Abomasal infusion of arginine stimulates SCD and C/EBPß gene expression, and decreases CPT1ß gene expression in bovine adipose tissue independent of conjugated linoleic acid.

Based on previous research with bovine peadipocytes, we hypothesized that infusion of arginine into the abomasum of Angus steers stimulates stearoyl-CoA desaturase (SCD) gene expression in bovine subcutaneous (s.c.) adipose tissue, and that this would be attenuated by conjugated linoleic acid (CLA). Growing Angus steers were infused abomasally with L-arginine 50 g/day; n = 13; provided as L-arginine HCl) or L-alanine (isonitrogenous control, 100 g/day; n = 11) for 14 days. For the subsequent 14 days, half of the steers in each amino acid group were infused with CLA (100 g/day). Body weight gain and average daily gain were unaffected (P > 0.15) by infusion of arginine or CLA into the abomasum. The plasma concentrations of cis-9, trans-11 and trans-10, cis-12 CLA were increased CLA infusion (P = 0.001) and infusion of arginine increased plasma arginine (P = 0.01). Compared with day 0, fatty acid synthase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase enzyme activities in s.c. adipose tissue increased by day 14 in steers infused with either alanine or arginine (all P < 0.01). NADP-MDH activity was higher (P = 0.01) in steers infused with arginine than in steers infused with arginine plus CLA by day 28, but lipid synthesis in vitro from glucose and acetate was unaffected by infusion of either arginine or CLA (P > 0.40). By day 28, C/EBPß and SCD gene expression was higher, and CPT1ß gene expression was lower, in s.c. adipose tissue of steers infused with arginine than in steers infused with alanine (±CLA) (P = 0.05). CLA decreased adipose tissue oleic acid (18:1n-9) in alanine- or arginine-infused steers (P = 0.05), although CLA had no effect on SCD gene expression. The data indicate that supplemental arginine promotes adipogenic gene expression and may promote lipid accumulation in bovine adipose tissue. L-Arginine may beneficially improve beef quality for human consumption.

Acceptance and forage utilization responses of steers consuming low-quality forage and supplemented black soldier fly larvae as a novel feed.

As the insect-rearing industry scales in the United States and other developed nations, it has the potential to create multiple product streams (e.g., oil and protein-rich biomass) for existing markets. Black soldier fly larvae (BSFL; Hermetia illucens) has been identified as a potential livestock feed because it is not expected to compete in the human food sector and its production has a lesser environmental footprint than that of conventional feeds. Existing research on BSFL as feed focuses on full-fat BSFL for poultry and aquaculture. Therefore, the objective of our experiment was to evaluate the viability of defatted BSFL as an alternative protein source for beef cattle consuming forage. Procedures were approved by Texas State University IACUC (#7726). Two experiments were conducted using ruminally cannulated beef steers fed low-quality forage in 5 × 5 Latin squares. Experiment 1 assessed consumption of BSFL as a protein supplement and included five 5-d periods with 3-d for washout and 2-d for measurement of supplement intake and preference. There were five treatments delivered in addition to the basal forage: 100% soybean meal (SBM); 75% SBM/25% BSFL; 50% SBM/50% BSFL; 25% SBM/75% BSFL; and 100% BSFL. Supplement and forage intake did not differ between treatments (P ≥ 0.45) nor was there a treatment × day interaction (P ≥ 0.45). Experiment 2 evaluated the effect of BSFL supplementation on forage (5.3% crude protein) intake and digestion and included five 14-d periods with 8-d for treatment adaptation, 5-d for measurement of intake and digestion, and 1-d for determination of ruminal fermentation. There were four treatments of supplemental BSFL provided at graded N levels: 0, 50, 100, or 150 mg N/kg BW and one level of SBM at 100 mg N/kg BW. Increasing provision of BSFL linearly increased forage organic matter (OM) intake (P = 0.04), total OM intake (P < 0.01), total digestible OM intake (P < 0.01), dry matter digestibility (P = 0.01), and OM digestibility (P = 0.02). There were no significant differences (P ≥ 0.17) in intake or digestibility between levels of BSFL and SBM. Ultimately, defatted BSFL has potential to replace conventional feeds as a protein supplement without sacrificing forage utilization.

The insect-rearing industry, which involves the large-scale commercial growth of insects, is growing in developed nations, including the United States, to meet human food and animal feed demands. As the industry grows, there is increased interest in using black soldier fly larvae (BSFL) as a sustainable protein source for livestock feed. The goal of our research was to evaluate BSFL as an alternative protein supplement for beef cattle. We conducted two experiments using beef steers consuming hay. In the first experiment, we compared the amount of supplement that cattle would eat when BSFL was mixed with a traditional protein supplement, soybean meal (SBM), or offered to cattle alone. We did not observe statistical differences in supplement intake, indicating cattle will readily accept BSFL as feed. In the second experiment, we observed that hay intake and digestibility increased when increasing levels of protein were supplemented as BSFL. Importantly, BSFL performed comparably to SBM in measures of hay intake and digestibility. These findings suggest that BSFL may be able to replace conventional feeds as a protein supplement for beef cattle without compromising forage utilization, offering a sustainable alternative feed for the livestock industry.

