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Hempseed cake is a byproduct of hempseed oil extraction and is potentially a useful source of protein and fiber for use in ruminant diets. However, data are lacking on the appearance and/or clearance of cannabinoids in tissues of animals fed hempseed cake. To this end, a rapid method for quantifying cannabinol (CBN), cannabidiol (CBD), cannabinolic acid (CBNA), cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), cannabichromenic acid (CBCA), cannabidivarin (CBDV), cannabidivarinic acid (CBDVA), tetrahydrocannabinol (THC) and tetrahydrocannabinolic acid (THCA) in cattle tissues, plasma, and urine was developed using rapid screen electrospray ionization mass spectrometry (RS-ESI-MS). Regression coefficients of matrix-matched standard curves ranged from 0.9946 to0.9999 and analyte recoveries averaged from 90.2 ± 15.5 to 108.7 ± 18.7% across all compounds. Limits of detection and quantification ranged from 0.05 to 2.79 ng · mL

Five ruminally and duodenally cannulated red angus steers (n = 5; initial body weight [BW] = 542 kg, SD = 40 kg) were used in a three-period Youden square design consisting of three 21-d periods, three treatments, and five steers (one or two steers per treatment within each period) to evaluate the effect of feeding hempseed cake on ruminal fermentation parameters, organic matter (OM) intake, total tract nutrient digestion, and nitrogen (N) balance in steers fed finishing diets. The control (CON) diet contained 75% dry-rolled corn, 20% corn silage, and 5% supplement (DM basis). The dried corn distillers grains plus solubles (DDGS) and hempseed cake (HEMP) diets contained 55% dry-rolled corn, 20% corn silage, 20% dried corn distillers grains plus solubles or hempseed cake, and 5% supplement (DM basis). Total ruminal volatile fatty acid concentration was greater (P0.01) in steers fed the HEMP diet than in steers fed the DDGS or CON diets. Ruminal fluid pH was not influenced (P = 0.93) by treatment. Organic matter intake tended (P = 0.07) to be greater and OM total tract digestibility was less (P = 0.03) in steers fed the HEMP diet compared with steers fed the DDGS or CON diets. Ruminal true and total tract apparent N digestibility was greater (P0.01) in steers fed the HEMP diet than steers fed the DDGS or CON diets. Duodenal flow of essential, nonessential, and total amino acids was not influenced (P ≥ 0.37) by dietary treatment, but the lack of response was likely because ruminally degradable protein (RDP) supply exceeded the RDP requirement. Steers fed the HEMP diet had greater (P0.01) N retention (g/d) than steers fed the DDGS diet, which was greater (P0.01) than steers fed the CON diet, suggesting that feeding hempseed cake improved utilization of N. Although inclusion of hempseed cake decreased total tract OM digestibility compared with dried corn distillers grains or corn, improvements in N utilization suggest that hempseed cake could be a useful alternative feed ingredient for finishing cattle diets.This experiment evaluated the effects of dietary inclusion of hempseed cake or dried corn distillers grains plus solubles on ruminal fermentation parameters, organic matter (OM) intake, total tract nutrient digestion, and nitrogen (N) balance in steers fed finishing diets. Steers were assigned to one of three dietary treatments (no byproduct [CON], 20% dried corn distillers grains plus solubles [DDGS], or 20% hempseed cake [HEMP]; dry matter basis). Hempseed cake had greater acid detergent fiber concentrations, which resulted in greater acid detergent fiber flow to the small intestine and reduced total tract organic matter digestibility in steers fed the HEMP diet than in steers fed the DDGS or CON diets. Steers fed the HEMP diet had greater ruminal and total tract N digestibility, and greater ruminal ammonia concentrations than steers fed DDGS or CON diets, suggesting that the crude protein in hempseed cake is degraded to a greater extent in the rumen and total tract. Although inclusion of hempseed cake decreased total tract OM digestibility compared with dried corn distillers grains or no byproduct, the observed greater ruminal and total tract N digestibility suggest that it could be a useful alternative feed ingredient for finishing cattle diets.

The objective of this experiment was to evaluate effects of postruminal flows of casein or glutamic acid on small intestinal starch digestion and to quantify changes in energy and nutrient balance. Twenty-four steers (body weight = 179 ± 4 kg) were duodenally infused with raw cornstarch (1.46 ± 0.04 kg/d) and either 413 ± 7.0 g casein/d, 121 ± 3.6 g glutamic acid/d or water (control). Measures of small intestinal starch digestion and nutrient excretion were collected across 4 d after 42 d of infusion and measures of respiration via indirect calorimetry were collected across 2 d after 48 d of infusion. Ileal starch flow was least among calves provided casein, but ileal starch flow was not different between glutamic acid or control. Small intestinal starch digestion tended to be greatest among calves provided casein, least for glutamic acid and intermediate for control. Casein increased ileal flow of ethanol soluble oligosaccharides compared to glutamic acid and control. Large intestinal starch digestion was not different among treatments. By design, N intake was greatest among cattle provided casein, intermediate among calves provided glutamic acid and least for control. Nitrogen retention was greater in response to casein compared to control and glutamic acid. Intake of gross energy from feed was similar across treatments, and gross energy from infusate was greatest for casein, intermediate for glutamic acid and least for control. Variation in gross energy intake from feed resulted in no difference in overall gross energy intake across treatments. Similar to measures of small intestinal starch digestion and N retention, casein increased calories of digestible energy and metabolizable energy, compared to glutamic acid and control, which did not differ. Postruminal infusions did not influence methane production, but heat production was greatest in steers infused with casein, intermediate for steers provided glutamic acid, and least for control. Overall, amounts of energy retained by casein tended to be nearly 34% greater than control, but glutamic acid had no impact on energy balance. Improvement in small intestinal starch digestion in response to casein increased energy and N retained; however, glutamic acid did not influence small intestinal starch digestion and energy or N balance in cattle, which seems to suggest that responses in small intestinal starch digestion to greater postruminal flows of glutamic acid become refractory across greater durations of time.Small intestinal digestion of starch can provide greater energy from dietary starch in comparison to ruminal fermentation, which can increase performance and improve feed efficiency in cattle fed starch-based diets; however, small intestinal starch digestion in cattle is restricted in comparison to nonruminant animals or to ruminal fermentation of starch. In this experiment, long-term increases in postruminal protein but not glutamic acid increased small intestinal starch digestion, and increases in small intestinal starch digestion resulted in improvements in nitrogen and energy balance. Responses in this study compared to previous reports may suggest effects of increased postgastric flows of glutamic acid in cattle are transient, but that effects of casein are not.

Increased efficiency of nutrient utilization can potentially be gained with increased starch digestion in the small intestine in ruminants. However, ruminants have quantitative limits in the extent of starch disappearance in the small intestine. The objective is to explore the nutritional and physiological constraints that contribute to limitations of carbohydrate assimilation in the ruminant small intestine. Altered digesta composition and passage rate in the small intestine, insufficient pancreatic α-amylase and/or small intestinal carbohydrase activity, and reduced glucose absorption could all be potentially limiting factors of intestinal starch assimilation. The absence of intestinal sucrase activity in ruminants may be related to quantitative limits in small intestinal starch hydrolysis. Multiple sequence alignment of the sucrase-isomaltase complex gives insight into potential molecular mechanisms that may be associated with the absence of intestinal sucrase activity, reduced capacity for intestinal starch digestion, and limitations in the efficiency of feed utilization in cattle and sheep. Future research efforts in these areas will aid in our understanding of small intestinal starch digestion and glucose absorption to optimize feeding strategies for increased meat and milk production efficiency.

