Holstein Steers Research Articles

Alterations of rumen and fecal microbiome in growing beef and dairy steers fed rumen-protected Capsicum oleoresin.

The microbiome has been linked to animal health and productivity, and thus, modulating animal microbiomes is becoming of increasing interest. Antimicrobial growth promoters (AGP) were once a common technology used to modulate the microbiome, but regulation and consumer pressure have decreased AGP use in food animals. One alternative to antimicrobial growth promoters are phytotherapeutics, compounds derived from plants. Capsaicin is a compound from the Capsicum genus, which includes chili peppers. Capsaicin has antimicrobial properties and could be used to manipulate the gastrointestinal microbiome of cattle. Both the rumen and fecal microbiomes are essential to cattle health and production, and modulation of either microbiome can affect both cattle health and productivity. We hypothesized that the addition of rumen-protected capsaicin to the diet of cattle would alter the composition of the fecal microbiome, but not the rumen microbiome. To determine the impact of rumen-protected capsaicin in cattle, four Holstein and four Angus steers were fed rumen-protected Capsicum oleoresin at 0 (Control), 5, 10, or 15mg kg-1 diet dry matter. Cattle were fed in treatment groups in a 4 × 4 Latin Square design with a 21-d adaptation phase and a 7-d sample collection phase. Rumen samples were collected on day 22 at 0-, 2-, 6-, 12-, and 18-h post-feeding, and fecal swabs were collected on the last day of sample collection, day 28, within 1h of feeding. Sequencing data of the 16s rRNA gene was analyzed using the dada2 pipeline and taxa were assigned using the SILVA database. No differences were observed in alpha diversity among fecal or rumen samples for either breed (P > 0.08) and no difference between groups was detected for either breed in rumen samples or for Angus steers in fecal samples (P > 0.42). There was a difference in beta diversity between treatments in fecal samples of Holstein steers (P < 0.01), however, a pairwise comparison of the treatment groups suggests no difference between treatments after adjusting for multiple comparisons. Therefore, we were unable to observe substantial overall variation in the rumen or fecal microbiomes of steers due to increasing concentrations of rumen-protected capsaicin. We do, however, see a trend toward increased concentrations of capsaicin influencing the fecal microbiome structure of Holstein steers despite this lack of significance.

Supplemental effects of rumen-protected L-tryptophan at various levels on starch digestion, melatonin, and gastrointestinal hormones in Holstein steers

Supplemental effects of rumen-protected L-tryptophan at various levels on starch digestion, melatonin, and gastrointestinal hormones in Holstein steers

The impact of sire breed on feedlot performance and carcass characteristics of beef × Holstein steers.

Dairy herds are mating a portion of cows to beef cattle semen to create a value-added calf. Objectives of this study were to compare the feedlot performance and carcass characteristics of beef × Holstein steers by breed when sires represented bulls with commercially available semen. Three groups of single-born, male calves (n = 262) born to Holstein dams on 10 Pennsylvania dairies were sourced during 3 yr. Steers were sired by seven beef breeds: Angus, Charolais, Limousin, Hereford, Red Angus, Simmental, and Wagyu. Steers were picked up within a week of age and raised at two preweaned calf facilities until weaning (8 ± 1wk of age) under similar health and management protocols. Steers were then transported to a commercial calf growing facility where they were managed as a single group until 10 ± 2 mo of age when they were moved to be finished at the Pennsylvania Department of Agriculture's Livestock Evaluation Center feedlot. Groups of steers were selected for slaughter based on body weight. Carcass characteristics were evaluated by trained personnel and a three-rib section of the longissimus muscle (LM) was collected from each carcass for Warner-Bratzler shear force (WBSF) evaluation and intramuscular fat determination. Steers sired by all sire breeds except for Limousin had greater average daily gain (ADG; 1.62 to 1.76kg/d) than Wagyu × Holstein steers (1.39kg/d; P < 0.05). Angus-sired steers had an 8.6% greater ADG than Red Angus-sired steers (P < 0.05). Angus, Charolais (1.73kg/d), and Simmental-sired steers (1.68kg/d) also had greater ADG than Limousin-sired steers (1.55kg/d; P < 0.05). Wagyu × Holstein steers spent 5 to 26 more days on feed (P < 0.05) than Limousin × Holstein, Simmental × Holstein, Angus × Holstein, and Charolais × Holstein steers. Angus and Charolais-sired steers were also on feed for 19 and 21 d fewer, respectively, than Limousin-sired steers (P < 0.05). Red Angus-sired steers had greater marbling scores than Simmental and Limousin-sired steers and Angus and Charolais-sired steers had greater marbling scores than Limousin-sired steers (P < 0.05). Angus, Limousin, and Hereford-sired steers produced the most tender LM as evaluated by WBSF; Angus-sired carcasses (3.82kg) were more tender than Charolais (4.30kg) and Simmental-sired carcasses (4.51kg; P < 0.05). Limousin and Hereford-sired steers (3.70 and 3.83kg, respectively) also had more tender steaks than Simmental-sired steers.

