamb growth. It was observed that Vis promoted propionate fermentation and Succinivibrionaceae_UCG-001 abundance at the expense of reduced n-butyrate fermentation and Lachnospiraceae_ND3007 abundance. Importantly, differences were noted between the outcomes of the in vitro and in vivo experiments concerning the effects of ADYs on rumen fermentation, highlighting the need for caution when generalizing batch culture results to the in vivo effects of ADYs. [ABSTRACT FROM AUTHOR]

Simple Summary: In pasture-based dairy systems, supplementing the diet is crucial during periods when pasture availability is low. Field peas, which can be locally produced, offer relatively high concentrations of crude protein, along with significant energy content in the form of starch, all at a lower price. These qualities make field peas a sustainable alternative to traditional protein and energy sources such as soybean meal and corn grain. This study explored the impact of substituting traditional feeds with field peas in the concentrates of grazing dairy cows. Our findings indicate that using field peas maintains milk production and composition (protein and fat) without affecting intake or ruminal and blood parameters. This suggests that field peas are a viable alternative for feeding dairy cows, supporting consistent production under grazing conditions. This study assessed the effects of replacing soybean meal (SBM) and corn grain with field peas in the concentrate of grazing dairy cows on milk production, intake, ruminal fermentation, and blood indicators. Twelve multiparous lactating Holstein-Friesian cows were utilized in a replicated 3 × 3 Latin square design, comprising three periods and three treatments: (1) Pea-0 (Control diet): 6 kg dry matter (DM) of fresh pasture, 7.2 kg DM of grass silage, and 7 kg DM of a concentrate containing 0% pea; (2) Pea-30: Control diet with the concentrate composed of 30% pea; (3) Pea-60: Control diet with the concentrate composed of 60% pea. The effect of treatments on productive and metabolic parameters was evaluated using linear-mixed models. Pasture and total DM intake, milk production, and composition were unaffected by treatments. Despite the concentrates being isonitrogenous and isoenergetic, crude protein (CP) intake was slightly higher in Pea-30 and significantly higher in Pea-60 due to higher pasture CP content in the pasture grazed by these groups, leading to higher milk urea content, though within recommended ranges. Blood parameters showed no significant changes, except for plasma β-hydroxybutyrate, which was lowest in the Pea-60 treatment; however, all values were within ranges not indicative of subclinical ketosis. Ruminal fermentation parameters were similar across treatments. These findings support the use of field peas as a viable alternative to replace SBM and corn grain in concentrates, enabling similar milk production and composition in grazing dairy cows. [ABSTRACT FROM AUTHOR]

Simple Summary: Weaning stress affects the health of calves, inhibiting growth and disrupting gastrointestinal function. Benzoic acid (BA) is known for promoting growth and intestinal health. This study aims to investigate the effects of BA on the growth performance, rumen fermentation, and rumen microbiota of weaned Holstein dairy calves. Thirty-two Holstein dairy calves (60 days of age) were randomly divided into four groups (n = 8) supplemented with 0%, 0.25%, 0.50%, and 0.75% BA to the basal diet (dry matter basis) for 42 days, respectively. The results showed that supplementation with 0.50% BA promoted growth performance by increasing feed intake and average daily gain and reducing feed-to-gain ratio, improved rumen fermentation parameters, and increased the relative abundance of probiotics in the rumen. This suggests that 0.50% BA supplementation might be an effective method for the efficient breeding of weaned calves. Supplementation with benzoic acid (BA) in animal feed can reduce feeds' acid-binding capacity, inhibit pathogenic bacterial growth, enhance nutrient digestion, and increase intestinal enzyme activities. This study aimed to investigate the effects of different doses of BA on the growth performance, rumen fermentation, and rumen microbiota of weaned Holstein dairy calves. Thirty-two Holstein calves at 60 days of age were randomly assigned into four groups (n = 8): a control group (fed with a basal diet without BA supplementation; CON group) and groups that were supplemented with 0.25% (LBA group), 0.50% (MBA group), and 0.75% (HBA group) BA to the basal diet (dry matter basis), respectively. The experiment lasted for 42 days, starting at 60 days of age and ending at 102 days of age, with weaning occurring at 67 days of age. Supplementation with BA linearly increased the average daily gain of the weaned dairy calves, which was significantly higher in the LBA, MBA, and HBA groups than that in the CON group. The average daily feed intake was quadratically increased with increasing BA supplementation, peaking in the MBA group. Supplementation with BA linearly decreased the feed-to-gain (F/G) ratio, but did not affect rumen fermentation parameters, except for the molar proportion of butyrate and iso-butyrate, which were linearly increased with the dose of BA supplementation. Compared with the CON group, the molar proportions of iso-butyrate in the LBA, MBA, and HBA groups and that of butyrate in the HBA group were significantly higher than those in the CON group. Supplementation with BA had no significant effect on the alpha and beta diversity of the rumen microbiota, but significantly increased the relative abundances of beneficial bacteria, such as Bifidobacterium, and reduced those of the harmful bacteria, such as unclassified_o__Gastranaerophilales and Oscillospiraceae_UCG-002, in the rumen. Functional prediction analysis using the MetaCyc database revealed significant variations in the pathways associated with glycolysis across groups, including the GLYCOLYSIS-TCA-GLYOX-BYPASS, GLYCOL-GLYOXDEG-PWY, and P105-PWY pathways. In conclusion, BA supplementation improved the composition and function of rumen microbiota, elevated the production of butyrate and iso-butyrate, and increased the growth performance of weaned Holstein dairy calves. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the effect of artificially rearing Holstein Friesian bull calves with either forage- (FS) or concentrate-based starter diets on rumen fermentation and blood metabolite profiles to 4.5 mo, residual feed intake (RFI) at 10 mo, lifetime growth, and carcass traits and meat quality at slaughter in a pastoral grazing system. Holstein-Friesian bull calves were allocated to FS or PS diets (n = 20/group). The FS calves grew slower than PS calves following MR weaning up to 100 kg BW but tended to grow faster up to 18 wks while grazing pasture with no difference in BW observed thereafter. Rumen fermentation profiles differed at wk 7 and 12 but not thereafter. Residual feed intake (RFI), age and weight at slaughter and meat yield/quality were similar between groups. These results highlight that artificially reared Friesian bulls fed a FS compared to PS starter diet take slightly longer to reach 100 kg BW but are better prepared for weaning onto pasture, with no long-term differences in RFI, growth and beef production/quality. This study highlights the opportunity for beef producers to utilise a whole of life grain-free alternative feeding system to meet specific market requirements. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The effects of high (2.5% of DM) versus normal dietary sodium chloride (NaCl) intake on renal urea-N kinetics and urea-N metabolism were investigated in 9 rumen-cannulated and multicatheterized lactating dairy cows in a crossover design with 21-d periods. It was hypothesized that urinary urea-N excretion would be greater, and BUN concentration lower in response to greater diuresis induced by high NaCl intake. Also, urea-N transport across ruminal and portal-drained viscera (PDV) tissues was hypothesized to be affected by dietary sodium intake. A second experiment was conducted using 8 lactating cows in a crossover design with 14-d periods to test high NaCl (2.5% of DM) versus high KCl (3.2% of DM) intake on milk yield and MUN concentrations. Experiment 1 showed that despite greater diuresis, high NaCl intake had no effect on urinary urea-N excretion or BUN concentration. The high NaCl intake did not affect rumen ammonia concentrations, total rumen VFA concentrations, ruminal venous − arterial concentration differences for ammonia, or ammonia absorption indicating that high NaCl did not adversely affect ruminal fermentation and microbial protein synthesis. High NaCl intake did not affect the total amount of urea-N transport from blood to gut, but ruminal venous − arterial concentration differences for urea-N were lower with high NaCl and ruminal extraction of arterial urea-N was numerically smaller, indicating that the ruminal epithelial urea-N transport was lower with high NaCl. Energy-corrected milk yield was greater with high NaCl (3.2 ± 1.5 kg/d); however, MUN concentrations were not affected by treatment. In experiment 2, ECM was greater with NaCl (1.4 ± 0.31 kg/d) compared with KCl (30.2 and 28.8 ± 0.91 kg ECM/d, respectively). Milk urea-N concentration was lower with KCl, suggesting a urea-N lowering effect in milk not evident with high NaCl intake. In conclusion, the present data show that dietary Na intake of 12 to 13 g/kg DM was followed by greater diuresis but did not affect urea-N excretion or BUN concentration. High NaCl intake did not affect the total amount of urea-N transfer across PDV tissues. Energy-corrected milk yield was greater with high NaCl compared with both control and feeding KCl; however, with KCl, MUN decreased. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The objective of this study was to evaluate the effects of amino resin-treated soybean meal (SBM) on ruminal fermentation, nutrient digestion, and N partitioning. The treatments were (1) untreated solvent-extracted SBM, (2) amino resin-treated SBM (AR-SBM), and (3) heat-treated SBM (HT-SBM). The experimental design was arranged as a replicated 3 × 3 Latin square with 6 fermentors in a dual-flow continuous culture system. Treatments were randomly assigned to fermentors within a Latin square for each period. Each fermentor was fed 106 g/d of diet DM equally distributed in 2 feeding times daily at 0800 and 1800 h. Diets were formulated to contain 16% CP, 30% NDF, and 30% starch across treatments. The experiment consisted of 3 experimental periods, each lasting for 10 d. The first 7 d of each period were considered adaptation, and the last 3 d were used for sampling and data collection. On d 8 and 9, samples were collected for analysis of diurnal variation in concentrations of NH 3 -N, pH, and VFA during the first 8 h after feeding. On d 8, 9, and 10, samples were collected from the liquid and solid effluents accumulated over 24 h for analysis of daily averages of NH 3 -N and VFA pools, and true ruminal digestibility estimates. Data were analyzed using the MIXED procedure of SAS, and significance was declared when P ≤ 0.05. The model included the fixed effect of treatment and random effects of square, period, and fermentor within square, whereas time and interaction treatment × time were included for analyses of diurnal variation, with time as repeated measures. Compared with SBM, the cultured ruminal contents of AR-SBM and HT-SBM had lower NH 3 -N concentrations, indicating lower microbial fermentation of protein. Molar proportions of isovalerate and isobutyrate were greater in SBM than AR-SBM and HT-SBM, with greater molar proportion of isobutyrate for SBM, particularly during the first 2 h after feeding. The flow of NH 3 -N was greater for SBM compared with AR-SBM and HT-SBM, whereas NAN flow, bacterial N flow, and N efficiency were greater for AR-SBM and HT-SBM compared with SBM. Our results indicate that both the amino resin and heat treatments of SBM allow for similar decreases in microbial degradation of CP without limiting microbial protein synthesis in diets with 16% CP. Amino resin treatment may be effective in reducing microbial fermentation of protein in the rumen without adverse effects on digestibility or fermentation parameters as compared with SBM. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The purpose of this experiment was to determine if nicotinic acid (NA) effects on dairy cows and rumen microbial characteristics are forage-type dependent (corn silage, CS; grass silage, GS). Four late-lactation (DIM = 225 ± 12 d) Holstein cows were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. The main effects were a CS (66.10% CS) based diet or a GS (79.59%) based diet with or without 12 g/d NA. Each experimental period lasted for 28 d. Milk production and milk components, blood metabolites, apparent total-tract nutrient digestibilities, minutes rumen pH were below 5.8 as an indicator of ruminal acidosis, and body temperature changes were analyzed as indicators of heat stress. Nicotinic acid supplementation did not improve apparent total-tract nutrient digestibility. Feeding a GS-based diet improved NDF and hemicellulose digestibility. Feeding a CS-based diet increased the apparent total-tract digestibility of fat, and minutes rumen pH below 5.8 for a greater proportion of the time. The CS-based diet also improved milk yield, milk fat and protein yields, and ECM yield; however, somatic cell count and BHB were also increased. Supplementing NA tended to decrease nonesterified fatty acids, especially when combined with GS where DMI was low. There was a trend for the total protozoa population to increase when GS and NA were fed but decreased when CS and NA were fed. Nicotinic acid tended to decrease rumen protozoal populations of Dasytricha , but increased populations of Ophryoscolex and Diplodiniinae with GS diets and decreased with CS diets. Entodiniinae were increased with CS but NA had no effect. Body temperature was increased when a CS-based diet was fed when compared with a GS-based diet. More research is needed to determine how NA can affect rumen microbial protein synthesis and what kind of diets will provide the optimum effect. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the impact of Aspergillus niger lysing polysaccharide monooxygenase (AnLPMO) on in vitro rumen microbial fermentation of rice straw. Methods: AnLPMO was heterologously expressed in Escherichia coli. Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy analyzed the surface structure of rice straw after AnLPMO treatment. Two in vitro experiments, coupled with 16S highthroughput sequencing and quantitative real–time polymerase chain reaction techniques, assessed the influence of AnLPMO on rumen microbial fermentation of rice straw. Results: AnLPMO exhibited peak activity at 40°C and pH 6.5, with a preference for rice straw xylan hydrolysis, followed by Avicel. AnLPMO application led to the fractional removal of cellulose and hemicelluloses and a notable reduction in the levels of carbon elements and C–C groups present on the surface of rice straw. Compared to the control (no AnLPMO), supplementing AnLPMO at 1.1 to 2.0 U significantly enhanced in vitro digestibility of dry matter (IVDMD, p<0.01), total gas production (p<0.01), and concentrations of total volatile fatty acids (VFA, p<0.01), acetate (p<0.01), and ammonia-N (p<0.01). Particularly, the 1.4 U AnLPMO group showed a 14.8% increase in IVDMD. In the second experiment, compared to deactivated AnLPMO (1.4 U), supplementing bioactive AnLPMO at 1.4 U increased IVDMD (p = 0.01), total gas production (p = 0.04), and concentrations of total VFA (p<0.01), propionate (p<0.01), and ammonia-N (p<0.01), with a limited 9.6% increase in IVDMD. Supplementing AnLPMO stimulated the growth of ruminal bacterial taxa facilitating fiber degradation, including Proteobacteria, Spirochaetes, Succinivibrio, Rikenellaceae_RC9_ Gut_Group, Prevotelaceae_UCG-003, Desulfovibrio, Fibrobacter succinogenes, Ruminococcus albus, R. flavefaciens, Prevotella bryantii, P. ruminicola, and Treponema bryantii. Conclusion: These findings highlight AnLPMO's potential as a feed additive for improving rice straw utilization in ruminant production. [ABSTRACT FROM AUTHOR]