The relationship between weather variables and dry matter intake (DMI) in beef steers was examined using daily intake data from 790 beef steers collected through a computer-controlled feeding system in nonsummer months. Daily data were condensed into weekly averages (N = 13,895 steer-weeks). The variables considered to predict DMI (2.50 to 23.60 kg/d) were body weight (197 to 796 kg), dietary net energy for maintenance (NEm; 0.79 to 2.97 Mcal/kg), ambient temperature (−23.73 °C to 21.40 °C), range of temperature (2.79 °C to 19.43 °C), dew point (−27.84 °C to 14.34 °C), wind speed (2.08 to 6.49 m/s), solar radiation (30.8 to 297.1 W/m2), and 2-wk lag (average of previous 2 wk’s values) and monthly lag (average of previous 4 wk’s values) of each weather variable. Toeplitz variance-covariance structure for repeated measures was used to determine the model to predict DMI, while accounting for the effects of body weight, dietary NEm, and other variables in the model. Two-week lag of ambient temperature interacted (P ≤ 0.005) with 2-wk lag of range of temperature, monthly lag of wind speed, 2-wk lag of solar radiation, and dew point to predict DMI. Interactions (P = 0.0001) between 2-wk lag of range of temperature vs. dew point and monthly lag of wind speed vs. 2-wk lag of solar radiation were also detected. This study reports important weather variables associated with differences in DMI of growing and finishing steers and will help improve the accuracy of DMI prediction equations for beef cattle. Improvements in the accuracy of predicting DMI should give producers better tools to plan and execute efficient feeding management programs. The R2 of the overall model was 0.8891.

Sixty-nine finishing steers were randomly assigned to one of two treatment groups: supplementation to provide 0 or 267 mg·d−1 of ractopamine hydrochloride (RAC) for 42 d. Twelve steers were slaughtered for tissue and blood collection. Final body weight (BW) tended to be greater with RAC supplementation. Ractopamine hydrochloride supplementation decreased liver mass as a percentage of BW. Pancreatic protein concentration, digestive enzyme activities, serum glucose, and insulin concentrations were not influenced by RAC supplementation. Ractopamine hydrochloride supplementation decreased the pancreatic:α-amylase:trypsin and serum urea nitrogen concentrations. These data suggest that RAC may influence pancreatic exocrine function in cattle.

Cereal rye has been utilized in multiple ways within cropping systems in the northern Great Plains. Rye has traditionally not been utilized as a suitable grain for growing and finishing calves. Previously, recommendations have limited the use of rye due to the negative effects of ergot ingestion. Recent hybrid rye germplasms have shown increased yields with decreased incidence of ergot. The aim of this study was to determine the effects of ground hybrid rye inclusion rate on dry matter intake (DMI), growth performance, and feed efficiency in backgrounding beef steers. Two hundred crossbred steers were shipped to the Carrington Research Extension Center near Carrington, ND, stratified by weight, and assigned to one of twenty pens (n = 10 steers/pen). Four treatments were used in a completely randomized block design to evaluate animal performance during backgrounding when fed partial or complete replacement of corn with rye as the concentrate source. Ground hybrid rye was substituted for DRC as follows: a basal diet formulated with 20% DRC: 0% ground hybrid rye (CON), 13.5% DRC: 6.5% ground hybrid rye (RYE1), 6.5% DRC: 13.5% ground hybrid rye (RYE2), or 0% DRC:20% ground hybrid rye (RYE3) on a dry matter basis. Steers were fed for a total of 56 days beginning Oct. 25, 2021. Interim weights were taken on Nov. 22, 2021, and final weights were taken Dec. 20, 2021. At the conclusion of the feeding period, cattle were weighed on two consecutive days to determine final body weight. Performance data including animal live weights, ADG, DMI and G:F ratio were calculated. The use of rye within the diet did not influence steer weight throughout the study (P = 0.11). No differences in ADG were detected throughout the study (P = 0.68). Steers fed diets containing hybrid rye had higher DMI (P = 0.03) and higher F:G (P = 0.04) during the first month of the study. Increased DMI during the initial month of backgrounding may promote improved intake and growth. Results from the study suggest that steers fed rye as a partial or sole grain in a high forage backgrounding diet weighed similar to calves fed corn as the sole concentrate source.

A growing number of studies have investigated the viability of feeding hemp by-products as livestock feedstuffs; however, their impact on livestock microbiomes remains unexplored. Here, we evaluated the effects of feeding hempseed cake (HSC) on the gastrointestinal, respiratory, and reproductive microbiota in beef heifers. Angus-crossbred heifers [19-months old; initial body weight (BW) = 494 ± 10 kg] were fed a corn-based finishing diet (10% forage) containing either 20% HSC (n = 15) or 20% corn distillers grains (Control, n = 16) for 111 days until slaughter. Individual feed intake, feeding behavior and BW were measured throughout the study. Rumen fluid and deep nasopharyngeal swabs (days 0 7, 42, 70 and 98), and vaginal and uterine swabs (at slaughter) were collected, and the microbiota assessed using 16S rRNA gene sequencing. HSC feeding resulted in reduced average daily gain (P = 0.05) without influencing feed intake and feeding behavior (P > 0.05) (reported elsewhere). Sampling time had a significant effect on both ruminal (PERMANOVA: R2 = 0.39; P < 0.001) and nasopharyngeal (R2 = 0.18; P < 0.001) microbial community structure. There was also a significant effect of diet on the ruminal (d7– 98; 0.06 ≤ R2 ≤ 0.12; P < 0.05), nasopharyngeal (d 42; R2= 0.18; P < 0.001), and vaginal (R2 = 0.06; P < 0.01) microbiota. Although microbial richness in the rumen, nasopharynx, vagina, and uterus was not affected (P > 0.05) by HSC feeding, microbial diversity (Shannon diversity) was increased in the rumen (d42-98) but reduced in the uterus of HSC heifers (P < 0.05). The relative abundance of five ruminal genera was enriched, while five vaginal genera were reduced in HSC heifers (P < 0.05). Overall, the results of our longitudinal study suggest that feeding hemp by-products can alter the bovine gut, respiratory and reproductive microbiota.