Substituição de virginiamicina por produtos à base de levadura (Saccharomyces cerevisiae) em dietas de bovinos: Digestibilidade e parâmetros ruminais

Abstract The aim of this study was to evaluate the effect of substituting virginiamycin with yeastbased products in high-energy diets containing monensin on the nutrient digestibility and ruminal parameters of cattle. Five crossbred Nellore × Holstein steers (initial body weight 281 kg ± 9.2 kg) were allotted to a 5 × 5 Latin square design. The diets were composed in dry matter basis of corn silage (355 g kg-1), and concentrate composed of ground corn, soybean meal, soybean hulls,mineral mix, limestone, salt and urea (645 g kg-1). The treatments were: 1 - control, 18 mg kg-1 dry matter (DM) virginiamycin (VM); 2 - enriched yeast culture (Saccharomyces cerevisiae) at 7 g animal day-1 (EYC 7); 3 - enriched yeast culture (S. cerevisiae) at 14 g animal day-1 (EYC 14); 4 - autolyzed yeast (S. cerevisiae) at 7 g animal day-1 (AY 7); and 5 - autolyzed yeast (S. cerevisiae) at 14 g animal day-1 (AY 14). Monensin (18 mg kg-1 DM) was added to the mineral mix in all treatments. No significant differences (P &gt; 0.05) were found for DM intake (mean 8.36 kg DM), organic matter (OM) digestibility (average of 58.39%), or mean ruminal pH (mean 6.75) among treatments. Moreover, the treatment did not have a significant effect on the short-chain fatty acid or ammonia nitrogen concentrations. These results indicated the possibility of replacing virginiamycin with yeast-based products at the lowest level (7 g of enriched yeast culture or autolyzed yeast per animal day-1) in high-energy diets containing monensin.

Feeding limestone buffer to limit-fed dairy steers fed a high inclusion rate of distiller grains.

The study objective was to evaluate dietary limestone buffer inclusion rates for impacting nutrient digestibility and excretion when growing dairy cattle are fed high distiller grains with solubles (DDGS) limit-fed ration. The hypothesis was that feeding more limestone buffer would offset a low rumen pH when feeding a high DDGS inclusion rate. Five ruminally cannulated Holstein and Brown Swiss steers were used in a crossover design having 2-wk periods to evaluate high and low buffer inclusion rates when limit-fed. Treatments were similar in ingredient composition being: 1) 40% DDGS at 0.80% high CaCO3 buffer inclusion (HIGH) and 2) 40% DDGS with 0.25% low CaCO3 buffer inclusion (LOW) with the remaining ration consisting of grass hay with minerals and vitamins. Rations were limit-fed at 2.50% of body weight (BW) using Calan feeding doors with steers being weighed every 2wk with ration amounts adjusted accordingly. Rumen fluid was collected via the ruminal cannula at the start and end of each period for pH, ammonia-n, and volatile fatty acid (VFA)s. Fecal grab samples were collected at the end of each period for measurement of total-tract nutrient digestibility. There were no treatment-by-period interactions (P > 0.10) for any of the growth parameters measured. Gains in frame growth parameters were similar (P > 0.10) for steers fed both rations. BWs and gains were similar (P > 0.10) for steers fed both rations. Steers fed the LOW ration demonstrated a numeric improvement in average daily gain combined with a tendency (P < 0.06) for lower dry matter intake resulting in an improved (P < 0.01) feed efficiency (gain:feed) compared with steers fed the HIGH ration. Steers fed HIGH demonstrated greater (P < 0.01) ruminal ammonia-N and isovalerate concentrations compared with steers fed the LOW buffer ration. Steers fed both buffer inclusion rates were similar (P > 0.10) for ruminal pH and remaining VFAs concentrations. Steers fed both buffer inclusion rates were similar (P > 0.10) in DM and organic matter digestibilities. Limit-feeding a high DDGS inclusion rate ratio combined with a low buffer inclusion rate improved feed efficiency while maintaining growth performance. The study hypothesis was rejected in that feed efficiency can be enhanced when feeding a high DDGS ration by feeding a low calcium carbonate buffer.