Objective: This experiment aimed to evaluate the effects of replacing concentrates with cassava root-top silage (CARTOS) on feed intake, digestibility, rumen fermentation, blood parameters, and growth performance of beef cattle. Methods: Twenty crossbred bulls with a body weight (BW) of 226±56 kg were randomly assigned to one of five treatments for 90 d in a randomized complete block design having four blocks based on BW. The concentrates were replaced by CARTOS at levels of 0%, 25%, 50%, 75%, and 100% dry matter (DM). Animals were fed dietary treatments at 1.8% BW, with rice straw offered ad libitum. Results: The DM and crude protein (CP) intake were decreased (p<0.01, p = 0.04) when the diet’s CARTOS level was increased. The digestibility of DM, OM, and CP were not different among treatments, while fiber digestibility was increased with the inclusion of CARTOS (p = 0.03). The addition of CARTOS to replace concentrates did not change ruminal pH or volatile fatty acid proportions except for acetic acid, which increased with the addition of CARTOS (p = 0.03). The ruminal ammonia-nitrogen (NH3-N) was decreased (p<0.01) with increasing levels of CARTOS. The blood glucose and blood urea nitrogen decreased (p = 0.01) with the addition of CARTOS at 100%, whereas total protein and hematological parameters did not change with increasing levels of CARTOS. The use of CARTOS to substitute concentrates at 75% and 100% decreased average daily gain (ADG) and gain to feed ratio (G:F) (p<0.01); therefore, the addition of CARTOS up to 50% maintained ADG and G:F in beef cattle. Conclusion: CARTOS can replace concentrates up to 50% in beef cattle diets without adversely affecting feed intake, nutrient digestibility, rumen fermentation characteristics, blood parameters, or growth performance of beef cattle. [ABSTRACT FROM AUTHOR]

The increase in global temperatures over the past few decades due to greenhouse gas emissions has raised concerns and necessitated further research in climate change mitigation and adaptation. Methane is a prominent greenhouse gas that significantly contributes to climate change, with a substantial amount generated through fermentation processes occurring in the rumen of ruminant animals. The potential of plant secondary metabolites, especially those derived from tannin-rich plants, warrants investigation to modify rumen fermentation and mitigate methane emissions in livestock diets. The objective of this study was to assess the impact of extracts obtained from green and black tea waste on rumen fermentation dynamics and gas (methane) production, utilizing in vitro methods. For this purpose, rumen fluid was collected from two fistulated sheep and subjected to three treatments: (1) a basal diet (control), (2) a basal diet + green tea waste extract (5% of dry matter), (3) a basal diet + black tea waste extract (5% of dry matter). The study assessed the effects of incorporating extracts from green and black tea waste on various parameters, including digestibility, protozoa population, ammonia nitrogen levels, volatile fatty acids, and methane gas production following a 24-h incubation period. Statistical analysis of the data was conducted using SAS software within a completely randomized design framework. The findings indicated that the addition of green and black tea waste extracts significantly decreased methane gas production (p < 0.05), protozoa count (p < 0.05), and ammonia nitrogen concentrations in rumen fluid (p < 0.05) when compared to the control group. The addition of green and black tea waste extracts has significantly altered the concentration of VFAs in rumen fluid (p < 0.05). Specifically, the addition of green tea waste extract has led to a highly significant reduction in acetic acid, (p < 0.01) and the addition of both extracts has resulted in a significant increase in propionic acid (p < 0.05). Consequently, the results suggest that the inclusion of green and black tea waste extracts in livestock diets may effectively mitigate methane emissions in the rumen, thereby reducing feed costs and reducing environmental pollution. [ABSTRACT FROM AUTHOR]