As the hemp industry continues to develop in the United States, there is an increasing interest in feeding byproducts of industrial hemp production to livestock. A completely randomized design experiment using crossbred finishing heifers (initial body weight [BW] ± SE = 494 ± 10 kg) was conducted to determine the effects of feeding hempseed cake in a corn-based finishing diet (10% forage) formulated to meet or exceed ruminally degradable and metabolizable protein requirements on growth performance, carcass characteristics, feeding behavior, and plasma parameters. Dietary treatments were the inclusion of 20% (dry matter [DM] basis) of dried corn distillers grains plus solubles (DDGS, n = 16) or hempseed cake (HEMP, n = 15). Cattle were housed in two pens, had ad libitum access to feed and water, and individual intakes and feeding behavior were monitored using the Insentec feeding system. Cattle were fed treatment diets for 111 d, and every 14 d BW were measured and blood samples were collected. Blood plasma was analyzed for glucose, urea nitrogen, and individual amino acids, and results were analyzed using repeated-measures analysis in SAS. Final BW, average daily gain, gain:feed, and hot carcass weight decreased (P ≤ 0.05) by 2.3%, 7.7%, 7.7%, and 2.6%, respectively, in heifers fed the HEMP diet than in heifers fed the DDGS diet. Net energy for maintenance and gain (Mcal/kg of feed, DM basis), estimated based on heifer intake and performance, were greater (P = 0.02) for the DDGS diet than for the HEMP diet. All other performance and carcass characteristics were not different (P ≥ 0.20) between treatments. Heifers fed the HEMP diet had greater (P 0.05) plasma urea nitrogen concentration in samples from each collection day compared with heifers fed the DDGS diet, although there was a treatment-by-day interaction (P 0.01) because of variability in the magnitude of treatment differences over time. Plasma glucose concentration was not influenced (P = 0.17) by dietary treatment. Plasma concentrations of total amino acids, nonessential amino acids, and essential amino acids were not different between treatments (P ≥ 0.09), although there were several interactions between treatment and day (P ≤ 0.04) for individual amino acids. These data suggest that hempseed cake has a lower net energy for maintenance and gain relative to DDGS when adequate metabolizable protein is supplied, while still providing adequate nutrition to support the acceptable performance of finishing cattle.This experiment evaluated the effects of dietary inclusion of hempseed cake in comparison with dried corn distillers grains plus solubles (DDGS) on growth performance, feeding behavior, carcass characteristics, and blood parameters in finishing heifers. Angus-crossbred heifers were assigned randomly to one of two treatments (20% hempseed cake [HEMP] or 20% DDGS; dry matter basis) and were fed for 111 d until slaughter. Heifers receiving the DDGS treatment had greater final body weights, average daily gain, gain efficiency, dietary concentration of net energy for maintenance and gain, and carcass weight than heifers fed the HEMP treatment. All other carcass characteristics, as well as feeding behavior, were not influenced by treatment. Plasma urea nitrogen was greater in heifers fed the HEMP diet compared with the DDGS diet, while glucose was not influenced by treatment. Several plasma amino acid concentrations were influenced by treatment. Although the inclusion of hempseed cake decreased growth performance, it could be a viable alternative feed source for cattle.

Six ruminally cannulated steers [475.0 ± 49.6 kg initial body weight (BW)] were used in a 6 × 3 incomplete Latin square design (six treatments and three periods), to evaluate the impacts replacing of corn silage with pelleted soyhulls as roughage in high-concentrate finishing diets containing 30% modified distillers grains with solubles. Treatments were based on increasing dietary inclusion of soyhulls and consisted of: (1) Control (0), roughage supplied by dietary inclusion of 20% corn silage [dry matter (DM) basis]; (2) 50% replacement of corn silage with soyhulls (50); (3) 100% replacement of corn silage with soyhulls (100), and the same three treatments repeated with 3% added wheat straw (DM basis) replacing corn in the diet (0S, 50S, and 100S, respectively). Absolute dry matter intake (DMI; kg/d basis) tended to decrease both linearly and quadratically (P ≤ 0.09) and proportional DMI (% of BW) decreased linearly (P = 0.04) with increasing soyhull inclusion but was not affected by the addition of straw in the diet (P = 0.68). Total tract digestibility of organic matter and crude protein were not affected by soyhull inclusion or added straw (P ≥ 0.32). Ruminal pH did not differ (P = 0.65) with increasing soyhull inclusion but increased with the addition of straw (P < 0.01; 5.9 vs. 6.1 for no straw and straw, respectively). Molar proportions of acetate and butyrate decreased while propionate increased with increased soyhull inclusion (P ≤ 0.03; linearly and quadratically, respectively). Ruminal fluid kinetics were unaffected by either rate of replacement of corn silage with soyhulls or wheat straw inclusion (P ≥ 0.13). Decreases in DMI observed in this study would likely decrease finishing cattle performance and underscores the need for additional research before recommending this practice to cattle feeders.

The hypothesis of this experiment was that dietary fructose would influence visceral organ mass, carbohydrase activity, and mRNA expression of carbohydrases and nutrient transporters in the small intestine in neonatal calves. Therefore, our objective was to use the neonatal calf as a model to evaluate the effects of postruminal fructose supply on small intestinal carbohydrate assimilation. Ten calves (

Two ruminally cannulated steers [928 ± 25.5 kg body weight (BW)] were fed alfalfa hay at 2.0% of BW and served as donors of rumen fluid. Treatments were early-bud alfalfa (CON) or a combination [dry matter (DM) basis] of 80% early-bud alfalfa with 20% of corn silage (CS), brome grass hay (BGH), soybean hulls (SBH), beet pulp (BP), corn grain (CORN), dried corn distillers’ grains with solubles (DDGS), or wheat middlings (MIDD). Tubes were incubated at multiple time points over a 72 h period and assessed for rate and extent of digestion. Samples were run in duplicate and replicated over 3 d. The potential extent of DM and organic matter (OM) degradation increased (P

BACKGROUND Small intestinal starch digestion in ruminants is potentially limited by inadequate production of carbohydrases. Previous research has demonstrated that small intestinal starch digestion can be improved by postruminal supply of casein or glutamic acid. However, the mechanisms by which casein and glutamic acid increase starch digestion are not well understood. OBJECTIVES The objective of this experiment was to evaluate the effects of duodenal infusions of starch with casein or glutamic acid on postruminal carbohydrase activities in cattle. METHODS Twenty-two steers [mean body weight (BW) = 179 ± 4.23 kg] were surgically fitted with duodenal and ileal cannulas and limit-fed a soybean hull-based diet containing small amounts of starch. Raw cornstarch (1.61 ± 0.0869 kg/d) was infused into the duodenum alone (control), or with 118 ± 7.21 g glutamic acid/d, or 428 ± 19.4 g casein/d. Treatments were infused continuously for 58 d and then steers were killed for tissue collection. Activities of pancreatic (α-amylase) and intestinal (maltase, isomaltase, glucoamylase, sucrase) carbohydrases were determined. Data were analyzed as a randomized complete block (replicate group) design using the GLM procedure of SAS to determine effects of infusion treatment. RESULTS Duodenal casein infusion increased (P

Pregastric fermentation along with production practices that are dependent on high-energy diets means ruminants rely heavily on starch and protein assimilation for a substantial portion of their nutrient needs. While the majority of dietary starch may be fermented in the rumen, significant portions can flow to the small intestine. The initial phase of small intestinal digestion requires pancreatic α-amylase. Numerous nutritional factors have been shown to influence pancreatic α-amylase secretion with starch producing negative effects and casein, certain amino acids and dietary energy having positive effects. To date, manipulation of α-amylase secretion has not resulted in substantial changes in digestibility. The second phase of digestion involves the actions of the brush border enzymes sucrase-isomaltase and maltase-glucoamylase. Genetically, ruminants appear to possess these enzymes; however, the absence of measurable sucrase activity and limited adaptation with changes in diet suggests a reduced capacity for this phase of digestion. The final phase of carbohydrate assimilation is glucose transport. Ruminants possess Na+-dependent glucose transport that has been shown to be inducible. Because of the nature of pregastric fermentation, ruminants see a near constant flow of microbial protein to the small intestine. This results in a nutrient supply, which places a high priority on protein digestion and utilization. Comparatively, little research has been conducted describing protein assimilation. Enzymes and processes appear consistent with non-ruminants and are likely not limiting for efficient digestion of most feedstuffs. The mechanisms regulating the nutritional modulation of digestive function in the small intestine are complex and coordinated via the substrate, neural and hormonal effects in the small intestine, pancreas, peripheral tissues and the pituitary-hypothalamic axis. More research is needed in ruminants to help unravel the complexities by which small intestinal digestion is regulated with the aim of developing approaches to enhance and improve the efficiency of small intestinal digestion.