Influence of metabolizable protein and methionine supplementation on growth-performance of Holstein steer calves during the initial 112-d feedlot growing phase.

The objective was to examine the effects of metabolizable protein (MP) and ruminal-protected methionine supplementation on growth performance of Holstein steer calves during the initial feedlot growing phase (112 d). One hundred eighty Holstein steer calves (122 ± 7kg) were blocked by weight and assigned to 30 pens (6 steers per pen). Five treatments were applied: 1) control, a diet based on steam-flaked corn containing urea and dry distillers grains plus solubles as supplemental N sources with no amino acid addition; 2) control diet plus blood meal supplementation; 3) diet from treatment 2, with 0.064% Smartamine M (70% methionine; Adisseo, Alpharetta, GA) supplementation; 4) diet from treatment 2 with 0.096% Smartamine M supplementation; 5) diet from treatment 2 with 0.128% Smartamine M supplementation. All diets were formulated to exceed the estimated MP requirements. The estimated metabolizable lysine, as well as methionine, was deficient in the control diet. Blood meal was added to the control diet to meet estimated lysine requirements (diet 2), the other diets had increasing concentrations of supplemental methionine. Supplemental MP enhanced (10%, P < 0.02) interim and overall 112-d average daily gain (ADG). Additional effects of supplemental methionine on ADG were not appreciable (P > 0.10). Supplemental MP did not affect (P > 0.10) dry matter intake (DMI) during the first 56-d period; however, it tended to increase (P = 0.08) DMI during the subsequent 56-d period. Overall, supplemental MP or methionine had no appreciable effect (P > 0.10) on DMI. Supplemental MP improved (P < 0.01) gain efficiency and estimated dietary net energy (NE) values during the initial 56-d period (11 and 7%, respectively) and overall (7 and 4%, respectively). Supplemental MP did not affect (P > 0.10) gain efficiency during the second 56-d period, although it tended to enhance (P = 0.08) estimated dietary NE. Supplemental methionine did not appreciably affect (P > 0.10) gain efficiency or estimated dietary NE. Therefore, adding MP to cover the estimated limiting amino acid supply in diets may enhance the gain efficiency and dietary energetics of growing Holstein calves. However, amino acid addition supplementation beyond the requirements may not produce extra productive performance of steer calves.

Influence of postruminal casein infusion and exogenous glucagon-like peptide 2 administration on the jejunal mucosal transcriptome in cattle.