Traditionally, Tibetan sheep only graze pastures without any supplementary feed. However, in recent years, feedlots are being used for fattening Tibetan sheep. The present study compared the growth rates, blood parameters, rumen fermentation, and bacterial communities in Tibetan sheep fattened by pasture grazing (PG) versus those fattened by stall feeding (SF). Twenty 18-month-old Tibetan sheep wethers (42.6 ± 2.11 kg) were divided randomly into PG (n = 10) and SF (n = 10) groups. The PG sheep grazed the grasslands without any supplementary feed, while the SF sheep were offered a commercial total mixed ration (TMR) at a crude protein content of 16.2% DM and an ME of 10.59 MJ/kg. The sheep were on their treatments for 70 days, which included 10 days for adaptation and 60 days for measurements. The average daily gain, white blood cell and lymphocyte counts were greater (p < 0.05), while the platelet count was lower (p < 0.05) in the SF group than in the PG group. The serum glutathione peroxidase activity, and concentrations of total proteins and albumin were greater (p < 0.05), while glucose was lower (p < 0.01) in the PG group compared to the SF group. The concentrations of ruminal ammonia–N and total volatile fatty acids (VFAs) were greater (p < 0.05), while the pH was lower (p < 0.05) in the SF group compared to the PG group. The molar proportion of acetate and the ratio of acetate to propionate were greater (p < 0.01) in the PG sheep than in the SF sheep, but the molar proportion of propionate and iso-VFAs did not differ (p > 0.05) between the groups. Based on the PCoA, the ruminal bacterial communities were distinct between groups, and the alpha diversity was greater (p < 0.001) in the PG sheep than in the SF sheep. The dominant phyla of the rumen bacteria were Firmicutes and Bacteroidetes, while the Firmicutes to Bacteroidetes ratio was greater (p < 0.001) in the SF group than in the PG group. At the genus level, the relative abundance of Ruminococcus was greater (p < 0.05) in the SF group, while the abundances of Prevotella, the Rikenellaceae_RC9_gut_group, Butyrivibrio, and unclassified_f_Lachnospiraceae were greater (p < 0.05) in the PG group. It was concluded that the Tibetan sheep adopted a short-term intensive fattening strategy when stall fed which altered the rumen bacterial community and blood parameters, enhanced rumen fermentation, and, ultimately, improved their average daily gain. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of nano-encapsulation of four essential amino acids (AA), threonine, methionine, tryptophan, and lysine on in vitro ruminal total gas, methane, carbon monoxide, and hydrogen sulfide production as well as the rumen fermentation profile in cattle. The highest (P < 0.001) rate and asymptotic gas production after 48 h of incubation was observed in the diets that had threonine, followed by lysine, methionine, and tryptophan. Asymptotic methane gas production decreased in the following order: threonine > lysine > tryptophan > methionine (P < 0.0001) and the rate of production per hour followed the same trend (P = 0.0259). CH4 parameters showed that in 4 h, 24 h, and 48 h of incubation the lowest methane production was obtained in the diet with methionine (P < 0.05) and the highest one in diet supplemented with threonine. Methane fractions showed that methionine-containing diets resulted in more (P < 0.05) metabolizable energy versus methane, followed by tryptophan-containing, and then lysine-containing diets. Methionine-fortified diets seem to be the most eco-friendly among those studied regarding methane output. However, based on methane, CO, and H2S output as well as the rumen fermentation profile nano-encapsulated lysine is recommended for use in ruminant nutrition. [ABSTRACT FROM AUTHOR]

Fat supplements are well known for their multiple beneficial effects on ruminant health, reproduction and productivity, and as a source for certain bioactive compounds in ruminant products. On the other hand, numerous phytochemicals have demonstrated the potential to improve rumen fermentation through modifying the volatile fatty acid (VFA) pattern to favour those with greater energy efficiency, boosting microbial protein synthesis, and decreasing methane emission and ruminal ammonia concentration. Savory is an aromatic plant rich in various phytochemicals (mainly carvacrol and flavonoids) that can alter ruminal metabolism of dietary fatty acids, potentially increasing the production of some bioactive compounds such as conjugated linoleic acids (CLAs). This study aimed to investigate combined effects of oil type (fish oil (FO) versus soybean oil (SO)) and the inclusion of savory (Satureja khuzistanica) plant (SP) in the diet on total tract digestibility of nutrients, rumen fermentation, milk yield and milk fatty acid profile in dairy cattle. Eight multiparous lactating Holstein cows were used in a replicated 4 × 4 Latin square design experiment with four diets and four 21-d periods. During each experimental period consisted of 14 days of adaptation and a 7-day sampling period, cows were randomly assigned to one of the four dietary treatments: the diet supplemented with 2% (DM basis) fish oil (FOD) or soybean oil (SOD), the FOD or SOD plus 370 g DM/d/head SP (FODs, SODs, respectively). The experimental diets were arranged in a 2 × 2 factorial design, with the fat sources as the first and SP as the second factor. The FO-supplemented diets had lower dry matter intake (DMI) and higher total tract digestibility than SO-supplemented diets (P < 0.05), and including SP in the diet improved total tract digestibility of dry matter (DM), organic matter (OM), ether extract (EE), and non-fibrous carbohydrates (NFC) (P < 0.05) without negatively affecting DMI. Rumen pH was lower with SO than with FO diets (P < 0.01) and increased with SP inclusion in the diet (P < 0.05). Total protozoa count and ruminal ammonia concentration decreased, and the branched-chain VFA (BCVFA) proportion increased with SP inclusion in the diet (P < 0.05). Milk production, as well as the concentration and yield of milk components (except lactose concentration) were higher with SO than with FO diets (P < 0.05), but these variables remained unaffected by SP. The milk concentrations of both non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB) were lower with SO compared to FO diets, and these variables were reduced by SP (P < 0.01). The proportions of both mono- and polyunsaturated FA (MUFA and PUFA, respectively) in milk were higher with FO than with SO diets (P < 0.01), and their proportions increased by SP at the expense of saturated FA (SFA) (P < 0.01). Including SP in the diet increased the proportions of all the milk n-3 FA (C18:3c, C20:5, and C22:6) by 21%, 40%, and 97%, respectively, and those of conjugated linoleic acids (C18:2 (c9,t11-CLA) and C18:2 (t10,c12-CLA)) by 23% and 62%, respectively. There was no interaction between oil type and SP for the assessed variables. Fish oil, despite reducing milk production and milk components, was more effective than soybean oil in enriching milk with healthy FA. These findings also show promise for SP as a feed additive with the potential to improve total tract digestibility, rumen fermentation and milk FA composition. [ABSTRACT FROM AUTHOR]