An immersive field trip focused on beef production increases the sense of belonging in ethnoracial minority college students.

Sense of belonging is a student's sense of feeling accepted, valued, and included by others in their discipline. Imposter syndrome is self-perceived intellectual fraud in areas of success. Sense of belonging and imposter syndrome can influence behavior and well-being and are linked to academic and career outcomes. Our objective was to evaluate if a 5-d tour of the beef cattle industry changed college students' sense of belonging and imposter tendencies with a focus on ethnicity/race. Procedures involving human subjects were approved by the Texas State University (TXST) IRB (#8309). Students from TXST and Texas A&M University (TAMU) attended a beef cattle industry tour in the Texas Panhandle in May 2022. Identical pre- and post-tests were administered immediately before and after the tour. Statistical analyses were conducted with SPSS v.26. Independent sample t-tests were used to evaluate the change from pre- to post-survey and one-way ANOVA was used to evaluate the effect of ethnicity/race. Students (n = 21) were mostly female (81%); attended TAMU (67%) or TXST (33%); and were White (52%), Hispanic (33%), or Black (14%). "Hispanic" and "Black" were combined as a single variable to analyze differences between White and ethnoracial minority students. Before the tour, there was a difference (P = 0.05) in sense of belonging in agriculture between White (4.33 ± 0.16) and ethnoracial minority (3.73 ± 0.23) students such that White students had stronger belonging. There was no change (P = 0.55) in White students' sense of belonging as a result of the tour, from 4.33 ± 0.16 to 4.39 ± 0.44. However, there was a change (P ≤ 0.01) in ethnoracial minority students' sense of belonging, from 3.73 ± 0.23 to 4.37 ± 0.27. There was no change (P = 0.36) in imposter tendencies from the pre-test (58.76 ± 2.46) to the post-test (60.52 ± 2.79). Ultimately, participating in the tour increased ethnoracial minority, but not White, students' sense of belonging and did not impact imposter syndrome tendencies across or within ethnicity/race. One benefit of implementing experiential learning opportunities in dynamic social environments is the potential to improve students' sense of belonging, especially in disciplines and careers where ethnoracial minority people are underrepresented.

Evaluation of an Oral Supplemental Cannabidiol Product for Acceptability and Performance in Mature Horses.

Thirty stock type geldings (15 ± 3 years; 556 ± 63 kg BW) were used in a randomized complete design over 28 days to determine the influence of cannabidiol (CBD) oil supplementation levels on body weight, body condition, and blood chemistry. Horses were randomly assigned to one of three dietary treatments (n = 10 per treatment) formulated with canola oil to provide 1.50 mg CBD/kg BW (TRTA), 0.75 mg CBD/kg BW (TRTB), or 0.00 mg CBD/kg BW (canola oil; CTRL). Treatments were top-dressed onto concentrate and individually administered twice daily. Horses were maintained in adjacent dry lots and received coastal bermudagrass hay ad libitum. Body weight and body condition scores (BCS) were obtained every 14 days. On day 0 and 28, blood was collected via jugular venipuncture and serum was harvested to perform a blood chemistry panel and drugs of abuse screening at the Texas Veterinary Medical Diagnostic Laboratory. Data were analyzed using PROC MIXED of SAS (v9.4), and the model included treatment, time, and the treatment × time interaction, and linear and quadratic orthogonal polynomial contrasts to partition sum of squares. Analysis of composited treatment samples revealed lower CBD concentrations than indicated from initial testing by the manufacturer (0.13 mg CBD/kg in TRTA; 0.12 mg CBD/kg in TRTB). At this level of supplementation, canola-based CBD oil was well-accepted by mature horses, banned substances were not detectable in blood, and blood chemistry parameters were not adversely affected as a result of supplementation. More research is warranted to describe the discrepancy between formulated levels compared to tested levels of CBD in the canola-based supplement.

Texas panhandle beef production tour, a high-impact compressed course in animal science.

Many animal science students have little exposure to working livestock production systems prior to college. As such, they can lack insight into day-to-day challenges and rationale behind decision making in these systems, opening the door for the adoption of misconceptions frequently promoted in the popular press. In addition, students identify a lack of first-hand knowledge and experience in the industry as a challenge to their educational success. Field trips stimulate interest and motivation, provide context for learning, and influence long-term career goals, but are underutilized in higher education. The potential impact of such experiences prompted the creation of the Texas Panhandle Beef Production Tour, a 2-credit hour compressed course. Students on this tour visited beef production sites in the Texas Panhandle ranging from cow-calf operations, to feedlots and packing plants. To cement learning through reflection, students responded to a series of questions before, during, and after visiting these sites to probe preconceptions, observations, and outcomes of the experience. We performed a retroactive qualitative evaluation of these reflections (n = 22) to determine cogent themes. Emergent themes included surprise at the intensive systems of data collection and management and the level of technology used at each site. Cattle were calmer and more comfortable than expected at the feedlots and packing plants. Students expressed new appreciation and understanding of course material and a desire to share their insights with others after completing the tour. Finally, participants gained a broader view of industry opportunities and returned with renewed motivation to pursue additional hands-on opportunities. Participation in this course provided valuable insight into the livestock production industry and motivated students to explore new career options and address their own preconceptions of the industry through independent inquiry. The creation of similar courses may be useful to address misconceptions, create personal connections with course material, and broaden career interests in animal science students.