Our research group demonstrated that vitamin A restriction affected meat quality of Angus cross and Simmental steers. Therefore, the aim of this study is to highlight the genotype variations in response to dietary vitamin A levels. Commercial Angus and Simmental steers (n = 32 per breed; initial BW = 337.2 ± 5.9 kg; ~8 months of age) were fed a low-vitamin A (LVA) (1017 IU/kg DM) backgrounding diet for 95 days to reduce hepatic vitamin A stores. During finishing, steers were randomly assigned to treatments in a 2 × 2 factorial arrangement of genotype × dietary vitamin A concentration. The LVA treatment was a finishing diet with no supplemental vitamin A (723 IU vitamin A/kg DM); the control (CON) was the LVA diet plus supplementation with 2200 IU vitamin A/kg DM. Blood samples were collected at three time points throughout the study to analyze serum retinol concentration. At the completion of finishing, steers were slaughtered at a commercial abattoir. Meat characteristics assessed were intramuscular fat concentration, color, Warner-Bratzler shear force, cook loss and pH. Camera image analysis was used for determination of marbling, 12th rib back fat and longissimus muscle area (LMA). The LVA steers had lower (P < 0.001) serum retinol concentration than CON steers. The LVA treatment resulted in greater (P = 0.03) average daily gain than the CON treatment, 1.52 and 1.44 ± 0.03 kg/day, respectively; however, there was no effect of treatment on final BW, DM intake or feed efficiency. Cooking loss and yield grade were greater and LMA was smaller in LVA steers (P < 0.05). There was an interaction between breed and treatment for marbling score (P = 0.01) and percentage of carcasses grading United States Department of Agriculture (USDA) Prime (P = 0.02). For Angus steers, LVA treatment resulted in a 16% greater marbling score than CON (683 and 570 ± 40, respectively) and 27% of LVA Angus steers graded USDA Prime compared with 0% for CON. Conversely, there was no difference in marbling score or USDA Quality Grades between LVA and CON for Simmental steers. In conclusion, feeding a LVA diet during finishing increased marbling in Angus but not in Simmental steers. Reducing the vitamin A level of finishing diets fed to cattle with a high propensity to marble, such as Angus, has the potential to increase economically important traits such as marbling and quality grade without negatively impacting gain : feed or yield grade.

To determine the effects of maternal nutrient restriction and re-alimentation on fetal liver and muscle development, 48 pregnant ewes with singletons, were fed a control diet [100% National Research Council (NRC) requirements (CON)] starting at the beginning of gestation. On day 50 of gestation, ewes (n = 7) were euthanized and fetal liver and skeletal muscle samples were collected. The remaining animals were fed either CON or 60% NRC requirements (RES), a subset were euthanized at day 90 of gestation (n = 7/treatment), and fetal samples obtained. Remaining ewes were maintained on the current diet (CON-CON, n = 6; RES-RES, n = 7) or switched to alternative diet (CON-RES, RES-CON; n = 7/treatment). On day 130 of gestation, remaining ewes were euthanized, and fetal samples collected. Fetal liver was analyzed for general tissue morphology, and fetal skeletal muscles were analyzed for lipid accumulation. mRNA expression of growth and metabolic factors were quantified in liver and muscle tissues. Hepatocellular vacuolation was increased in RES-CON and RES-RES compared with CON-CON and CON-RES (P < 0.01). In semitendinosus and triceps brachii, intramyocellular lipid content increased 19% and 15%, respectively, in RES-CON and RES-RES compared with CON-CON and CON-RES (P£0.02) and in longissimus dorsi, lipid content was decreased 7% in CON-RES and RES-RES compared with CON-CON and RES-CON (P=0.01). In liver, insulin-like growth factor binding protein-1, glycogen synthase 2, and pyruvate dehydrogenase kinase 1 expression increased 1.92-fold, 1.45-fold, and 1.47-fold, respectively (P£0.03) in CON-RES and RES-RES compared with RES-CON and CON-CON. In LD, IGF1-R expression increased 3.19-fold in CON-RES and RES-RES compared with RES-CON and CON-CON (P = 0.05). These results demonstrate that maternal nutrient restriction followed by re-alimentation restores liver and muscle gene expression of growth and metabolic factors while negatively impacting liver composition and muscle lipid content potentially leading to altered tissue function and metabolism later in life. Supported by USDA-AFRI grants 2016-67016-24884 and 2017-67016-26568.

Average daily gain is one of the most important measures producers utilize to measure productivity of beef cattle. The objective was to examine how weather variables influence ADG. Data from 790 beef steers collected using an Insentec feeding system were utilized for this study. Intake data were condensed from daily data into weekly averages (n = 13,739 steer-weeks). The variables considered were ADG (-3.0 to 4.86 kg/d), DMI (2.50 to 21.77kg/d), BW (197.3 to 796.1 kg), dietary energy density (NEm; 1.2 to 2.5 Mcal/kg), average ambient temperature (-23.7 to 21.4 °C), range of temperature (2.8 to 19.4 °C), dew point (-27.8 to 14.3 °C), wind speed (2.08 to 6.49 km/h), solar radiation (30.8 to 297.1 W/m2), and two weeks lag (average of previous two weeks values) and monthly lag (average of previous four weeks values) of each weather variable. Relationship between weather variables were considered while developing the model, including controlling for confounding variables. Residuals of ADG generated after fitting week of year as a fixed effect were used in scatter plots with explanatory variables to identify if non-linear relationships existed. The MIXED procedure of SAS was used to assess the fit and regression parameters of explanatory variables as fixed covariates. Repeated measures were handled using the REPEATED statement and within-individual relationship was accounted for using the Toeplitz covariance structure. Body weight and energy density had linear and quadratic relationships with ADG (Table 1). Two weeks lag of wind speed and monthly lag of solar radiation had positive and negative associations with ADG, respectively, and there were several interactions between weather variables. These data indicate that weather variables influence ADG and should be considered in ADG prediction equations.