Ruminant livestock are major contributors to anthropogenic methane emissions in the United States and worldwide. Enteric methane is generated by methanogenic archaea residing in ruminant digestive tracts. Information on when methanogens colonize the gut and when they begin to interact with bacteria during the early phases of the ruminant life cycle is less explored. The objectives of this study were (i) to investigate the composition of the methanogenic archaeal community at birth and through the weaning transition and (ii) to determine if and when the methanogenic archaea begin to interact with bacteria in the lower gut of neonatal dairy calves. Ten female Holstein calves (approximately 45kg birth weight) were enrolled in the study. Fecal samples were collected every two weeks (Wk 2, 4, 6, 8, 10, and 12) between birth and weaning and analyzed for methanogenic archaeal diversity via 16S rRNA amplicon sequencing and quantitative real-time PCR (RT-qPCR). Estimates of alpha diversity (Observed species, and Shannon diversity index) and beta diversity (weighted and unweighted UniFrac distances) showed significant differences (P < 0.05) between archaeal communities across timepoints. Both 16S rRNA amplicon sequencing and RT-qPCR analyses revealed Methanobrevibacter was the most prevalent genus at Wk2, Wk4, and Wk6, whereas Methanosphaera gradually increased with time and was most abundant at Wk10 and Wk12. Correlation analysis revealed that Methanobrevibacter and Methanosphaera were inversely correlated with each other and formed distinct cohorts with specific bacterial lineages similar to those reported in the mature rumen, thus revealing that these associations are established during the preweaning period. Therefore, the preweaning period presents a window of opportunity to interfere with early-life methanogenic colonization with the ultimate goal of reducing enteric methane emissions without perturbing ruminal function later in the life of dairy cattle. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Flaxseed lignans, types of polyphenolic compounds, primarily consist of secoisolariciresinol diglucoside (SDG). Natural plant extracts are becoming increasingly important as feed for ruminant animals. An underutilized plant bioactive component, SDG shows promising benefits for young ruminant production. The objective of this study was to assess the impact of SDG on rumen fermentation using an in vitro rumen simulation technology. Additionally, we tested the effects of SDG (0.20 g kg−1 body weight) on rumen development and production performance of lambs in a production setting.The in vitro addition of 100 mg L−1 SDG demonstrated significant regulatory effects, with a notable decrease in the acetate/propionate ratio (P < 0.05). Feeding trials revealed that SDG significantly increased average daily feed intake and average daily weight gain (P < 0.05), and reduced the acetate/propionate ratio (P < 0.05). This led to a significant increase in the relative abundance of Eubacterium ruminantium (P = 0.038) and Butyrivibrio (P = 0.002). Furthermore, it promoted rumen development and upregulated the relative expression of mRNA of Cyclin E1 and CDK2 in rumen epithelial cells (P < 0.05).The SDG extract optimizes the composition of rumen microbiota and the development of rumen epithelial cells, promoting the growth of pre‐weaning lambs. The SDG additive exhibits potential as a novel growth promoter for ruminant animals, offering a promising solution for sustainable livestock production. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Feed costs account for a high proportion of the variable cost of beef production, ultimately impacting overall profitability. Thus, improving feed efficiency of beef cattle, by way of determining the underlying genomic control and selecting for feed efficient cattle provides a method through which feed input costs may be reduced whilst also contributing to the environmental sustainability of beef production. The rumen microbiome dictates the feed degradation capacity and consequent nutrient supply in ruminants, thus potentially impacted by feed efficiency phenotype. Equally, liver tissue has been shown to be responsive to feed efficiency phenotype as well as dietary intake. However, although both the rumen microbiome and liver transcriptome have been shown to be impacted by host feed efficiency phenotype, knowledge of the interaction between the rumen microbiome and other peripheral tissues within the body, including the liver is lacking. Thus, the objective of this study was to compare two contrasting breed types (Charolais and Holstein-Friesian) divergent for residual feed intake (RFI) over contrasting dietary phases (zero-grazed grass and high-concentrate), based on gene co-expression network analysis of liver transcriptome data and microbe co-abundance network of rumen microbiome data. Traits including RFI, dry matter intake (DMI) and growth rate (ADG), as well as rumen concentrations of volatile fatty acids were also included within the network analysis. Results: Overall, DMI had the greatest number of connections followed by RFI, with ADG displaying the fewest number of significant connections. Hepatic genes related to lipid metabolism were correlated to both RFI and DMI phenotypes, whilst genes related to immune response were correlated to DMI. Despite the known relationship between RFI and DMI, the same microbes were not directly connected to these phenotypes, the Succiniclasticum genus was however, negatively connected to both RFI and ADG. Additionally, a stepwise regression analysis revealed significant roles for both Succiniclasticum genus and Roseburia.faecis sp. in predicting RFI, DMI and ADG. Conclusions: Results from this study highlight the interactive relationships between rumen microbiome and hepatic transcriptome data of cattle divergent for RFI, whilst also increasing our understanding of the underlying biology of both DMI and ADG in beef cattle. [ABSTRACT FROM AUTHOR]

Simple Summary: This study was conducted to explore the optimal level of Rheum palmatum root (RP) for the mitigation of enteric methane and demonstrate the effects on methane production and rumen fermentation characteristics in cattle fed with RP. In the in vitro trial, 3% of RP addition most effectively reduced methane production, which determined the feeding level for the test subjects in the in vivo trial. In the in vivo trial, RP addition did not affect methane emissions in the steers, likely due to the adaptation of ruminal microorganisms to the RP addition. This study investigated the impact of Rheum palmatum root (RP) for reducing methane and its impact on rumen fermentation and blood metabolites in cattle. Rumen fluid was collected from three cannulated steers (736 ± 15 kg) and mixed with buffer (1:3 ratio) for the in vitro trial. Treatments were divided into control and RP supplement groups (1%, 3%, and 5% of substrates), with each sample incubated at 39 °C for 24 and 48 hours. Methane was measured after incubation, showing a dose-dependent linear decrease after 48 hours. Quadratic changes were observed in total volatile fatty acids, acetate, and butyrate. Additionally, in vitro dry matter digestibility decreased linearly with RP inclusion. In vivo trials involved four Korean steers in a 2 × 2 crossover design over 3 weeks, with treatments including a control group and a group with 3% RP addition. Dry matter intake (DMI) tended to decrease in the RP group compared to the control. Methane emissions (g/kg DMI) were not affected by RP addition. Blood metabolites indicated higher lipase concentrations in the RP group. In conclusion, RP reduced methane production in the in vitro trial but had no effect in the in vivo trial, likely due to adaptation of ruminal bacteria to RP. [ABSTRACT FROM AUTHOR]

Introduction: Postpartum period of dairy cattle is an important phase of their life mainly associated with the changes in physiology, rumen function, and energy metabolism. Studies have shown that gut microbial composition undergoes drastic changes during the postpartum period. However, little is known about the temporal variations in digestive tract microbiota in postpartum Tibetan cattle. The aim of this study was to investigate the temporal variations in blood metabolites, ruminal fermentation, and microbial community of oral, rumen, and gut in lactating Tibetan cattle during postpartum. Methods: We collected blood, saliva, rumen fluid, and fecal samples from lactating Tibetan cattle during 1st week (1 W), the 2nd week (2 W), the 1st month (1 M), and the 2nd month (2 M) of the postpartum period. The microbiota of saliva, rumen fluid, and fecal samples were assessed using 16S rRNA sequencing. The rumen volatile fatty acid and blood parameters were also quantified. Results: The content of volatile fatty acids (VFAs) and blood parameters showed opposite tendency to each other and reached to stability at 2 M. Rumen microbiota showed the highest alpha diversity compared to other two sites. At phylum level, the oral cavity was dominated by Proteobacteria, while most dominant phylum in rumen and feces were Firmicutes and Bacteroidetes, respectively. The dominant genera in oral cavity were Moraxella and Bibersteinia, while genera Prevotella 1 and Ruminococcaceae UCG-005 were dominant in rumen and fecal samples, respectively. Discussion: Microbial network analysis revealed that most of the active genera in all networks belonged to phylum Firmicutes, indicating the importance of this phyla during postpartum period of lactating cattle. The functional analysis revealed distinct division of labor among three gastrointestinal sites associated with defense, fatty acid synthesis, and maintaining health of host. All in all, our findings provide insights into the metabolic and microbial changes of lactating Tibetan cattle and help to the improvement of the management strategies [ABSTRACT FROM AUTHOR]

Background and Aim: Rice straw, a widely available agricultural byproduct globally, has significant potential as a basal diet for livestock. The major challenge lies in obtaining high-protein foliage that can be easily extracted using natural water rather than chemical solvents. This study aimed to assess the ability of distilled water to extract protein concentrate from Indigofera leaves (Indigofera zollingeriana Miq.) and to evaluate its effectiveness in enhancing rumen feed fermentation and digestibility in low-quality rice straw basal diets. Materials and Methods: The study was conducted in two experimental series. Experiment 1 was designed to explore the ability of distilled water to extract protein concentrate from fresh and dry Indigofera leaves by comparing it with the 0.1 N NaOH standard solvent. Experiment 2 focused on the in vitro digestibility of protein concentrates extracted from fresh Indigofera leaves based on optimal findings from experiment 1. Five treatments consisting of 0.5% and 1.0% protein concentrate and two extractants (distilled water and 0.1 N NaOH) were used to extract protein from Indigofera leaves. These extracts were then added to rice straw-based diets. Rice straw without supplements was used as a control. The treatments were arranged using a randomized complete design with five replicates. Results: The results of experiment 1 showed that distilled water was superior to 0.1 N NaOH for extracting protein concentrate from fresh Indigofera leaves, as revealed by higher dry matter, protein yield, total amino acids (AA), and total essential AA (EAA) production. For in vitro experiment 2, supplementation with distilled water-extracted protein concentrates successfully increased rumen fermentation and digestibility in rice straw basal diets, as indicated by higher gas production, total volatile fatty acid, and microbial protein levels compared with 0.1 N NaOH. Conclusion: Findings from this study confirm that Indigofera leaf protein concentrate offers a new alternative for enhancing rumen feed fermentation and the digestibility of low-quality rice straw diets. This study implies that it is an easy, costeffective, and environmentally friendly approach, particularly beneficial for smallholders, to extract protein concentrate from fresh Indigofera leaves using distilled water and use it to enhance the quality of rice straw for ruminant feed. The limitation of this study is that the Indigofera supplement was established using in vitro digestibility under controlled laboratory conditions, which does not reflect real rumen conditions. Therefore, further studies using in vivo digestibility in ruminant animals are required to confirm the ability of the protein extracted from indigofera to enhance rumen feed fermentation in low-protein basal diets. [ABSTRACT FROM AUTHOR]