We previously demonstrated that postruminal casein infusion and exogenous glucagon-like peptide 2 (GLP-2) administration independently stimulated growth and carbohydrase activity of the pancreas and jejunal mucosa in cattle. The objective of the current study was to profile the jejunal mucosal transcriptome of cattle using next-generation RNA sequencing in response to postruminal casein infusion and exogenous GLP-2. Twenty-four Holstein steers [250 ± 23.1 kg body weight (BW)] received a continuous abomasal infusion of 3.94 g raw corn starch/kg of BW combined with either 0 or 1.30 g casein/kg of BW for 7 d. Steers received subcutaneous injections at 0800 and 2000 h to provide either 0 or 100 μg GLP-2/kg of BW per day. At the end of the 7-d treatment period, steers were slaughtered for collection of the jejunal mucosa. Total RNA was extracted from jejunal mucosal tissue, strand-specific cDNA libraries were prepared, and RNA sequencing was conducted to generate 150-bp paired-end reads at a depth of 40 M reads per sample. Differentially expressed genes (DEG), KEGG pathway enrichment, and gene ontology enrichment were determined based on the FDR-corrected P-value (padj). Exogenous GLP-2 administration upregulated (padj < 0.05) 667 genes and downregulated 1,101 genes of the jejunal mucosa. Sphingolipid metabolism, bile secretion, adherens junction, and galactose metabolism were among the top KEGG pathways enriched with upregulated DEG (padj < 0.05) in response to exogenous GLP-2 administration. The top gene ontologies enriched with upregulated DEG (padj < 0.05) in response to exogenous GLP-2 administration included nutrient metabolic processes, brush border and bicellular tight junction assembly, and enzyme and transporter activities. Exogenous GLP-2 administration increased or tended to increase (padj < 0.10) brush border carbohydrase (MGAM, LCT, TREH), hexose transporter (SLC5A1, SLC2A2), and associated transcription factor (HNF1, GATA4, KAT2B) mRNA expression of the jejunal mucosa. Gene ontologies and KEGG pathways that were downregulated (padj < 0.05) in response to exogenous GLP-2 were related to genetic information processing. Postruminal casein infusion downregulated (padj < 0.05) 7 jejunal mucosal genes that collectively did not result in enriched KEGG pathways or gene ontologies. This study highlights some of the transcriptional mechanisms associated with increased growth, starch assimilation capacity, and barrier function of the jejunal mucosa in response to exogenous GLP-2 administration.

Effect of wheat middling incorporation into wet corn distillers grains with solubles on apparent diet digestibility and ruminal fermentation characteristics in growing and finishing diets.

Two separate cross-over experiments were conducted to evaluate the effects of incorporating wheat middlings into wet corn distillers grains with solubles (WDGS) on apparent diet digestibility and ruminal fermentation characteristics in growing and finishing diets. In experiment 1, four ruminally cannulated heifers (313 ± 42.9kg) were limit fed a high-energy growing diet that included WDGS (CON) or WDGS + wheat middlings (CON + WM) at 40% of diet dry matter (DM). The diet also contained (DM basis) 39.5% dry-rolled corn, 7.5% supplement, and 13% warm-season grass hay. In experiment 2, four ruminally cannulated Holstein steers (321 ± 17.4kg) were fed a finishing diet that included WDGS (CON) or WDGS + wheat middlings (CON + WM) at 30% of diet DM. The diet also contained (DM basis) 60.3% dry-rolled corn, 2.7% supplement, and 7.0% warm-season grass hay. Experiments consisted of two 15-d periods that were conducted concurrently. Each period included 10 d of diet adaptation, 4 d of fecal collection, and 1 d of ruminal fluid collection. Fecal samples were collected on days 11 to 14 of each period and composite samples were analyzed for chromium to estimate apparent diet digestibility. On day 15, ruminal fluid samples were collected prior to feeding and again at 2, 4, 6, 8, 12, 18, and 24-h post-feeding. In experiment 1, DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake did not differ (P ≥ 0.11) between diets; however, starch intake was greater (P = 0.03) for heifers fed CON + WM compared with CON. Apparent DM, OM, NDF, and starch digestibilities were similar between diets (P ≥ 0.13), but feeding CON + WM tended to lead to lesser (P = 0.06) apparent ADF digestibility. Ruminal pH and total volatile fatty acid concentrations did not differ between diets (P ≥ 0.16); however, ruminal ammonia concentrations tended to be less (P = 0.09) for CON + WM compared with CON. In experiment 2, DM intake did not differ (P = 0.65) between diets. Apparent DM digestibility was greater (P = 0.01) for CON + WM compared with CON but the difference was small. Intake and apparent digestibility of OM, NDF, ADF, and starch did not differ (P ≥ 0.25) between diets. Ruminal ammonia concentrations were lesser (P = 0.03) while ruminal pH was greater (P = 0.02) for CON + WM compared with CON. Overall, incorporation of wheat middlings into WDGS had minimal impacts on feed intake, apparent diet digestibility, and ruminal fermentation characteristics when fed to growing and finishing cattle.

Effect of bittern immersion on textural properties and water-holding capacity in beef.