Evaluation of Black Soldier Fly larvae (Hermetia illucens) as a protein supplement for beef steers consuming low-quality forage.

Black Soldier Fly larvae (BSFL; Hermetia illucens) has been the focus of recent feeding trials in poultry, swine, and fish; however, in vivo research has not yet been conducted in cattle. Accordingly, a study was conducted to evaluate the effects of BSFL as a protein supplement in beef steers. Six steers (603 ± 20 kg of BW, n = 3 and 404 ± 17 kg of BW, n = 3) consuming King Ranch bluestem hay (6.55% dry matter [DM] crude protein [CP]) ad libitum were used in two simultaneous 3 × 3 Latin squares. Steers were provided one of three treatments each period: 1) a control with no supplement (CON), 2) a supplement comprised of conventional feed ingredients with whole cottonseed and soybean meal as the main protein sources (CONV), and 3) a supplement with BSFL as the main protein source (BSFL). Three 14-d periods were conducted with 8 d to adapt to treatments, 5 d to measure intake and digestion, and 1 d to complete a ruminal fermentation profile. DM, organic matter (OM), CP, neutral detergent fiber (NDF), and acid detergent insoluble ash were determined in forage, supplement, ort, and fecal samples. Protein supplementation as CONV or BSFL stimulated forage OM intake (P ≤ 0.01) relative to CON with a trend for a difference (P = 0.08) between the supplements such that CONV steers consumed more FOMI than BSFL steers. Treatment affected total digestible OM intake (TDOMI; P ≤ 0.01); TDOMI for CON steers was 47.5 g/kg metabolic body weight (MBW) which was significantly less (P ≤ 0.01) than that of CONV or BSFL steers. Steers supplemented with CONV consumed significantly more TDOMI than BSFL steers (P = 0.05; 62.2 vs. 60.1 g/kg MBW, respectively). Treatment did not significantly affect digestibility of DM, OM, or NDF (P > 0.32). There was also not a significant effect (P ≥ 0.17) of treatment on ruminal ammonia-N, total volatile fatty acids, or ruminal pH. Overall, these data indicate that BSFL may be an effective protein supplement for beef cattle consuming low-quality forage.

Ursids evolved early and continuously to be low-protein macronutrient omnivores.

The eight species of bears world-wide consume a wide variety of diets. Some are specialists with extensive anatomical and physiological adaptations necessary to exploit specific foods or environments [e.g., polar bears (Ursus maritimus), giant pandas (Ailuropoda melanoleuca), and sloth bears (Melursus ursinus)], while the rest are generalists. Even though ursids evolved from a high-protein carnivore, we hypothesized that all have become low-protein macronutrient omnivores. While this dietary strategy has already been described for polar bears and brown bears (Ursus arctos), a recent study on giant pandas suggested their macronutrient selection was that of the ancestral high-protein carnivore. Consumption of diets with inappropriate macronutrient profiles has been associated with increased energy expenditure, ill health, failed reproduction, and premature death. Consequently, we conducted feeding and preference trials with giant pandas and sloth bears, a termite and ant-feeding specialist. Both giant pandas and sloth bears branched off from the ursid lineage a million or more years before polar bears and brown bears. We found that giant pandas are low-protein, high-carbohydrate omnivores, whereas sloth bears are low-protein, high-fat omnivores. The preference for low protein diets apparently occurred early in the evolution of ursids and may have been critical to their world-wide spread.

Effects of crude protein content on intake and digestion of coastal bermudagrass hay by horses.

This study was conducted to determine the effects of forage crude protein (CP) level on intake and digestion of Coastal bermudagrass hay by horses. Four cecally fistulated geldings were used in a 4 × 4 Latin square design with four treatments and four periods. Horses were fed one of four Coastal bermudagrass hays consisting of 7%, 10%, 13%, or 16% CP during each of the four 15-d periods. Intake and apparent digestibility were determined for each horse at the end of each period by total fecal collection. In addition, cecal fluid and blood samples were collected on the last day of each period for the determination of cecal ammonia, cecal pH, plasma urea nitrogen (PUN), and plasma glucose concentrations. Data were analyzed using PROC MIXED of SAS. CP concentration of Coastal bermudagrass hay influenced equine intake and digestion. Increasing CP concentration linearly increased digestible organic matter intake (DOMI) from 3.79 to 5.98 kg/d for 7% and 16% CP hay, respectively (P = 0.04). Furthermore, as the forage CP level increased, CP intake increased linearly (P < 0.01). The forage CP level had no effect on forage dry matter intake. Quadratic effects (P ≤ 0.05) were observed for forage OM, neutral detergent fiber, acid detergent fiber, and digestible energy. Overall digestibility was lowest for the 7% CP hay and highest for the 10% CP hay. Cecal pH remained above 6.62 irrespective of treatment and time, indicating that cecal pH was suitable for microbial growth. As the forage CP level increased, cecal ammonia concentration increased linearly from 0.03 mM for the 7% to 1.74 mM for the 16% CP hay (P < 0.01). Concentration of plasma glucose also linearly increased (P = 0.04) from 68.77 to 73.68 mg/dL as CP concentration increased from 7% to 16% CP. PUN exhibited a quadratic effect as concentration increased (P < 0.01) from 4.34 to 5.61 mM for the 7% and 16% CP hays, respectively. Overall, the 10% CP hay had the highest digestibility due to its higher OM digestion. As forage OMI increased, digestible OM increased until physiological capacity for digestion is exceeded. At that point, digestion will decline with the decrease in OMI, explaining the lower digestion for other forages fed.