Background: A shortage of feed resources poses challenges for sustainable livestock production. Researchers are increasingly investigating alternative feeds to replace conventional ones. Cashew nut meal (CNM), a by-product of the cashew nut kernel industry, is a promising alternative feed for ruminants owing to its good nutritive value. Due to limited research on optimal inclusion levels in ruminant diet, this study aimed to evaluate the effect of incorporating varying levels of CNM as a supplement on in vitro rumen fermentation kinetics and digestibility. Methods: Seven distinct compounded feed mixtures (CFM) were formulated, with CNM progressively replacing 0 (C0), 10 (C1), 20 (C2), 30 (C3), 40 (C4), 50 (C5) and 60 (C6) per cent of the soybean meal (SBM) protein present in the control CFM. Additionally, seven experimental complete diets (T0 to T6) were prepared by blending these CFM with Super Napier (Pennisetum purpureum x Pennisetum glaucum) hay in a 40:60 ratio. These CNM based complete diets were subjected to rumen in vitro gas production (IVGP) study with cumulative gas production (GP) measured at 0, 2, 4, 6, 8, 12, 16, 24, 36, 48, 60, 72 and 96 h post-incubation. Subsequently, in vitro true dry matter digestibility (IVTDMD) and neutral detergent fiber digestibility (NDFD) of the diets were determined using a modified in vitro two-stage technique. Later, total volatile fatty acids (TVFA) were estimated using gas chromatography. Result: Analysis of chemical composition revealed that CNM contains good protein of 256.5 g/kg. The potential gas production (D) and the rate and extent of gas production (c) for diets containing CNM ranged from 54.63 to 60.24 mL and 0.036 to 0.043 h-1, respectively. IVTDMD and NDFD analysis of the seven complete diets fell within the range of 79.12 to 80.80% and 64.72 to 66.47%, respectively. The estimated TVFA for seven complete diets ranged from 17.87 to 23.65 mM. Further, the metabolisable energy (ME) of diets ranged from 7.89 to 8.08 MJ/kg DM. Importantly, no significant differences were observed in rumen fermentation kinetics parameters, IVTDMD, NDFD and TVFA among treatments (T0 to T6). CNM could be used as an alternative to SBM in compounded feed mixtures of ruminants up to 30% (w/w) without any adverse effect on rumen fermentation pattern and digestibility. [ABSTRACT FROM AUTHOR]

This study used a meta-analytic approach to evaluate the effects of dietary supplementation with seaweed on milk yield, milk composition, nutrient digestibility, ruminal fermentation, and enteric methane (CH4) emissions of dairy cows. Data used in statistical analyses were obtained from 23 peer-reviewed scientific articles. Effect size was assessed using weighted mean differences (WMD) between seaweed-supplemented and control treatments. Dietary supplementation with seaweed decreased (p < 0.05) dry matter intake, milk protein content, milk urea nitrogen, and somatic cell count. In contrast, milk fat content, milk lactose content, and milk iodine increased (p < 0.05) in response to dietary supplementation with seaweed. Dietary supplementation with seaweed did not affect (p > 0.05) nutrient digestibility, total volatile fatty acids, acetate, and propionate. Dietary supplementation with seaweeds increased (p < 0.05) ruminal pH and ruminal concentration of butyrate and valerate. In contrast, lower (p < 0.05) ruminal ammonia nitrogen concentration, acetate/propionate ratio, daily CH4 emission, CH4 yield, and CH4 intensity were observed in response to dietary supplementation with seaweeds. In conclusion, dietary supplementation with seaweed modifies milk composition, improves ruminal fermentation, and decreases enteric methane emissions without negatively affecting milk yield or feed efficiency. [ABSTRACT FROM AUTHOR]

To study the effect of hydrated sodium calcium aluminosilicate (HSCAS) in ameliorating adverse effects of aflatoxin on in vitro rumen fermentation, five treatment groups, viz., T1: control (wheat straw; 0.2 g); T2: T1+300 ppb Aflatoxin B1 (AFB1); T3: T2+0.33% HSCAS; T4: T2+0.5% HSCAS and T5: T2+ 1.0% HSCAS were prepared and incubated in vitro. The results revealed that truly degradable dry matter (TDDM), truly degradable organic matter (TDOM), gas production (GP), microbial biomass production (MBP) and partitioning factor (PF) values in aflatoxin contaminated group (T2) were lower (p<0.05) than those of other treatment groups. The TDDM, TDOM, GP, MBP and PF values in control group (T1) were higher than those of other treatment groups, i.e., T2 to T5. These parameters improved with increasing concentration of HSCAS. The total volatile fatty acids (TVFA), acetate (A), propionate (P) and butyrate (B) values in control group (T1) were higher (p<0.05) than those of other treatment groups, i.e., T2 to T5. The TVFA, A, P and B values in aflatoxin contaminated T2 group were lower (p<0.05) than those of other treatment groups. The A:P value among various dietary treatments did not vary significantly. It was concluded that aflatoxin contamination of feed (wheat straw) at 300 ppb level significantly affected the in vitro rumen fermentation in terms of reduced TDDM, TDOM, GP, MBP, PF, TVFA concentration. Inclusion of hydrated sodium calcium aluminosilicate to the aflatoxin contaminated feed partially ameliorated the adverse effects of aflatoxin on in vitro rumen fermentation parameters. [ABSTRACT FROM AUTHOR]

Simple Summary: Guanidinoacetic acid (GAA) is a natural derivative of amino acids. They are acted upon by enzymes in the liver and transformed into essential components of the energy metabolism of muscle and nervous tissue. Although the animal synthesizes creatine, the amount is less than necessary for high growth rates, according to researchers. GAA consumed by cattle reduces fat between muscle fibers and serum cholesterol. It has a mild but positive effect on the fatty acid profile of meat—i.e., it increases myristoleic, linoleic, and arachidonic acids. We also concluded that GAA consumption increases the amount of volatile fatty acids in the rumen, especially acetic, propionic, and butyric acid. We draw attention to the acetic acid related to lipid synthesis. With the increase in population, it is increasingly necessary to produce food more efficiently. This has expanded the market for additives, which are products that directly (nutritional effect) or indirectly (effect on animal health) favor productivity. Guanidinoacetic acid (GAA) is a natural precursor of creatine. It acts as an energy reserve in skeletal muscle. In addition to being a compound with more significant bioavailability, it is more thermally stable and less expensive than creatine. Therefore, this study aimed to determine whether adding GAA to the cattle diet would alter the meat's composition and fatty acid profile. We used 24 Holstein cattle males (409 ± 5.6 kg), approximately 15 months old, and separated them into four homogeneous groups, one being the control group and three groups with various dosages of GAA in the diets (3.3; 6.6, and 9.9 g/animal/day), for an experimental period of 60 days. Blood, rumen fluid, and animal weighing were performed at three points (days 1, 30, and 60), and daily feed consumption was measured. Steers fed with GAA (9.9 g/d) showed a 16.9% increase in average daily gain (ADG) compared to the control group. These same animals (T-9.9 group) fed with GAA showed a 20% increase in fed efficiency compared to the control group. Lower leukocyte, lymphocyte, and granulocyte counts and lower cholesterol levels were observed in animals that consumed 6.6 g and 9.9 g/d GAA compared to the control group. Animals from the T-6.6 and T-9.9 groups showed 30% and 27.6% reduced bacterial activity in the rumen compared to the control group, respectively. Steers from the T-6.6 and T-9.9 groups fed with GAA showed a 20% and 37% increase in short-chain fatty acids (SCFAs) compared to the control group, respectively. A higher concentration of acetic, propionic, and butyric acids in the ruminal fluid of cattle T-9.9 group was observed at day 60. The two highest doses of GAA showed lower fat levels in the meat, just as the cattle that received 9.9 g/d showed higher levels of total polyunsaturated fatty acids. Complementary data results draw attention to the dose of 9.9 g/d GAA in cattle diets, as anti-inflammatory action can be seen and combined with a higher concentration of SCFAs, consequently increases weight gain. We concluded that consuming this GAA increases the concentration of some unsaturated fatty acids (omegas) in the meat, which adds quality to the product for the consumer. [ABSTRACT FROM AUTHOR]

Simple Summary: Heat stress detrimentally affects dairy cows, resulting in economic losses during dairy production. Therefore, this study aimed to evaluate the effects of an automatic spraying method on alleviating heat stress in cows and identifying potential mechanisms. Our findings showed that the automated sprinkler cooling system treatment effectively reduced body temperatures, improved milk yield and quality, enhanced rumen fermentability, modulated rumen microbial communities, and significantly proliferated carbohydrate-degrading bacteria. Moreover, our study demonstrated that the automatic spraying cooling system had modulatory effects on rumen microbiota composition and fermentation function, and causatively ameliorated the side effects of heat stress in dairy cows. (1) Background: Heat stress detrimentally restricted economic growth in dairy production. In particular, the cooling mechanism of the spraying system effectively reduced both environmental and shell temperatures. This study was designed to investigate the underlying modulatory mechanism of an automatic cooling system in alleviating heat-stressed dairy cows. (2) Methods: A total of 1208 multiparous dairy cows was randomly allocated into six barns, three of which were equipped with automatic sprinklers (SPs), while the other three were considered the controls (CONs). Each barn was considered a replicate. (3) Results: Body temperatures and milk somatic cell counts significantly decreased, while DMI, milk yield, and milk fat content significantly increased under SP treatment. Rumen fermentability was enhanced, embodied by the increased levels of total VFA, acetate, propionate, and butyrate after SP treatment. The rumen microbiota results showed the relative abundances of fiber-degrading bacteria, including the Fibrobacters, Saccharofermentans, Lachnospira, Pseudobutyrivibrio, Selenomonas, and Succinivibrio, which significantly increased after receiving the SP treatment. (4) Conclusions: This study demonstrated that SP effectively alleviated heat stress and improved production performances and milk quality through modulating the rumen microbiota composition and fermentation function of dairy cows. [ABSTRACT FROM AUTHOR]