Hard meat has low market value; hence, we used bittern as a novel meat tenderizer for bovine M. semitendinosus, one of a hard muscle. We investigated the effects of beef immersion in bittern, a basic solution primarily comprising MgCl2, on textural properties and water-holding capacity. Muscle samples from M. semitendinosus of Holstein steers were immersed in seven different solutions (RO, NaCl, MgCl2, red wine, pH 3, bittern, and pH 8) and heated at 80°C for 5min. The pH of the beef and immersion solutions, water-holding capacity, and maximum load of the meat were measured. Although beef immersed in red wine (pH 3) had a lower pH and water-holding capacity, that immersed in bittern (pH 8.4) had a higher pH and higher water holding capacity. These results indicate that immersion in acidic red wine may harden beef and that immersion in basic bittern may be more effective in maintaining water-holding capacity and softening beef.

104 Development of an Experimental Model to Induce Liver Abscesses in Steers Using an Acidotic Diet Challenge and Oral Bacterial Inoculation

Abstract The objective of this study was to develop a model for liver abscesses (LA) in Holstein steers by using an acidotic diet or acidotic diet plus intraruminal inoculation of Fusobacterium necrophorum, Salmonella enterica serotype Lubbock, and Truperella pyogenes. Holstein steers (n = 40; initial BW = 84.9 + 7.1 kg) were individually housed and randomly assigned to either a negative control diet (CON), an acidotic diet (AD), or an acidotic diet plus intraruminal inoculation with the bacterial mixture [ADB; (1 × 109 colony forming unit (CFU)/mL of each bacteria]. Steers in AD and ADB were cycled on (3 d) and off (2 d) a high-starch diet 20 days before intraruminal inoculation of ADB. Following inoculation, AD and ADB remained on the acidotic diet for the remainder of the study. Ruminal pH boluses were randomly inserted into 19 steers across treatments to monitor ruminal pH throughout the study. Steers were euthanized and necropsied to record gross pathology on the lung, rumen, liver, and colon. Culture techniques were used to determine the prevalence inoculated bacteria within LA. Quantitative polymerase chain reaction methods were used to quantify F. necrophorum in rumen tissue. Data were analyzed as a completely randomized design with animal as the experimental unit, where an α of ≤ 0.05 determined significance. Liver abscess prevalence was 43% in ADB vs. 0% in AD and CON treatments (P &amp;lt; 0.01). Ruminal damage was 51.1% greater in ADB than in AD and 78.6% greater than in CON (P ≤ 0.05). There were no pathological differences in the lungs and colons among treatment groups (P ≥ 0.14). There was a treatment × time interaction for ruminal pH, where pH decreased below 5.6 in AD and ADB calves during each cycle of the acidotic diet (P &amp;lt; 0.01). The ADB contained a greater concentration of F. necrophorum subsp. Necrophorum and subsp. Fundliforme within rumen tissue (P ≤ 0.03). Of the LA cultured, 100% contained F. necrophorum, 50% S. enterica, and 0% contained T. pyogenes. The F. necrophorum subsp. Necrophorum was phylogenetically typed and identical to the strain (FN-8LI) infused in the bacterial inoculation. These data suggest that acidotic diet in combination with intraruminal inoculation of the bacterial mixture is sufficient to induce liver abscesses and provides insight on possible mechanisms and origins of LA. Further studies are needed to validate these results and determine if this model may be used to study novel intervention methods.

PSI-6 Effects of a Postbiotic Program Consisting of Liquid and Solid Saccharomyces Cerevisiae Fermentation Products on Digestibility, Ruminal Fermentation, and Plasma Metabolome of Finishing Beef Steers

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

PSI-13 Effects of a Postbiotic Program Consisting of Liquid and Solid Saccharomyces Cerevisiae Fermentation Products on Ruminal Microbiome Composition and Microbial Functions of Finishing Beef Steers