The effects of signalment, diet, geographic location, season, and colitis associated with antimicrobial use or Salmonella infection on the fecal microbiome of horses.

BACKGROUND: The fecal microbiome of healthy horses may be influenced by signalment, diet, environmental factors, and disease. OBJECTIVES: To assess the effects of age, breed, sex, geographic location, season, diet, and colitis caused by antibiotic use (antimicrobial-associated diarrhea [AAD]) and Salmonella infection on fecal microbiota. ANIMALS: Healthy horses (n = 80) were sampled from nonhospital environments across multiple geographical locations in the United States. Horses with AAD (n = 14) were defined as those that developed diarrhea secondary to antimicrobial use. Horses with Salmonella infection (n = 12) were presented with spontaneous onset of colitis and subsequently tested positive on Salmonella quantitative polymerase chain reaction. All horses were >1 year of age and stratified by a dietary scale that included forages (pasture and hay) and concentrates grouped by percentage of fiber and amount. METHODS: Illumina sequencing of 16S rRNA genes was performed on fecal DNA. RESULTS: Healthy horses fed higher amounts of grain clustered separately from those fed lower amounts of grain (analysis of similarities [ANOSIM], R = 0.356-0.385, Q = 0.002). Horses with AAD and Salmonella had decreased richness and evenness compared to healthy horses (P < .05). Univariable analysis of the 3 groups identified increases in Bacteroidetes (Q = 0.002) and Protebacteria (Q = 0.001) and decreases in Verrucomicrobia (Q = 0.001) in AAD horses whereas Salmonella horses had less Firmicutes (Q = 0.001) when compared to healthy horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Although the amount of grain in the diet had some impact on the fecal microbiome, colitis had a significantly larger influence. Horses with ADD have a more severe dysbiosis than do horses with Salmonella.

Maternal nutrient restriction in late pregnancy programs postnatal metabolism and pituitary development in beef heifers.

Maternal undernutrition during pregnancy followed by ad libitum access to nutrients during postnatal life induces postnatal metabolic disruptions in multiple species. Therefore, an experiment was conducted to evaluate postnatal growth, metabolism, and development of beef heifers exposed to late gestation maternal nutrient restriction. Pregnancies were generated via transfer of in vitro embryos produced using X-bearing sperm from a single Angus sire. Pregnant dams were randomly assigned to receive either 100% (control; n = 9) or 70% (restricted; n = 9) of their total energy requirements from gestational day 158 to parturition. From post-natal day (PND) 301 until slaughter (PND485), heifers were individually fed ad libitum in a Calan gate facility. Calves from restricted dams were lighter than controls at birth (P<0.05) through PND70 (P<0.05) with no difference in body weight from PND105 through PND485 (P>0.10). To assess pancreatic function, glucose tolerance tests were performed on PND315 and PND482 and a diet effect was seen with glucose area under the curve being greater (P<0.05) in calves born to restricted dams compared to controls. At slaughter, total internal fat was greater (P<0.05) in heifers born to restricted dams, while whole pituitary weight was lighter (P<0.05). Heifers from restricted dams had fewer growth hormone-positive cells (somatotrophs) compared to controls (P<0.05). Results demonstrate an impaired ability to clear peripheral glucose in heifers born to restricted dams leading to increased deposition of internal fat. A reduction in the number of somatotrophs may contribute to the adipogenic phenotype of heifers born to restricted dams due to growth hormone's known anabolic roles in growth, lipolysis, and pancreatic islet function.

Rumen bacterial diversity dynamics associated with changing from bermudagrass hay to grazed winter wheat diets.