Simple Summary: The methane (CH4) production in ruminants not only decreases the efficiency of dietary energy utilization but also contributes to the greenhouse effect. The rumen epithelium serves as the primary site for the absorption of essential nutrients. This study systematically investigated the effects of tea polyphenols on methane production and the rumen epithelial cell transport capability in cattle using both in vitro and animal experiments, employing multi-omics techniques. In vitro results demonstrated that, compared to the control group, tea polyphenols significantly reduced CH4 production and the acetate/propionate ratio. Tea polyphenols reduce the generation of CH4 in the rumen by influencing the diversity and community structure of microbes such as bacteria, protozoa, and methanogens, thereby minimizing the loss of feed energy. Animal experiments showed that tea polyphenols significantly increased the concentrations of T-AOC and GSH-PX in bovine blood. In addition, by affecting the microbial community in the bovine rumen, tea polyphenols alter the fermentation patterns, thereby enhancing the host's rumen epithelial cells' capacity to transport VFAs. In production practice, the use of tea polyphenols can enhance the efficiency of nutrient utilization in dairy cows, thereby improving their productive performance. This study systematically investigated the effects of tea polyphenols on methane (CH4) production and the rumen epithelial cell transport capability in cattle using both in vitro and animal experiments, employing multi-omics techniques. The in vitro results demonstrated that, compared to the control group, tea polyphenols significantly reduced CH4 production and the acetate/propionate ratio (p < 0.05). Tea polyphenols reduced CH4 production by inhibiting the relative abundance of unclassified_d_Archaea methanogens and the protozoa Pseudoentodinium and g__Balantioides. The animal experiments showed that tea polyphenols significantly increased the concentrations of T-AOC and GSH-PX in bovine blood (p < 0.05). In addition, microbial groups such as Rikenellaceae_RC9_gut_group, Ruminococcaceae_NK4A214_group, and Butyrivibrio_2 were significantly enriched in the ruminal fluid of the tea polyphenol group (p < 0.05). The proteomic results indicated significant upregulation of proteins such as COIII, S100A8, FABP1, SLC2A8, and SLC29A1 (p < 0.05) and downregulation of proteins including HBB, RAB4A, RBP4, LOC107131172, HBA, and ZFYVE19 (p < 0.05), with FABP1 showing a positive correlation with propionate concentration, and RAB4A had a negative correlation (p < 0.05). Overall, tea polyphenols modulate the microbial composition within the rumen, inhibiting CH4 production and enhancing the host's rumen epithelial cell transport capacity for volatile fatty acids. [ABSTRACT FROM AUTHOR]

Simple Summary: Dietary energy level impacts rumen function and the microflora in ruminants, which are closely related to their growth and well-being. This study explored how dietary energy levels affect sheep's growth performance, nutrient digestibility, rumen fermentation, barrier function, and microflora. Our findings indicated that the average daily weight gain and nutrient digestibility improve with the increase of dietary energy. Meanwhile, the concentration of total volatile fatty acids and propionate in rumen increased, which indicated the enhancement of rumen fermentation. The content and expression of tight junction proteins, which represents rumen barrier function, increased with the increase of dietary energy. In addition, the bacterial diversity in rumen decreased, and the relative abundance of some bacteria like Prevotellaceae, Muribaculaceae, Saccharofermentans, Prevotella and Succiniclasticum changed at the family and genus levels. Ultimately, the growth performance, fermentation characteristics and barrier function were the best when the daily dietary metabolizable energy was 9.8–10.4 MJ/kg. This study revealed the complex interaction between diet, microbiota, and rumen health, ultimately guiding the development of more effective and scientifically informed animal feeding strategies. Dietary energy is crucial for ruminants' performance and health. To determine optimal dietary energy levels for growing sheep, we evaluated their growth performance, nutrient digestibility, rumen fermentation, barrier function, and microbiota under varying metabolic energy (ME) diets. Forty-five growing Yunnan semi-fine wool sheep, aged 10 months and weighing 30.8 ± 1.9 kg, were randomly allocated to five treatments, each receiving diets with ME levels of 8.0, 8.6, 9.2, 9.8 or 10.4 MJ/kg. The results showed that with increasing dietary energy, the average daily gain (ADG) as well as the digestibility of dry matter (DM) and organic matter (OM) increased (p < 0.05), while the feed conversion ratio (FCR) decreased linearly (p = 0.01). The concentration of total VFA (p = 0.03) and propionate (p = 0.01) in the rumen increased linearly, while rumen pH (p < 0.01) and the acetate–propionate ratio (p = 0.01) decreased linearly. Meanwhile, the protein contents of Claudin-4, Claudin-7, Occludin and ZO-1 as well as the relative mRNA expression of Claudin-4 and Occludin also increased (p < 0.05). In addition, rumen bacterial diversity decreased with the increase of dietary energy, and the relative abundance of some bacteria (like Saccharofermentans, Prevotella and Succiniclasticum) changed. In conclusion, increasing dietary energy levels enhanced growth performance, nutrient digestibility, rumen fermentation, and barrier function, and altered the rumen bacterial community distribution. The optimal dietary ME for these parameters in sheep at this growth stage was between 9.8 and 10.4 MJ/kg. [ABSTRACT FROM AUTHOR]

Simple Summary: This study indicates that a high grain diet (HG) significantly reduces the milk fat content of lactating cows. In addition, the HG group promoted rumen fermentation by altering the microbial composition of lactating cows. The concentration of short-chain fatty acids (SCFAs) in the HG group was increased by increasing the abundance of Prevotella and Xanthomonas, providing more energy to the body, while increasing the abundance of Stenotrophomonas, which increased the probability of mastitis. However, 16S sequencing still cannot reflect the true physiological changes in the host. Therefore, future research should investigate the effects between diet, microorganisms, and hosts to facilitate managers to use high-grain diets rationally to achieve high yields. The objectives of the current study were to evaluate the fluctuations in production performance, rumen fermentation, and microbial community in lactating dairy cows fed a high-grain diet (HG). In this study, 16 healthy Holstein lactating dairy cattle with similar milk yields of 16.80 ± 4.30 kg/d, days in milk 171.44 ± 23.25 days, and parity 2.2 ± 1.5 times were selected and randomly allocated into two groups. One group was fed a low-grain diet (LG; 40% concentrate, DM basis; n = 8), and the other group was fed a high-grain diet (HG; 60% concentrate, DM basis; n = 8). The experiment lasted 6 weeks, including 1 week for adaptation. The experimental results showed that the milk fat content in the milk of lactating cows in the HG group was significantly reduced (p < 0.05), and the milk urea nitrogen (MUN) content showed an increasing trend (0.05 < p < 0.10) compared with the LG group. Compared with the LG group, rumen fluid pH was significantly decreased after feeding a high-grain diet, and contents of total volatile fatty acids (TVFA), acetate, propionate, and butyrate were significantly increased (p < 0.05). The acetate/propionate significantly decreased (p < 0.05). HG group significantly increased the abundance of Prevotella and Bacteroides in rumen fluid while significantly reducing the abundance of Methanobrevibacter and Lachnospiraceae ND3007_group (p < 0.05). Microorganisms with LDA scores > 2 were defined as unique, with the bacterial genus Anaerorhabdus_furcosa_group identified as a biomarker for the LG group, and the unique bacterial genus in the HG group were Prevotella, Stenotrophomonas, and Xanthomonadaceae. The prediction results of microbial function showed that a total of 18 KEGG differential pathways were generated between the two treatment groups, mainly manifested in metabolic pathways, signal transduction, and the immune system. In conclusion, the HG group promoted rumen fermentation by altering the microbial composition of lactating cows. Our findings provide a theoretical basis for the rational use of high-grain diets to achieve high yields in intensive dairy farming. [ABSTRACT FROM AUTHOR]