Abstract We assessed the effects of a postbiotic program consisting of liquid and solid Saccharomyces cerevisiae fermentation products (SCFP) on the ruminal microbiome and fermentation characteristics of beef steers. Eight Holstein steers (BW 467 ± 13.9 kg) with rumen cannulas were used in a crossover design study with 21-d per period and 7-d washout in between periods. Steers were blocked based on initial BW and assigned to one of two treatments: 1) Control, basal diet, or 2) SCFP, basal diet plus one day feeding of LiquiCare RTU (Diamond V, Cedar Rapids, IA; dosed via rumen cannula at 11 mL/100 kg BW), followed by daily feeding of 12 g/d NaturSafe (Diamond V, top-dressed). Rumen fluid samples were collected on d 0, 1, 2, 3, 5 and 21 at 0, 4, 8, or 12 h post morning feeding via rumen cannula for pH, VFA and NH3-N analyses. Samples collected at 4 h post morning feeding on d 0, 2 and 21 were subjected to DNA extraction and shotgun Nanopore sequencing to determine microbiome composition and carbohydrate active enzymes (CAZy) functional potential. Statistical model included the fixed effects of treatment, period, day and their interactions and random effect of animal. Feeding SCFP tended to reduce ruminal lactate (0.09 vs. 0.02 mM, P = 0.10), and reduced ruminal NH3-N (4.86 vs. 6.83 mg/dL, P = 0.04) on d 21. Ruminal total VFA concentration was increased (P = 0.01) by feeding SCFP 4-h post-feeding on d 5 and numerically increased 4-h post-feeding on day 21 (133.3 vs. 151.2 mM, P = 0.12). Treatments did not affect species or CAZy alpha- and beta-diversity. Steers received liquid postbiotic on d 2 exhibited a positive correlation (P &amp;lt; 0.05) between propionate molar proportion and glycosyl transferases (GT), glycoside hydrolases (GH), carbohydrate esterases, and carbohydrate binding modules (CBM); and a negative correlation (P &amp;lt; 0.05) between acetate molar proportion and polysaccharide lyases, GT, GH, and CBM, which was not observed in Control. Additionally, SCFP steers had higher (P = 0.05) CBM functional potential on d 21 than on d 0, while CAZy class abundances did not change over time in Control steers. Differential network analysis indicated a greater normalized degree for GT in the SCFP steers compared with Control on d 21. There were 2, 6 and 12 differently abundant species (P &amp;lt; 0.01) between SCFP and Control on d 0, 2 and 21, respectively, suggesting supplementing SCFP altered the abundances of more species over time. Our results showed that the postbiotic program altered the metabolic pathways of ruminal microbes toward greater propionate production, and improved abundance of carbohydrate binding modules. Our results also showed that glycosyl transferases had a greater promotive role in the ruminal enzymatic network of SCFP steers.

PSVII-19 Evaluation of Live and Carcass Performance of Holstein Steers Fed Lubabegron During the Finishing Period

Abstract The objective of this study was to evaluate the effect of duration of lubabegron supplementation on live and carcass performance of Holstein steers. Holstein steers (n = 330) were enrolled in a feeding program supplementing lubabegron daily into a total mixed ration (TMR) at 3.2 g/ton for 0 (control) 28, 56, or 84 d. Steers were stratified by initial body weight (BW = 538 ± 37 kg) and then randomly assigned to treatments and pens. There were 8 pens total with approximately 40 head per pen. A GrowSafe feed intake recording system was used for the duration of the study to collect daily feed intake and feeding behavior on individual animals. Samples of premix were taken weekly for treatments to ensure nutrient requirements were being met and lubabegron concentration was accurate. Prior to departure from the feedlot and immediately upon arrival at the harvest facility, mobility of all animals was assessed. Individual IDs were matched with carcass identification and used throughout the harvest process to ensure the integrity of individual data. Carcasses were chilled for 48 hours and then went through USDA quality and yield grading protocols. Cattle fed lubabegron for 28 and 56 d had the greatest (P ≤ 0.01) average daily gain, total gain, as well as the least feed to gain ratio (P = 0.01) as compared with control steers and those fed lubabegron for 84 d. Conversely, control steers had the greatest (P &amp;lt; 0.05) feed-to-gain ratio. No differences (P ≥ 0.08) were observed between supplementation time for initial body weight, final body weight, and dry matter intake. Additionally, mobility scores were not different among supplementation protocols, neither at the feed yard, nor the harvest facility (P ≥ 0.64). Steers within the 28 d and 56 d treatments had among the greatest (P = 0.02) hot carcass weight. Ribeye area was increased (P = 0.01) by at least 3.87 cm2, when the cattle were fed lubabegron for any period of time. Cattle fed lubabegron for 56 and 84 d had an increased (P = 0.01) dressing percentage compared with 28 d and controls. While overall marbling scores were decreased (P = 0.04), the percentage of carcasses receiving USDA Prime, Choice, or Select quality grades were not different for animals receiving supplementation (P ≥ 0.31). The data suggest that lubabegron can positively influence live growth attributes; thus, translating to increased carcass yield, without sacrificing animal mobility or carcass quality.