Objectives were to evaluate the effects of feeding a vitamin and mineral (VTM) supplement to beef heifers during gestation on calf performance, body measurements, trace mineral status, and organ weights at 30 h after birth. We hypothesized that VTM supplementation during gestation would improve mineral status in the neonatal calf but not impact calf performance parameters and body and organ weights at 30 hours after birth. Fourteen Angus-based heifers [initial body weight (BW)] = 273.7 ± 1.10 kg) were randomly assigned to receive either a basal diet (CON; n = 7) or a basal diet plus a VTM supplement (VTM; n = 7; 113 g•heifer-1•d-1, targeting gain of 0.45 kg/day) from 60 d pre-breeding through gestation. Immediately after parturition, blood samples were collected from dams and calves, then calves were separated from their dams. Calves were fed one feeding of colostrum replacer, followed by milk replacer every 12 h, then euthanized at 30 h. Body weight and measurements were recorded, then organs and viscera were removed, weighed, and sampled. Dam serum and neonatal serum, liver, and blood were analyzed for concentrations of minerals. Data were analyzed using the GLM Procedure of SAS with individual animal as the experimental unit. Dietary treatments did not impact calf weight (0 h or 30 h), calf body measurements, or body weight of the dam at calving (P ≥ 0.32). Further, neonatal organ weights were not influenced (P ≥ 0.21) by maternal VTM treatment. Concentrations of Se and Co in calf serum and Se in calf liver were increased (P ≤ 0.02) by VTM treatment; however, concentrations of Cu, Mn, Mo, and Zn in calf muscle, liver, and serum were not impacted (P ≥ 0.07) by VTM treatment. Concentrations of Co in serum of the dam was the only mineral affected by dietary treatments, being greater (P = 0.001) in VTM than CON dams. In the current experiment providing trace mineral supplementation throughout gestation did not impact calf weight or body measurements at birth. However, the implications of altered mineral status of the neonatal calves at birth, and presumably throughout gestation, may have additional postnatal effects that warrant further investigation.

Feeding high-grain diets can result in reduced ruminal pH, inflammation of ruminal and other tissues, and subacute ruminal acidosis. Vasoactive intestinal polypeptide (VIP), a gut hormone with anti-inflammatory and other functions, could have a beneficial role in ruminants fed high-concentrate diets. To determine the effects of VIP injection on dry matter intake, average daily gain, gain:feed, and ruminal pH, wether lambs (n=16; BW=68.5 ±1.8 kg) were blocked by body weight and randomly assigned to VIP treatment (n=8) or control (n=8). All lambs were housed in individual pens, adapted to the same high concentrate diet (75% whole corn and 25% supplemental pellet; DM basis), and feed intake and average daily gain were measured from day 1 to 21 when lambs were placed in metabolism crates. Lambs in the treatment group were injected intraperitoneally with VIP (1.3 nmol/kg BW in 0.9% NaCl), whereas lambs in the control group were injected with 0.9% NaCl every second day over 28 days. Nutrient balance was measured over the final seven days (data will be reported elsewhere), and lambs then were slaughtered and ruminal fluid and tissues collected. The average daily gain was greater (p = 0.04) in VIP treated lambs than in control lambs. However, no difference (p > 0.05) in daily feed intake was observed between treatments. Ruminal fluid pH was not significantly influenced by treatment (5.2±0.11 vs 5.0±0.11 for the control and VIP treatments, respectively). These data indicate that VIP injection may increase ADG and gain:feed in lambs fed high concentrate diets. Further research is needed to verify these results and to delineate the mechanisms responsible for the observed increases in ADG and gain:feed.

There is interest in feeding industrial hemp production byproducts to livestock, but little is known about the digestibility and ruminal fermentation parameters associated with this feedstuff. A nutrient balance experiment using crossbred steers (n = 5; initial BW = 542 kg, SD = 40 kg) in a Youden square design was conducted to evaluate the effects of feeding hempseed cake (HEMP) or dried corn distillers grains plus solubles [DDGS; each included at 20% of diet dry matter (DM) in respective treatments] in comparison with a dry-rolled corn-based negative control treatment (CON) on ruminal fermentation parameters, nutrient digestibility, nutrient flow and nitrogen (N) balance. Organic matter (OM) tended (P = 0.07) to increase and OM total tract apparent digestibility decreased (P = 0.03) in steers fed the HEMP diet compared with steers fed the DDGS and CON diets. Total tract apparent N digestibility was greatest (P < 0.01) in steers fed the HEMP diet, while total tract apparent digestibility in all other nutrients was not influenced (P ≥ 0.13) by treatment. Furthermore, apparent ruminal digestibility of OM was greatest (P < 0.01) in steers fed the HEMP or CON diets, and neutral detergent fiber, acid detergent fiber (ADF), and true ruminal digestibility of N was greatest (P ≤ 0.04) in steers fed the HEMP diet. Ruminal total amino acid degradation and total ruminal VFA concentration was greatest (P < 0.01) in steers fed the HEMP diet. A treatment by hour interaction (P = 0.01) was observed for ruminal ammonia concentration. Nitrogen retention was greatest (P < 0.01) in steers fed the HEMP diet, suggesting that feeding hempseed cake improved utilization of N. These results suggest that although ruminal digestibility of all nutrients is greater in steers fed the HEMP diet, greater ADF concentration in hempseed cake negatively influences total tract apparent OM digestibility when fed to finishing steers.

Hempseed cake, a byproduct of industrial hemp and subsequent hempseed oil extraction processes, contains cannabinoids and fatty acids that could be potentially therapeutic for livestock, but little is known about the extent to which hempseed cake can influence immune response variables of cattle. An endotoxin challenge experiment using crossbred steers (n = 5; initial BW = 542 kg, SD = 40 kg) was conducted to evaluate the effects of hempseed cake treatment (HEMP) and dried corn distillers grains plus solubles treatment (DDGS; each included at 20% of diet DM in respective treatments) in comparison with a dry-rolled corn-based negative control treatment (CON) on plasma glucose, non-esterified fatty acids (NEFA), urea nitrogen (PUN), rectal temperature, twelve cytokine (IFNγ, IL-1α, IL-6, IL-8, IL-10, IL-36RA, IP10, MCP-1, MIP-1α, MIP-1β, TNFα, and VEGF-A), and amino acid concentrations at five timepoints after administration of endotoxin (lipopolysaccharide; LPS). Steers were administered LPS at 0.25 μg/kg BW, and blood was collected via jugular venipuncture before and 1, 2, 4 and 6-hours post-bolus injection. Data were analyzed as repeated measures using the MIXED procedure of SAS, and pre-bolus values was used as a covariate. A treatment by hour interaction (P = 0.04) was observed for PUN, and pre-bolus PUN was greatest (P < 0.01) in steers fed the HEMP. Plasma IL-1α, IL-36RA, and TNF-α were least (P ≤ 0.02), while IL-10 and MIP-1α tended (P ≤ 0.10) to be less in steers fed the HEMP diet. Plasma isoleucine, leucine, tryptophan, and tyrosine concentrations were greatest (P ≤ 0.04) in steers fed the DDGS diet, plasma aspartic acid and glycine concentrations were greatest (P ≤ 0.02) for steers fed the DDGS and CON diets. Overall, these data suggest that hempseed cake has potential to reduce inflammation by influencing cytokine production, but more research is needed to further understand animal growth performance and health implications.