Rumen bacterial communities in forage-fed and grazing cattle continually adapt to a wide range of changing dietary composition, nutrient density, and environmental conditions. We hypothesized that very distinct community assemblages would develop between the fiber and liquid fractions of rumen contents in animals transitioned from bermudagrass hay diet to a grazed wheat diet. To address this hypothesis, we designed an experiment utilizing a 16S-based bTEFAP pyrosequencing technique to characterize and elucidate changes in bacterial diversity among the fiber and liquid rumen fractions and whole rumen contents of 14 (Angus x Hereford) ruminally cannulated steers sequentially fed bermudagrass hay (Cynodon dactylon; 34 days) and grazing wheat forage (28 days). Bermudagrass hay was a conserved C4 perennial grass lower in protein and higher in fiber (11% and 67%, respectively) content than grazed winter wheat (Triticum aestivum), a C3 annual grass with higher protein (20%) and a large (66%) soluble fraction.Significant differences in the OTU estimates (Chao1, Ace,and Rarefaction) were detected between fractions of both diets, with bermudagrass hay supporting greater diversity than wheat forage. Sequences were compared with a 16S database using BLASTn and assigned sequences to respective genera and genera-like units based on the similarity value to known sequences in the database. Predominant genera were Prevotella (up to 33%) and Rikenella-like (upto 28%) genera on the bermudagrass diet and Prevotella (upto 56%) genus on the wheat diet irrespective of the fractions. Principle component analyses accounted for over 95% of variation in 16S estimated bacterial community composition in all three fractions and clearly differentiated communities associated with each diet. Overall, bermudagrass hay diets clustered more clearly than wheat diets.These data are the first to explore bacterial diversity dynamics in a common population of animals in response to contrasting grass forage diets.

Effects of monensin inclusion and level of intake in limit-feeding strategies for beef cows.

A study was conducted to evaluate the effects of intake management and ionophore inclusion on diet utilization under managed intake conditions in beef cattle. Two experiments utilized common diets fed at 120% (H) or 80% (L) of maintenance with either 0 or 200 mg/d monensin in a factorial arrangement. Forty cows were fed for 56 d (Exp. 1) to evaluate effects on diet utilization and energy retention; diets were fed to 16 ruminally cannulated steers (Exp. 2) to determine effects on digestion, energy value, and ruminal fermentation. Cows fed H had greater body weight (BW) gain (P < 0.01) and retained energy (RE; P < 0.01), although estimated heat production was also greater (P < 0.01). Monensin had limited effects on overall BW gain (P = 0.97). Monensin had no effect on RE (P = 0.94) or calculated heat energy (HE; P = 0.53) despite effects on diet utilization observed in steers. In steers, L increased (P < 0.01) digestion of dry matter, organic matter, acid detergent fiber, and gross energy (GE) and reduced (P < 0.01) passage rate; monensin did not affect digestion (P > 0.15) but did reduce passage rate (P < 0.03). Monensin lowered (P < 0.01) acetate:propionate ratio and increased (P < 0.05) ruminal pH. Monensin did not alter feed required for maintenance; however, limit-feeding reduced apparent daily maintenance requirement to 62.85 kcal/kg BW0.75, a 26% reduction from model-predicted values.

The effects of the forage-to-concentrate ratio on the conversion of digestible energy to metabolizable energy in growing beef steers.

Metabolizable energy (ME) is calculated from digestible energy (DE) using a constant conversion factor of 0.82. Methane and urine energy losses vary across diets and dry matter intake (DMI), suggesting that a static conversion factor fails to describe the biology. To quantify the effects of the forage-to-concentrate ratio (F:C) on the efficiency of conversion of DE to ME, 10 Angus steers were used in a 5 × 5 replicated Latin square. Dry-rolled corn was included in experimental diets at 0%, 22.5%, 45.0%, 67.5%, and 83.8% on a dry matter (DM) basis, resulting in a high F:C (HF:C), intermediate F:C (IF:C), equal F:C (EF:C), low F:C (LF:C), and a very low F:C (VLF:C), respectively. Each experimental period consisted of a 23-d diet adaption followed by 5 d of total fecal and urine collections and a 24-h gas exchange collection. Contrasts were used to test the linear and quadratic effects of the F:C. There was a tendency (P = 0.06) for DMI to increase linearly as F:C decreased. As a result, gross energy intake (GEI) increased linearly (P = 0.04) as F:C decreased. Fecal energy loss expressed as Mcal/d (P = 0.02) or as a proportion of GEI (P < 0.01) decreased as F:C decreased, such that DE (Mcal/d and Mcal/kg) increased linearly (P < 0.01) as F:C decreased. As a proportion of GEI, urine energy decreased linearly (P = 0.03) as F:C decreased. Methane energy loss as a proportion of GEI responded quadratically (P < 0.01), increasing from HF:C to IF:C then decreasing thereafter. The efficiency of DE to ME conversion increased quadratically (P < 0.01) as F:C decreased, ranging from 0.86 to 0.92. Heat production (Mcal) increased linearly (P < 0.04) as F:C decreased but was not different as a proportion of GEI (P ≥ 0.22). As a proportion of GEI, retained energy responded quadratically (P = 0.03), decreasing from HF:C to IF:C and increasing thereafter. DM, organic matter, and neutral detergent fiber digestibility increased linearly (P < 0.01) and starch digestibility decreased linearly (P < 0.01) as the F:C decreased. Total N retained tended to increase linearly as the proportion of concentrate increased in the diet (P = 0.09). In conclusion, the efficiency of conversion of DE to ME increased with decreasing F:C due to decreasing methane and urine energy loss. The relationship between DE and ME is not static, especially when differing F:C.