Simple Summary: Adding the phytoactive mixture to the dairy cows' diet positively affected animal nutrition and health, improving Jersey production efficiency. The intake of phytogenics improved milk quality, reduced somatic cell counts, and increased unsaturated fatty acids. The intake of phytogenics per cow protected the mammary gland from bacteria Streptococcus spp. The phytoactive mixture directly affected the digestibility and modulation of the volatile fatty acid profile. The phytoactive mixture positively affected immune and antioxidant responses and anti-inflammatory action. This study's objective was to evaluate whether adding a combination of phytoactive (microencapsulated essential oils, minerals, turmeric extract, tannin, prebiotic, and probiotic) to the feed of lactating Jersey cows positively affects the production, composition, and quality of milk, rumen environment, and animal health. Fourteen Jersey cows were divided into two groups (control and phytogenic) for an experiment with two lactation phases of 45 days each (early lactation and mid-lactation). During the experiment, milk production was higher at various times in cows that consumed phytoactive, and these animals had the best feed efficiency. In mid-lactation, phytoactive intake increased nutrient digestibility. The number of lymphocytes in the blood is reduced when cows consume phytoactive substances. Globulin levels increased in these cows fed with the additive, which may be related to a higher concentration of immunoglobulins, especially IgA. Cows fed phytoactives had lower ceruloplasmin and haptoglobin concentrations. Lower serum lipid peroxidation, associated with greater glutathione S-transferase activity, is a good health indicator in cows that consume phytoactive substances. The higher concentration of volatile fatty acids was due to the higher proportion of acetic acid in the ruminal fluid combined with lower butyric acid. Somatic cell counts in milk were lower in cows that consumed phytoactives during mid-lactation, as well as the effect of the treatment on Streptococcus spp. (lower in cows that consumed the additive). We conclude that consuming the additive benefits cows' health modulates rumen fermentation and nutrient digestibility, and positively affects milk production and quality. [ABSTRACT FROM AUTHOR]

Simple Summary: Lamb fattening is the main production model of mutton sheep farming because it can produce high-quality meat. In order to meet the requirements of nutrients, the fattening lambs are often provided a high-concentrate diet for maintaining productivity. However, during the lamb period, the functions of the immune and digestive organs are relatively low. Long-term feeding of a high-concentrate diet further aggravates the damage to the gastrointestinal tracts and the oxidative stress of lambs. Thus, alleviating oxidative stress and promoting healthy growth of fattening lambs are of great significance in the intensive feeding of the mutton sheep industry. Our experiment studied the effects of tannin supplementation on the growth performance, rumen fermentation, apparent digestibility, and serum antioxidant and immune indexes in fattening lambs fed a high-concentrate diet. The results of this study indicate that tannin can be used as an effective additive to improve immunity and antioxidant ability in fattening lambs. This experiment aimed to study the effects of tannin supplementation on growth performance, rumen fermentation characteristics, apparent digestibility and serum biochemistry, and antioxidant and immune indexes in fattening lambs. A total of 36 male Hu sheep lambs (body weight = 15.83 ± 0.48 kg and days of age = 55 ± 2 d) were fed a high-concentrate diet and randomly divided into one of three groups of 12 animals each: control with no tannin (CON) and tannin treatments (TA1, 3 g/d per lamb; TA2, 6 g/d per lamb). The feeding experiment lasted for 60 d. The results showed that the average daily gain and ruminal propionate content of lambs in the TA1 group were higher (p < 0.05) than those in the CON group. Lambs fed tannin had significantly increased (p < 0.05) microbial protein and decreased (p < 0.05) ammonia nitrogen concentrations in the rumen. In addition, the crude protein and neutral detergent fiber digestibility of the TA2 group were significantly decreased (p < 0.05) as compared with the TA1 and CON groups, respectively. The serum concentrations of triglyceride, immunoglobulin A, and catalase and the total antioxidant capacity were higher (p < 0.05) in the TA1 group that those in the CON group, whereas an opposite trend of urea nitrogen, interleukin-1β, and malondialdehyde was found between the two groups. Also, tannin supplementation increased (p < 0.05) Lactobacillus and decreased (p < 0.05) Salmonella counts in the feces of lambs. Taken together, tannin supplementation can improve the growth performance, immunity, and antioxidant ability of fattening lambs fed a high-concentrate diet. [ABSTRACT FROM AUTHOR]

The study of nutrient metabolism of ruminants is inseparable from the study of rumen fermentation. In recent years, the prices of corn and soybean meal are high, and often rely on imports. In order to avoid human and animal competition for food, in the environment of cost saving and efficiency, people are seeking precision nutrition. Dietary energy and protein levels are important for ruminants to maintain normal physiological requirements and ensure rumen fermentation. Volatile fatty acids are the main products of rumen fermentation and important substances of energy metabolism in ruminants, and microbial proteins in rumen provide the main protein nutrition for ruminants. Therefore, the effects of different energy nitrogen levels on rumen fermentation in ruminants were reviewed in this paper from two aspects (energy to nitrogen ratio and simultaneous release of energy to nitrogen), so as to provide reference for formulating precise diets. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Methane is a potent greenhouse gas produced during the ruminal fermentation and is associated with a loss of feed energy. Therefore, efforts to reduce methane emissions have been ongoing in the last decades. Methane production is highly influenced by factors such as the ruminal microbiome and host genetics. Previous studies have proposed to use the ruminal microbiome to reduce long-term methane emissions, as ruminal microbiome composition is a moderately heritable trait and genetic improvement accumulates over time. Lactation stage is another important factor that might influence methane production, but potential associations with the ruminal microbiome have not been evaluated previously. This study sought to examine the changes in ruminal microbiome over the lactation period of primiparous Holstein cows differing in methane intensity (MI) and estimate the heritability of the abundance of relevant microorganisms. Ruminal content samples from 349 primiparous Holstein cows with 14 to 378 DIM were collected from May 2018 to June 2019. Methane intensity of each cow was calculated as methane concentration/milk yield. Up to 64 taxonomic features (TF) from 20 phyla had a significant differential abundance between cows with low and high MI early in lactation, 16 TF during mid lactation, and none late in lactation. Taxonomical features within the Firmicutes, Proteobacteria, Melainabacteria, Cyanobacteria, Bacteroidetes , and Actinobacteria phyla were associated with low MI, whereas eukaryotic TF and those within the Euryarchaeota, Verrucomicrobia, Kiritimatiellaeota , and Lentisphaerae phyla were associated with high MI. Out of the 60 TF that were found to be differentially abundant between early and late lactation in cows with low MI, 56 TF were also significant when cows with low and high MI were compared in the first third of the lactation. In general, microbes associated with low MI were more abundant early in lactation (e.g., Acidaminococcus, Aeromonas , and Weimeria genera) and showed low to moderate heritabilities (0.03 to 0.33). These results suggest some potential to modulate the rumen microbiome composition through selective breeding for lower MI. Differences in the ruminal microbiome of cows with extreme MI levels likely result from variations in the ruminal physiology of these cows and were more noticeable early in lactation, probably due to important interactions between the host phenotype and environmental factors associated with that period. Our results suggest that the ruminal microbiome evaluated early in lactation may be more precise for MI difference, and hence, this should be considered to optimize sampling periods to establish a reference population in genomic selection scenarios. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. We investigated the short- and long-term effects of different forage types supplemented in preweaning dairy calves on growth performance, blood metabolites, rumen fermentation, bacterial community, and milk production during first lactation. A total of 60 healthy 30-d-old female Holstein calves were blocked by birth date and body weight and randomly assigned to 1 of 3 groups (n = 20): normal milk and pelleted starter feeding (CON), supplemented with chopped oat hay (OAH; 75.0 g/d per calf [DM basis]), or alfalfa hay (ALF; 75.0 g/d per calf [DM basis]). The forage supplementation started when calves were 30 d old (d 1 of the experimental period) and ended when they were 73 d old (d 44 of the experimental period, when calves were weaned). Milk and feed intakes and fecal consistency scores were recorded daily. Growth performance, rumen fluid, and blood samples were collected biweekly. After weaning, all the calves were integrated with the same barn and diets. After calving, the milk production was recorded daily. During the experimental period, the OAH group had greater solid feed and total DM intakes and greater rumen pH than the CON group (P ≤ 0.04), but had lower forage intake and CP digestibility than the ALF group (P ≤ 0.04). The ALF group had higher rumen pH and blood BHB concentration (P ≤ 0.04), lower fecal score (P = 0.02), and greater ether extract digestibility (P = 0.02) than the CON group. The ALF and OAH groups had lower concentrations of ruminal total VFA (P = 0.01). Still, the ALF group had a greater proportion of acetate and a relative abundance of cellulose degradation-related bacteria (Lachnoclostridium_1 and Oribacterium) and a lower relative abundance of inflammation-related bacteria (Erysipelotrichaceae_UCG-009) in the rumen compared with CON. Interestingly, the average milk production from 6 to 200 DIM was greater in the ALF group (P < 0.01), even though no significant effects were found on the rumen fermentation parameters and blood metabolites at 200 DIM. Generally, alfalfa hay supplementation in preweaning dairy calves had positive effects in the short- and long-term for rumen development, health status, and future milk production. [ABSTRACT FROM AUTHOR]