Insulin concentrations are variable in bovine colostrum (5 to 263 µg insulin/L) and its effects on gastrointestinal function in neonatal calves are unknown. The objective of this study was to determine if varying concentrations of insulin in colostrum would influence intestinal carbohydrases in neonatal Holstein bulls. Calves (n = 26; 49.11 kg, SD = 3.24) were removed from their dams after calving. They were fed 3 meals of colostrum (7% BW or 3.10 ± 0.02 L) at 2, 14 and 26 hours after birth containing one of 3 insulin concentrations: basal (16.8 µg/L; n = 8), or supplemental colostrum containing either a 5× (83.4 µg/L; n = 10) or 10× (167.5 µg/L; n = 8) increase in colostrum insulin respective to basal concentrations. At 30 hours, the animals were killed, and the gastrointestinal tract was removed for mucosal scrapings of the duodenum, proximal jejunum, and ileum. Intestinal mucosal scrapings were assayed for the following brush border carbohydrases: maltase, isomaltase, lactase and glucoamylase. Data were analyzed using the MIXED procedure of SAS with treatment and dam parity modeled as fixed effects. There was no treatment effect (P > 0.05) on intestinal maltase, isomaltase and glucoamylase concentrations. However, there was a linear increase (P < 0.05) in jejunal lactase activity (Unit/g of jejunum and U/g of protein) with increasing amount of insulin inclusion. These data indicate that insulin supplementation has minimal effects on activities of brush border starch degrading enzymes, but increases lactase activity in the proximal jejunum of neonatal calves.

Maternal nutrient restriction during gestation adversely affects offspring growth and development of liver and skeletal muscle tissues. Realimentation following nutrient restriction may alleviate these negative impacts on development but may alter metabolism and tissue composition. Forty-eight ewes, pregnant with singletons, were fed to meet 100% National Research Council (NRC) recommendations starting at the beginning of gestation. On day 50 of gestation, seven ewes were euthanized (BASE), and fetal liver, skeletal muscles, and blood samples were collected. The remaining animals were fed either 100% of NRC recommendations (CON) or 60% NRC recommendations (RES), a subset were euthanized at day 90 of gestation (n = 7/treatment), and fetal samples were collected. Remaining ewes were maintained on the current diet (CON-CON, n = 6; RES-RES, n = 7) or switched to the alternate diet (CON-RES, RES-CON; n = 7/treatment). On day 130 of gestation, the remaining ewes were euthanized, and fetal samples were collected. At day 130 of gestation, maternal nutrient restriction during late-gestation (RES-RES and CON-RES) decreased fetal liver weight (P < 0.01) and cross-sectional area in triceps brachii (P = 0.01; TB), longissimus dorsi (P = 0.02; LM), and semitendinosus (P = 0.05; STN) muscles. Maternal nutrient restriction during mid-gestation increased hepatocyte vacuole size at day 130 of gestation. Late-gestational maternal nutrient restriction increased mRNA expression of insulin-like growth factor (IGF) binding protein-1 (P < 0.01), glycogen synthase 2 (P = 0.01; GYS2), and pyruvate dehydrogenase kinase 1 (P < 0.01; PDHK1) in the liver and IGF receptor 1 (P = 0.05) in the LM. Lipid concentration in the LM was decreased by late-gestational nutrient restriction (P = 0.01) and increased by mid-gestational nutrient restriction in STN (P = 0.03) and TB (P < 0.01). Principal component analysis of lipidomics data demonstrated clustering of principal components by day of gestation and elastic net regression identified 50, 44, and 29 lipids that classified the treatments in the fetal liver, LM, and blood, respectively. In conclusion, restricting maternal nutrition impacts fetal liver and muscle morphology, gene expression, and lipid metabolism, whereas realimentation attenuated some of these effects. Therefore, realimentation may be a viable strategy to reduce the impacts of nutrient restriction, but can lead to alterations in lipid metabolism in sheep.

To determine the effects of grain type (rolled-corn vs. rolled-barley) and dried corn distillers’ grains with solubles (DDGS) oil concentration (low = 4.5% vs. moderate = 7.9%) on ruminal pH, ammonia (NH3) and volatile fatty acid (VFA) concentrations, in vitro enteric methane (CH4) and carbon dioxide (CO2) production, and digestive enzyme activity, eight ruminally cannulated Holstein steers (715 ± 61.4 kg) were used in a 4 × 8 Latin rectangle with a 2 × 2 factorial arrangement of treatments. Diets were offered for ad libitum intake. Experimental periods were 24 d with 7 d of diet adaptation, 7 d of sample collection, and a 10 d transition between periods. No differences were observed for ruminal NH3, total VFA concentration, pH, or in vitro concentration of CH4 or CO2 after 24 h of incubation among treatments. The lag time for in vitro gas production and degradation was greater (P = 0.03) from steers fed diets containing rolled-corn than rolled-barley. There were grain type × DDGS interactions (P ≤ 0.02) observed for α-amylase and trypsin activity (U L−1 ruminal fluid). Maltase activity (U L−1 ruminal fluid) was greater (P ≤ 0.01) in steers fed diets containing rolled-corn than rolled-barley and in steers fed diets containing low- compared with moderate-oil DDGS. These results indicate that, although ruminal enzyme activity was influenced, feeding different grain types (rolled-corn vs. rolled-barley) or DDGS with differing oil concentration (moderate vs. low) did not negatively influence ruminal fermentation or in vitro CH4 production.

Using swine as a biomedical model, this study examined whether consumption of added protein (red meat) or free sugar (glucose) throughout gestation and lactation will affect milk composition. Multiparous sows were fed an isocaloric supplement in addition to their normal corn-soybean meal base diet starting on day 40 of gestation and throughout lactation: cooked ground beef (BEEF; n = 10); free sugar (SUG; n = 9); a mixture of the BEEF and SUG diet (BEEFSUG; n = 7); or a caloric equivalent of the base diet (CONTROL; n = 8). Milk samples (30 mL) were collected from each sow at days 0, 6, 12, and 18 of lactation by hand-milking teats after intramuscular injection of 1 cc of oxytocin. Milk was frozen at -20 °C until analyzed for percentage of fat, protein, lactose, total solids, other solids, and milk urea nitrogen (MUN). Analyses were conducted using the mixed procedure in SAS. For traits occurring over time, a repeated measures statement was used with sow as the subject and the best fit method based on AICC was chosen. There was a day × treatment interaction (P < 0.01) for fat and lactose. There were no significant treatment effects within a day for fat when evaluating mean separations. While percentages were similar across treatment groups on days 0, 6, and 12 for lactose, SUG sows had decreased lactose on day 18 compared to CONTROL and BEEFSUG sows (P = 0.02 and 0.04), with no other significant differences between treatments. There were no treatment or treatment ×day interactions for protein, MUN, total solids or other solids. There was a main effect of day where protein decreased from day 0 to 12; MUN decreased between days 6 and 18; total solids decreased from day 0 to 6; and other solids increased from day 0 to 6 and further increased on day 12. Consumption of a maternal supplementation may impact the percentage of lactose in milk.