Technical note: Relationship between placentome location and gene expression in bovine pregnancy.

A novel, non-terminal surgical procedure to remove a single placentome from the pregnant ewe for gene expression and histological analyses was recently developed in our laboratory. This technique allows for evaluation of nutritional insults on placental development at more than one stage of gestation using a single animal. Early attempts to develop a similar technique in cattle were met with complications due to inaccessibility of the gravid uterine horn because of its location and mass. One alternative is to collect a placentome from the contralateral uterine horn; however, the question remains as to whether gene expression varies among placentomes based on location relative to the fetus. Pregnant heifers were maintained on forage during early gestation and later moved into pens with a Calan gate system (American Calan, Northwood, NH). On gestational day (GD) 158, five heifers were assigned to receive a hay-based diet formulated to meet 100% of NRC requirements, and five heifers were fed 70% of NRC requirements until necropsy on GD244. At necropsy, a single representative placentome was selected for analysis from the antimesometrial side: (1) of the gravid uterine horn central to the amnion, (2) over the allantois immediately adjacent to the amnion, (3) in the tip of the gravid uterine horn, and (4) in the tip of the contralateral uterine horn. Mean placentome weight was greater (P < 0.05) for locations central to the amnion and allantois compared to locations within the tips of the ipsilateral and contralateral horns, respectively. Gene expression for angiogenic factors (FGF2, ODC1, VEGFA, and FLT1), nutrient transporters (SLC7A1 and SLC2A1), and factors associated with hormone action (ESR1, IGF1, IGFBP3, CSH1, and PAG1) were unaffected (P > 0.05) by dietary treatment or location of the placentome. Results indicate that location of the placentome in relation to the fetus does not impact gene expression, enhancing the efficacy of nonterminal methodologies for sampling gene expression in placentomes.

Effects of diet type on nutrient utilization and energy balance in drylot heifers1.

Feeding cattle in intensified settings allows cow-calf producers to decrease their reliance on grazed forage and utilize alternative feedstuffs. During times of intense management, diet type may alter energy utilization. Fourteen pregnant MARC III heifers (405 ± 44 kg BW) were used in a 180 d experiment to determine effects of diet type on nutrient and energy utilization. Heifers were randomly assigned to one of two treatments, a forage diet (FOR; 2.10 Mcal metabolizable energy [ME]/kg; 95.75% forage) or a concentrate diet (CONC; 2.94 Mcal ME/kg; 71% concentrate), and individually fed to meet maintenance energy requirements (0.135 Mcal ME/kg BW0.75). The CONC diet contained dry-rolled corn, corn stalks (10.16 cm grind size), soybean meal, corn silage (approximately 45% corn grain; stored in a plastic bag), dicalcium phosphate, urea, and a premix pellet; FOR contained alfalfa hay (harvested at mid-bloom), corn silage, dicalcium phosphate, and a premix pellet. Measurements of energy intake and digestibility were measured over a 4-d period on days 116, 172, and 235 of gestation. Using portable headbox calorimeters, measurements of O2, CO2, and CH4 gases were collected over a period of 24 h. Data were analyzed in a completely randomized design with diet as fixed effect. Dry matter and organic matter digestibility were greater for CONC than FOR (P < 0.01). Intake of gross energy (GE) and digestible energy (DE) were greater for FOR (P < 0.01), but by design, ME intake was not different between treatments (P = 0.26). Energy lost as methane (% of GE intake) was not different between treatments (P = 0.49). The ratio of ME to DE was greater for CONC (86.8 vs. 82.8; P = 0.01) than FOR. Heat production relative to ME was not different between treatments (P = 0.85). Maternal tissue energy did not differ and was 1.2 Mcal/d for CONC and 0.9 Mcal/d for FOR (P = 0.73). Greater nitrogen (N) consumption was observed for FOR (192.2 g/d) than CONC (134.0 g/d; P < 0.01), and retained N was greater for FOR than CONC (P < 0.01) on days 116 and 235 of gestation. Neither concentrate-based or forage-based diets affected body condition score (P = 0.26). Heifers fed concentrate-based diets retained more energy in part because they had larger calves, but this energy was not recovered in maternal tissue.

Metabolic studies reveal that ruminal microbes of adult steers do not degrade rumen-protected or unprotected L-citrulline.