The sustainable meeting of the global quest for ruminant intensification dictates the need to identify alternative, eco-friendly, and safe feed ingredients. In this sense, macroalgae offer a new paradigm in sustainable ruminant feed supply. This study aimed to investigate the potential of sub-Antarctic macroalgae, including Lessonia flavicans, Macrocystis pyrifera, Gigartina skottbergii, and Ulva Lactuca, regarding their chemical composition, in vitro gas production, and CH4 production. A completely randomized design consisted of a 96 h (h) incubation that included four different species and a control (alfalfa hay) with buffered rumen fluid. In vitro total gas, fermentation characteristics, and CH4 production were evaluated. The highest and the lowest crude protein (CP) contents were for U. lactuca (185.9 g/kg) and G. skottsbergi (86 g/kg), respectively (p < 0.0001). All macroalage had lower levels of natural detergent fiber (NDF) and acid detergent fiber (ADF) compared to alfalfa hay (p < 0.0001). The highest potential of gas production (b) was for M. pyriphera (162.8 mL gas/g DM), followed by alfalfa (119.3 mL gas/g DM). However, G. skottsbergi and M. pyriphera showed the highest dry matter degradability at 96 h (68.49 and 67.62 mg/100 mg, respectively; p < 0.0001) and microbial crude protein (679.8 and 669.8 mg/g, respectively, p < 0.0001). All four tested algae produced lower amounts of methane compared to alfalfa hay (p < 0.0001). After 24 h of incubation, M. pyriphera, L. flavicons, G. skottsbergi, and U. lactuca reduced CH4 by 99.7%, 98.6%, 92.9%, and 79.8%, respectively, when compared with the control. Also, all tested algae had lower (p = 0.0001) CH4 production (ml CH4/g Dry matter degradability, DMD) than alfalfa hay. The current results suggest that M. pyriphera and L. flavicons are promising feed additives for ruminants with eco-friendly production and acceptable CP content and DMD that could effectively mitigate CH4 emissions. Overall, these findings suggest that macroalgae hold promise as a substitute feed source for sustaining ruminant production at the onset of global warming. [ABSTRACT FROM AUTHOR]

Simple Summary: This study explored the effects of different caffeine doses on nutrient digestion and fermentation in a simulated rumen environment. The main goal was to improve our understanding of how caffeine might influence these important metabolic processes in the rumen when a lactating cow diet is used. Here, we report that a dose of caffeine (50 ppm) improved the digestibility of dry/organic matter and starch while reducing the protozoa numbers and ammonia concentration, which are related to ruminal protein metabolism. However, higher caffeine doses (above 50 ppm) began to negatively impact these parameters. Our observations suggest that caffeine, a naturally occurring compound in several plants such as coffee, cacao, and tea, could potentially be used to enhance digestion and fermentation in ruminants. This research is valuable to our understanding of anaerobic fermentation in the rumen as it demonstrates the use of this plant secondary metabolite to enhance nutrient utilization and milk production and other benefits to management and the environment. Caffeine is a plant secondary metabolite, commonly known for its bioactivity properties. This molecule increases microbial activity during anaerobic digestion. The aim of this study was to determine the effects of caffeine doses on the rumen fermentation profile and nutrient digestibility when continuous culture fermenters were fed a lactating cow's diet. We hypothesize that adding caffeine doses into continuous culture fermenters with a rumen fluid inoculum will not affect anaerobic fermentation or nutrient utilization. Fermenters were fed twice a day (at 0800 and 2000 h) with an experimental diet of high-producing dairy cows (53.55 g/DM day; Forage:Concentrate ratio, F:C of 40:60). Four levels of caffeine (0 ppm, 50 ppm, 100 ppm, and 150 ppm) were added to the diets as a treatment. The experiment was arranged in a randomized complete block design. Two blocks of four fermenters were run in two replicated periods of ten days. Statistical analyses were conducted in SAS version 9.4 for Windows (SAS Institute Inc., Cary, NC, USA) using the GLIMMIX procedure. The addition of caffeine at a 50 ppm dose on continuous culture fermentation decreased the protozoal counts (Diplodinium spp.) (p = 0.03) and ammonia concentrations (p < 0.05). A treatment of 50 ppm of caffeine increased the DM, OM, and starch digestibility (p < 0.05). When caffeine doses increased further than 50 ppm, the OM, DM, and starch digestibility decreased linearly (p = 0.01). The total volatile fatty acids and fatty acid proportions were unaffected. However, the acetate-to-propionate ratio (A:P) tended to decrease linearly among treatments (p = 0.07). The means of pH measurements and maximum pH had a significantly linear decrease effect (p < 0.01). Caffeine may represent a potential rumen fermentation modifier for use in lactating cow diets. [ABSTRACT FROM AUTHOR]

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This experiment was conducted to determine the nutrient composition of three agricultural by-products, namely garlic peel, sweet potato vine, and cotton straw, calculate their relative feeding value, effective energy value, and other indexes, and comprehensively evaluate their nutrient value by combining with rumen in vitro fermentation technology, with the aim of providing data references for the development and utilization of non-conventional feed resources for ruminants. The results showed that: 1) the dry matter (DM), ash, ether extract (EE), and crude protein (CP) contents of cotton straw were significantly higher than the other two feeds (p < 0.05), while the acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of garlic peel were highly significantly higher than the others (p < 0.05); 2) the relative feed value (DMI, DDM, TDN, RFV, and RFQ) and effective energy value (GE, DE, ME, NEm, NEg, and NEL) indexes of cotton straw were significantly higher than garlic peel and sweet potato vine (p < 0.01); 3) after 48 h of in vitro fermentation, the dry matter degradation rate (IVDMD) of sweet potato vine was significantly higher than the other two feeds (p < 0.01), and the cumulative gas productions (mL) and estimated gas parameters (a, b, a + b, and c) of sweet potato vine were significantly (p < 0.01) higher than those of garlic peel and cotton straw; 4) the sweet potato vine had lower pH but higher NH3-N compared to garlic peel and cotton straw (p < 0.05). The sweet potato vine had higher propionate, iso-butyrate, butyrate, iso-valerate, and total VFA than the other two roughages, which also had the lowest acetate-to-propionate ratio. Garlic peel produced the lowest acetate, while it produced the highest valerate (p < 0.05). These findings demonstrate that all three by-products have high potential as livestock feed based on their nutritive value parameters. Comparatively, sweet potato vines exhibit higher feeding value due to their relatively moderate NDF content and superior rumen fermentation performance. [ABSTRACT FROM AUTHOR]

The ethanolic (EE) and hydroalcoholic (HE) extracts of Urochloa brizantha concentrations were developed with the aim of evaluating their effect on rumen fermentation using an in vitro gas production technique. The EE and HE presented 3.62 and 5.38 mg protodioscin/mL, respectively. Ten treatments were evaluated in a completely randomized factorial arrangement (2 × 4 + 2), where the main effects were two extracts (EE and HE) and four levels (50, 100, 150, and 200 mL of extract/kg of DM) plus two controls: one positive (25 ppm of monensin–MON) and one (with no additives–CTL). The extract treatments (EXT, EE, and HE) reduced colonization time by 33.59% compared to the MON. IVDMD (p < 0.001) and IVOMD (p < 0.0001) were negatively affected by EXT addition when compared to CTL. Additionally, EXT reduced the proportion of propionic acid and increased the proportion of butyric acid in relation to CTL and MON treatments. Both EE and HE extracts of U. brizantha were able to alter rumen fermentation kinetic, with HE showing a higher concentration of protodioscin. Further research is needed to optimize extraction methodologies, comprehensively profile secondary compounds, and conduct trials with varying doses to effectively assess the viability of U. brizantha extract as an additive. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to investigate the effects of storage temperature and preservation time on the fermentation characteristics of rumen fluid collected from six Hu sheep fed a high-forage diet. The storage temperatures were set at −80 °C and −20 °C, and the preservation times were labelled as follows: 0 d (fresh rumen fluid, D0), 7 d (D7), 14 d (D14), 30 d (D30), 60 d (D60), 120 d (D120), and 240 d (D240). A repeated-measures design was applied to analyze the fermentation characteristics of rumen fluid across each preservation time point and storage temperature. The results showed that storage temperature had no significant effects on pH value, ammonia nitrogen (NH3-N), microbial protein (MCP), and volatile fatty acid (VFA) concentration and proportion (p > 0.05). Specifically, the pH value increased on D7, D14, and D60 (p < 0.05), while the MCP concentration decreased on D7, D14, D30, D120, and D240 but increased on D60 (p < 0.05), and the concentration of NH3-N decreased on D14 (p < 0.05). The acetate concentration increased on D30, while the concentrations of propionate, butyrate, valerate, and total VFA increased on D60 (p < 0.05). The concentration of isovalerate decreased on D60, and isobutyrate and branched-chain VFA concentrations decreased on D120 (p < 0.05). The proportion of acetate increased on D30, while the butyrate and valerate proportions increased on D60, and the proportions of isovalerate, isobutyrate, and branched-chain VFA decreased on D60 (p < 0.05). For rumen fluid from a high-forage diet, the storage temperature (−80 °C and −20 °C) did not affect its fermentation characteristics, suggesting that rumen fluid could be preserved at −80 °C or −20 °C without altering its fermentation characteristics. The fermentation parameters of rumen fluid changed significantly after 7 days of preservation; hence, it is recommended to finish determining the fermentation parameters of rumen fluid within 7 days of collection. The concentrations and proportions of most VFA changed after 30 days of preservation; therefore, it is recommended that VFA determination should be completed within 30 days of rumen fluid collection. [ABSTRACT FROM AUTHOR]