This experiment evaluated the influence of protein supplementation frequency (SF) and amount offered on intake, nutrient digestibility, and ruminal fermentation by rumen-fistulated beef steers consuming low-quality [2.9% crude protein (CP); dry matter (DM) basis], cool-season forage. Seven Angus × Hereford steers (300 ± 27 kg) fitted with ruminal cannulas were randomly assigned to 1 of 7 treatments in an incomplete 7 × 4 Latin square. Treatments, in a 2 × 3 factorial design plus a non-supplemented control (CON), consisted of 2 levels of supplemental soybean meal, 100% (F) or 50% (H) of the estimated rumen-degradable protein requirement, provided daily (D), once every 5 d (5D), or once every 10 d (10D). Experimental periods were 30 d and dry matter intake (DMI) was measured from days 19 to 28. On days 21 (all supplements provided) and 30 (only daily supplements provided; day immediately prior to supplementation for 5D and 10D treatments) ruminal fluid was collected for ruminal pH, ammonia-N (NH3), volatile fatty acids (VFA), and determination of ruminal fermentation variables. Forage and total DM, organic matter (OM), and nitrogen (N) intake increased with supplementation (P ≤ 0.04). However, a linear effect of SF × amount of supplement interaction was observed for forage and total DM, OM, and N intake (P ≤ 0.04), with each variable decreasing as SF decreased, but the decrease being greater with F vs. H. Apparent total tract DM, OM, and neutral detergent fiber digestibility was not affected by supplementation or amount of supplement provided (P ≥ 0.10). In contrast, N digestibility increased with supplementation and for F vs. H (P < 0.01). Digestibility of DM, OM, and N increased linearly as SF decreased (P ≤ 0.03). When all supplements were provided, ruminal NH3, total VFA, and molar proportions of all individual VFA increased with supplementation (P ≤ 0.04), whereas acetate:propionate ratio decreased (P < 0.01). When only daily supplements were provided, none of the aforementioned fermentation parameters were affected (P ≥ 0.09). In summary, reducing the amount of supplemental CP provided to ruminants consuming low-quality forages, when supplementation intervals are >5 d, can be a management tool to maintain acceptable levels of DMI, nutrient digestibility, and ruminal fermentation while reducing supplementation cost.

Ovarian steroids play an important role in increasing plasma volume in pregnant females and preparing the uterus for implantation. We hypothesized that a short duration of increased estradiol-17β (E2) would increase plasma volume and uterine cell proliferation in ovariectomized ewes. Adult non-pregnant Romanov ewes (n = 15) were ovariectomized. After ovariectomy, ewes were individually housed and were offered water at ad libitum intake and were fed a pelleted diet at maintenance once daily according to body weight. After at least 30 days post-ovariectomy ewes were fasted and received an implant placed in the axillary region that contained 100 mg of E2 (E2; n = 8) or a sham implant with no E2 (CON, n = 7). After 24 h, ewes were weighed prior to plasma volume measurement procedures. Plasma volume was determined using the Evans blue dye method. Blood samples were taken at 0 (pre dye injection), 5, 10, 15, 20, 25, 30, 40, 50 and 60 min after dye injection. After the final blood collection, ewes were euthanized with an overdose of sodium pentabarbital and uterine weights were recorded. Uterine cross-sections were fixed in formalin for immunohistochemical localization of Ki67 (a marker of proliferating cells) followed by image generation of luminal epithelium and endometrial stroma (5 areas each/tissue section) and analysis to determine the proportion of proliferating cells. Plasma volume tended to be greater in E2 vs CON (2.75 ± 0.11 vs. 2.54 ± 0.12 L, P = 0.07) and uterine weights were greater in E2 vs CON (27.25 ± 2.35 vs. 17.35 ± 2.51 g, P 0.01). Water intake after implant placement was similar in E2 and CON (3.85 vs. 4.87 ± 0.67 L; P = 0.28). Cell proliferation in the luminal epithelium was greater in E2 vs CON (6.55 vs. 1.2 ± 1.75%, P = 0.02) and stromal cells tended to be greater in E2 vs CON (0.59 vs 0.37 ± 0.06%, P = 0.07). Our results demonstrate that E2-treatment tends to increase plasma volume acutely and increases uterine cell proliferation in ewes.

As cannabinoid production continues to increase, there is increasing interest in feeding byproducts of industrial hemp production to livestock. An experiment using crossbred heifers (n = 31; initial BW= 494 kg, SE = 10) was conducted to determine the effects of feeding hempseed cake in a corn-based finishing diet (10% forage) formulated to meet or exceed ruminally degradable and metabolizable protein requirements on growth, performance, carcass characteristics, and feeding behavior. Heifers were assigned randomly to one of two treatments: 1.) diet containing 20% dried distillers grains plus solubles (CON, n = 16), or 2.) diet containing 20% hempseed cake (HEMP, n = 15) on a dry-matter basis. Cattle were housed in two pens, had ad-libitum access to feed and water, and individual intakes and feeding behavior were captured using the Insentec BV feeding system across the feeding period (111 d). Final BW was not different (P = 0.28) between CON (696 kg, SE = 12) and HEMP (683 kg, SE = 12) heifers. Dry matter intake was not different between treatments (P = 0.99), while CON cattle had improved ADG and feed efficiency (G:F; P ≤ 0.04) compared to HEMP cattle. Carcass characteristics were not different (P ≥ 0.20) between treatments for all parameters measured. Control and HEMP cattle were not different (P ≥ 0.34) for number of meals, time spent eating, number of visits to the bunk per day, meal size, or eating rate. Feeding hempseed cake reduced ADG and G:F while having no effect on other performance measures, carcass characteristics, or feeding behavior. Overall, these data suggest hempseed cake could be a viable alternative feed source for ruminants depending on availability and cost. Further understanding of hempseed cakes’ nutrient utilization is critical to determining this products viability as a feedstuff for cattle.

To determine the effects of maternal nutrient restriction and re-alimentation on the fetal liver proteome, 48 pregnant ewes with singletons were fed a control diet [100% National Research Council (NRC) requirements (CON)] starting at the beginning of gestation. On day 50 of gestation, a subset of ewes were fed either CON or 60% NRC requirements (RES). A subset of ewes were euthanized at day 90 of gestation (n = 7/treatment), and fetal liver samples collected. Remaining ewes were maintained on the current diet (CON-CON, n=6; RES-RES, n = 7) or switched to alternative diet (CON-RES, RES-CON; n=7/treatment). On day 130 of gestation, remaining ewes were euthanized, and fetal samples collected. Fetal liver proteins were extracted, digested by trypsin and subjected to multiplexed, label-based quantitative mass spectrometry analysis integrating Tandem Mass Tags. Proteins were identified and quantified using Proteome Discoverer (v2.5, Thermo Scientific) and differential abundance analysis was performed using ANOVA and post hoc Tukey’s HSD test. Hierarchal clustering analysis showed clustering of treatments by day of gestation. However, differences were also observed between treatments. At day 90 of gestation, 23 proteins were differentially expressed in RES compared with CON among which glycyl tRNA synthetase and pyruvate carboxylase were increased 12% and 10%, respectively (P < 0.03). At day 130 of gestation, 24, 5, and 71 proteins were differentially expressed in CON-RES, RES-CON, and RES-RES, respectively, compared with CON-CON. Carnosine dipeptidase 2 was decreased 7% in CON-RES and rho associated protein kinase and glycogen synthase 2 were increased 20% and 26% in RES-CON and RES-RES, respectively, compared with CON-CON (P < 0.04). These results indicate that nutrient restriction during mid- and late-gestation impacts expression of proteins involved in gluconeogenesis, glycogenesis, and the formation of carnosine, an integral molecule in beta-oxidation, and that re-alimentation alters proteins involved in cell migration pathways. Supported by USDA-AFRI grants 2016-67016-24884 and 2017-67016-26568.