In vitro and in vivo experiments were conducted to determine the metabolism of rumen-protected or unprotected l-citrulline (Cit) plus l-glutamine (Gln) by ruminal microbes. In the in vitro experiment, whole ruminal fluid (3 mL, containing microorganisms) from steers was incubated at 37 ºC with 5 mM Cit plus 6 mM Gln (in a rumen-protected or unprotected form) for 0, 0.5, 2, or 4 h after which times 50 µL samples were collected for AA and ammonia analyses. In the in vivo experiment, at 0.5 h before and 0, 0.5, 1, 2, 4, and 6 h after cannulated adult steers consumed 0.56 kg dried-distillers' grain mixed with 70 g Cit plus 70 g Gln (in a rumen-protected or unprotected form), samples of ruminal fluid and jugular venous blood were obtained for AA analyses. Results from both in vitro and in vivo experiments demonstrated extensive hydrolysis of rumen-unprotected Gln into glutamate, but little degradation of the rumen-protected Gln or rumen-protected and unprotected Cit by ruminal microbes. Concentrations of Cit and arginine in the plasma of steers consuming rumen-protected or unprotected AA increased at 1 and 2 h after the meal, respectively, when compared with values at 0 h. Collectively, these novel findings indicate that ruminal microbes of adult steers do not degrade extracellular Cit in a rumen-protected or unprotected form. Our results refute the view that all dietary AAs are extensively catabolized by ruminal microorganisms and also have important implications for dietary supplementation with Cit to ruminants to enhance the concentration of arginine in their plasma and their productivity.

Influence of diet fortification on body composition and apparent digestion in mature horses consuming a low-quality forage.

Stock-type mares (498 ± 9 kg BW; 12 ± 7 yr) were used in a completely randomized design for 56 d to test the hypothesis that concentrate fortification improves apparent digestion and enhances lean mass over the topline. Horses were stratified by age, BW, and BCS and randomly assigned to either a custom pelleted concentrate (CON; n = 13), or an iso-caloric, iso-nitrogenous pellet that included amino acid fortification, complexed trace minerals, and fermentation metabolites (FORT; n = 10). Concentrate was offered at a total 0.75% BW/d (as-fed) twice daily, and diets were designed to meet or exceed maintenance requirements for mature horses. Horses had ad libitum access to Coastal bermudagrass hay (7.4% CP, 67% NDF, and 40% ADF). Every 14 d BW and BCS were recorded, and ultrasound images were captured every 28 d. longissimus dorsi area (LDA) and subcutaneous fat thickness (FT) were measured between the 12th and 13th ribs (12th/13th) and 17th and 18th ribs (17th/18th). Intramuscular fat at the 17th/18th ribs and rump fat-thickness were also obtained. Horses were dosed with 10 g/d of titanium dioxide (TiO2) for 14 d to estimate forage dry matter intake (DMI). To account for diurnal variation, fecal samples were collected twice daily at 12-h intervals during the last 4 days, advancing by 3 h each day to represent a 24-h period. Fecal samples were composited by horse and analyzed for TiO2 to estimate fecal output and acid detergent insoluble ash was used to calculate forage DMI. To evaluate body composition, horses were infused with a 0.12 g/kg BW deuterium oxide (D2O) on d 0 and 56. Body fat percentage (BF) was determined by quantifying D2O in plasma samples collected at pre- and 4-h postinfusion via mass spectrometry. All data were analyzed using PROC MIXED (SAS v9.4). The model contained a fixed effect of diet; horse (diet) was a random effect. Horses receiving FORT gained 17th/18th FT (P < 0.01) and increased 17th/18th LDA from d 0 to 56 (P < 0.01) while 17th/18th FT and LDA were unchanged in CON. Regardless of diet, BF estimated by D2O infusion increased in all horses from d 0 to 56 (P < 0.01). Average hay DMI was 2.1% BW, but did not differ between diets. In this study, concentrate fortification did not significantly (P ≥ 0.27) affect apparent digestion. In conclusion, concentrate fortification may promote greater muscle development along the posterior topline.

Evaluation of dietary trace mineral supplementation in young horses challenged with intra-articular lipopolysaccharide.

Sixteen weanling Quarter Horses (255 ± 22 kg) were utilized in a 56-d trial to evaluate the effects of trace mineral (TM) source on intra-articular inflammation following a single acute inflammatory insult. Horses were stratified by age, sex, and BW and then randomly assigned to dietary treatment: concentrate formulated with Zn, Mn, Cu, and Co as inorganic sources (CON; n = 8) or complexed TMs (CTM; n = 8). Added TM were formulated at iso-levels across treatments and intakes met or exceeded NRC requirements. Horses were offered 1.75% BW (as-fed) of treatment concentrate and 0.75% BW (as-fed) coastal Bermudagrass hay. Growth measurements were collected on days 0, 28, and 56, and plasma was collected biweekly for determination of Mn, Cu, Zn, and Co concentrations. On day 42, carpal joints were randomly assigned to receive injections of 0.5 ng lipopolysaccharide (LPS) or sterile lactated Ringer's solution (LRS; contralateral control). Synovial fluid was collected at preinjection hours (PIH) 0, and 6, 12, 24, 168, and 336 h post-injection and analyzed for TM concentration, prostaglandin E2 (PGE2), carboxypeptide of type II collagen (CPII), collagenase cleavage neopeptide (C2C), and aggrecan chondroitin sulfate 846 epitope (CS846). Data were analyzed using the MIXED procedure of SAS. Results showed a TM source × LPS × h effect for synovial fluid Co, Cu, and Se (P < 0.05); concentrations of TM peaked at hour 6 and decreased to preinjection values by hour 168 in both CON and CTM-LPS knees. A delayed peak was observed at hour 12 for CTM-LRS. Peak synovial fluid Cu and Se concentrations were higher in LPS knees, and Co was highest in CTM-LPS. A TM source × h interaction was observed for Zn (P < 0.05); concentrations peaked at hour 6 in CON vs. hour 12 for CTM. An LPS × h interaction was observed for Mn (P < 0.01); synovial concentration peaked at hour 6 in LPS knees compared with hour 24 in LRS. Synovial PGE2, C2C, CPII, and CS846 concentrations were greater with LPS (P ≤ 0.01), and C2C was greater (P < 0.01) in CTM compared with CON. Concentrations of CPII and PGE2 were unaffected by diet. A TM source × h × LPS interaction was observed for CS846 (P = 0.02). Concentrations of CS846 in CTM peaked at 12 h, whereas CON peaked at a lower concentration at 24 h (P < 0.05). Data indicate sufficient intake of a complexed TM source may support cartilage metabolism through increased aggrecan synthesis and type II collagen breakdown following an intra-articular LPS challenge in growing horses.