Sixty cows of varying frame scores (FS; 5.17 ± 1.38) were used to examine relationships between body size [BW, FS, and body volume (V)] and cow efficiency. Dry matter intake (DMI) and BW change were monitored over 64 days starting 1 month before bull turnout. Cows were fed a forage-based diet and DMI monitored using the Insentec system. Average BW (ABW; 662 ± 93.3 kg) was calculated by averaging 2-d beginning and end BW. Measurements (body length, hip height, hip width, and heart, mid, and flank girth) were collected at the beginning and end of the experiment and average V (628 ± 96.4 L) calculated. Calf BW was recorded at weaning (WW). Pearson partial correlations between body size characteristics and efficiency measures were determined using GLM (SAS) and the MANOVA/PRINTE statement. There was positive correlation (P < 0.001; r = 0.84, 0.74, 0.81) between DMI (kg) and ABW, FS, and V. There was a tendency for negative correlation (P = 0.08, 0.09; r = -0.24, -0.23) between DMI (% of BW) and ABW and V. There was positive correlation (P ≤ 0.05; r = 0.33, 0.28, 0.26) between WW (kg) and negative correlation (P < 0.001; r = -0.63, -0.57, -0.65) between WW (% of ABW) and ABW, FS, and V. There was positive correlation (P = 0.04; r = 0.26) between calf ADG and ABW, and a tendency for positive correlation (P = 0.09; r = 0.23) between calf ADG to weaning and FS. The observed correlations suggest that larger cows consume more kg of feed and wean heavier calves with greater ADG to weaning, whereas smaller cows tend to consume more feed as a percentage of BW and wean a greater percentage of cow BW. Further research is needed on the complex relationship between cow size and efficiency.

To examine the effects of maternal nutrient restriction on net uteroplacental flux during mid-gestation, 14 singleton ewes (48.2 ± 4.0 kg body weight) were fed 100% (control; CON; n = 7) or 60% of nutrient requirements (restricted; RES; n = 7) from day 50–90 (mid-gestation). On day 90, uteroplacental blood flow was measured via Doppler ultrasonography and blood samples were collected from the femoral artery, uterine vein, umbilical artery, and umbilical vein. Blood vessel glucose and amino acids (AA) concentrations were measured and arterial-venous (uterine, AV; fetal, va) differences and net fluxes were calculated. Data were analyzed using the GLM procedure of SAS for effects of treatment. Nutrient restriction during mid-gestation did not influence (P ≥ 0.17) uterine or umbilical blood flows. Uterine AV and fetal va differences of total, essential, and nonessential AA were not influenced (P > 0.10) by nutrient restriction. Nutrient restriction decreased (P ≤ 0.05) uterine and uteroplacental release of total AA and tended to decrease (P = 0.07) total AA uptake by the fetus. Uteroplacental release and fetal uptake of essential AA were decreased (P = 0.03) with RES by 53.4% and 45%, respectively. Uterine and uteroplacental release of nonessential AA were decreased (P = 0.03) with RES but, fetal uptake was not affected (P = 0.14). Nutrient restriction decreased (P ≤ 0.04) fetal uptake of methionine, phenylalanine, threonine, and valine and tended to decrease (P ≤ 0.10) fetal uptake of isoleucine, leucine, and tryptophan. Umbilical artery glucose concentrations were 32% lesser (P = 0.01) with RES and RES tended to increase (P = 0.08) fetal glucose uptake. Nutrient restriction during mid-gestation altered uteroplacental and fetal flux of AA in the current study. The results may indicate that fetal metabolism shifts to adapt to reduced AA supply which results in greater glucose utilization.

To determine the influence of maternal nutrient restriction and rumen-protected arginine supplementation on post-ruminal digestive enzyme activity in lambs, 31 multiparous, Rambouillet ewes were allocated to one of three dietary treatments at 54 d of gestation. Dietary treatments were 100% of nutrient requirements (control, CON; n = 11), 60% of control (restricted, RES; n = 10), or RES plus 180 mg rumen-protected arginine•kg BW(−1)•d(−1) (RES-ARG; n = 10). Immediately after parturition, lambs were removed from dams and reared independently. Milk-replacer and alfalfa hay + creep feed were offered for ad libitum intake. At day 54 of age, lambs were slaughtered and the pancreas and small intestine were collected. Pancreatic (α-amylase and trypsin) and jejunal (maltase, glucoamylase, sucrase, isomaltase, and lactase) digestive enzyme activities were assayed. Data were analyzed using the GLM procedure of SAS for effects of treatment. Contrast statements were used to determine differences between means for effects of restriction (CON vs. RES and RES-ARG) and rumen-protected arginine supplementation (RES vs. RES-ARG). There was no influence (P ≥ 0.15) of maternal nutrient restriction or rumen-protected arginine supplementation on pancreatic or jejunal protein concentrations. No treatment effects were observed (P ≥ 0.12) for enzymes involved in starch digestion including pancreatic α-amylase and jejunal maltase, glucoamylase, and isomaltase. Sucrase activity was undetected in the jejunum of lambs across all treatments. Maternal nutrient restriction tended to increase (P = 0.08) pancreatic trypsin activity per gram protein in lambs. Lactase activity per gram protein in the jejunum of lambs tended to decrease (P = 0.09) with maternal nutrient restriction. Rumen-protected arginine supplementation to gestating ewes did not influence (P ≥ 0.19) digestive enzyme activities of lamb offspring. These data suggest that maternal nutrient restriction and rumen-protected arginine supplementation have minimal effects on digestive enzyme activity in offspring.

Our objective was to conduct a systematic literature review and collate data to run a meta-regression on the effect of protein and energy restriction during the last third of gestation on offspring growth and carcass characteristics. The literature search was restricted to only using data from the last third of gestation in spring calving herds such that the last trimester coincided with winter months. Additionally, the search was limited to Bos taurus beef cattle and peer reviewed research articles; review articles and proceeding abstracts/papers were excluded. The search was conducted using the Web of Science. During this process we found contradictory results. As an example, some manuscripts indicate that energy and/or protein restriction during late gestation has a negative impact on offspring growth and/or carcass characteristics; however, there are also manuscripts that report no differences in similar growth and carcass variables (Table 1). Also, most of the studies reported no differences with maternal restriction on offspring body weight at calving and at weaning. One of the limitations in the data set is that most articles did not measure or report dry matter, net energy, or crude protein intake on the dam; therefore, making it difficult to predict the severity of maternal nutrient restriction and the effects on the offspring. Because of this gap in the literature, we suggest that net energy and crude protein intake should be reported in future studies to better determine the effects of maternal restriction during late gestation on offspring growth and carcass characteristics.