Effects of adding liquid lactose or molasses to pelleted swine diets on pellet quality and pig performance.

Two experiments were conducted to evaluate the effects of including liquid lactose (LL) and molasses (M) in swine diets on pellet quality and pig performance. In experiment 1, a total of 194 nursery pigs (DNA 241 × 600, initially 6.7 ± 0.4 kg at 27 d of age) were used in a 33-d experiment evaluating the effects of LL (SweetLac 63; Westway Feed Products, Tomball, TX) or cane molasses on nursery pig performance and pellet quality. Pelleted experimental diets were fed from d 0 to 21, and a common pelleted diet fed from d 21 to 33. Dietary treatments consisted of a control diet containing 19.1% total sugars from whey powder and whey permeate and experimental diets with a percentage of whey permeate replaced by either 5% or 10% LL or 9.4% cane molasses (5 LL, 10 LL, and 9.4 M, respectively). Hot pellet temperature and production rate decreased (P < 0.05) from the control to 9.4 M treatments with 5 LL and 10 LL having intermediate effects. Pellet durability index (PDI) increased (P < 0.05) in 5 LL, 10 LL, and 9.4 M, respectively. From d 0 to 7, pigs fed the 10 LL and 9.4 M treatment had the best G:F followed by the control and 5 LL treatments. From d 0 to 21, ADFI had a marginally significant improvement (P < 0.10) in pigs fed up to 10 LL in the diet. Fecal consistency scores at d 7 were also firmer (P < 0.05) in pigs fed 9.4 M compared with pigs fed the control or 5 LL treatments with pigs fed the 10 LL treatment being intermediate. There was no evidence for differences in fecal consistency scores for d 14. In experiment 2, a total of 289 finishing pigs (DNA 241 × 600; initially 53.5 ± 0.5 kg BW) were used in a 53-d experiment evaluating the effects of LL on pellet quality and finishing pig performance. Experimental diets were fed in pelleted form from d 0 to 53 divided into three phases. Dietary treatments were a corn-soybean meal control diet with 0%, 2.5%, 5%, and 7.5% LL added in the place of corn. PDI improved (linear, P < 0.01) with increasing inclusion of LL. There were no differences in ADG, ADFI, final BW, or carcass characteristics. Pigs fed diets with increasing levels of LL tended to have improved (quadratic, P = 0.070) G:F.

Effect of undegradable intake protein supplementation on urea kinetics and microbial use of recycled urea in steers consuming low-quality forage.

We evaluated the effect of undegradable intake protein (UIP) on urea kinetics and microbial incorporation of urea-N in ruminally and duodenally fistulated steers (n 4; 319 kg) provided ad libitum access to grass hay in a 4 x 4 Latin square. Casein was continuously infused abomasally in amounts of 0, 62, 124 and 186 mg N/kg body weight per d to simulate provision of UIP. Periods were 13 d long with 7 d for adaptation and 6 d for collection. Jugular infusion of [15N15N]urea followed by determination of urinary enrichment of [15N15N]urea and [14N15N]urea was used to measure urea kinetics. Forage and N intake increased (quadratic, P<0.02) with increasing UIP. Urea synthesis was 27.1, 49.9, 82.2 and 85.8 g urea-N/d for 0, 62, 124 and 186 diets, respectively (linear, P<0.01). The proportion of urea synthesis that entered the gastrointestinal tract was 0.96 for steers receiving no UIP and decreased linearly (P=0.05) to a low of 0.89 for steers receiving 186. The amount of urea entering the gastrointestinal tract was least for 0 (26.3) and increased (linear, P<0.01) to 48.7, 77.2 and 76.6 g urea-N/d for 62, 124 and 186 diets, respectively. Microbial incorporation of recycled urea-N increased quadratically (P=0.04) from 13.9 for 0 to 47.7 g N/d for 124. The proportion of microbial N derived from recycled urea increased (quadratic, P=0.05) from 0.31 to 0.58 between 0 and 124 and dropped to 0.44 for 186 mg N/kg body weight per d. UIP increased intake of hay and provided a N source for ruminal microbes via urea recycling.