103 Development of a Novel, Experimental, Minimally Invasive Model to Investigate the Genesis and Etiology of Liver Abscesses in Cattle

Abstract Most research surrounding liver abscesses involves post-hoc evaluation of naturally occurring abscesses in production settings. Few studies have been designed to experimentally induce abscesses with the purpose of identifying a time course, causality, and associated physiological implications. Therefore, we set out to develop a minimally invasive, reliable, and repeatable model to induce liver abscesses in calves in a controlled research environment to elucidate the genesis and etiology of the disease, with the ultimate goal of developing abscess reduction strategies. Experiment 1 was an attempt to induce abscesses by intraruminal inoculation with Fusobacterium necrophorum, Salmonella lubbock, and Truperella pyogenes (FST) following an intravenous lipopolysaccharide challenge. Holstein steers were harvested 3- and 10-d after inoculation, but no abscesses were detected. Experiments 2 and 3 involved diet manipulation by cycling calves on and off a high-starch, acidotic diet followed by intraruminal inoculation of microbes. In Experiment 2, Holstein calves were fed a negative control diet, an acidotic diet, and an acidotic diet plus bacterial inoculation with FST. No abscesses formed in the control or acidotic diet calves, but 43% of calves fed the acidotic diet with FST inoculation formed liver abscesses, suggesting that acidosis alone is insufficient to produce abscesses. In Experiment 3, treatments consisted of Holstein steers fed a negative control, an acidotic diet, an acidotic diet plus ruminal Fusobacterium necrophorum (F), and an acidotic diet plus Fusobacterium and Salmonella (FS). Again, there were no abscesses in the control or calves fed an acidotic diet alone; however, 40% of calves receiving F presented with an abscess, and 50% of the calves that received FS presented with abscesses. These data suggest that ruminal acidosis in conjunction with a ruminal load of pathogens commonly associated with liver abscesses provides a model that will induce liver abscesses. While the role of barrier dysfunction in the rumen and the lower gastrointestinal tract in formation of abscesses is not fully understood, this work provides a foundation to further explore the etiology of this disease and potential mitigation strategies.

285 Duration of Ergovaline Exposure Influences Serotonin-Mediated Vasoconstriction and Vasorelaxation of Bovine Vasculature

Abstract Ergovaline (ERV), produced in toxic endophyte-infected tall fescue, causes potent vasoconstriction of bovine peripheral and visceral vasculature. Ergovaline acts as both an agonist and an antagonist in bovine gut blood vessels through serotonin (5-HT) receptors and it appears that the type of action could be influenced by the extent of ERV exposure. Because it was unclear how the duration of ERV exposure influences 5-HT-mediated vasoactivity, experiments were designed to evaluate how simultaneous or prior ERV exposure influenced 5-HT-mediated vasoactivity of mesenteric artery (MA) and vein (MV) segments from Holstein steers (n = 10). Isolated vessel segments were incubated in Krebs-Henseleit buffer containing 0, 0.01, or 0.1 mM ERV for 24-h befoe the 5-HT dose-response or exposed to fixed concentrations of 0, 0.01, or 0.1 mM ERV simultaneously during the 5-HT dose-response. Vessels were suspended in chambers of a multi-myograph containing 5 mL of continuously oxygenated Krebs-Henseleit buffer and equilibrated to 1 g tension for 90 min. Vessels were exposed to increasing concentrations of 5-HT (5 × 10-8 M to 1 × 10-4 M) every 15 min and contractile responses were normalized as a percentage of the maximum contractile response induced by 120 mM KCl reference addition. Two-way analysis of variance was used to separately analyze data for each vessel type and duration of exposure using the MIXED procedure of SAS for the main effects of 5-HT and ERV concentration and the 5-HT × ERV concentration interaction. When 5-HT concentration increased from 5 ′ 10-8 M to 1 ′ 10-6 M, simultaneous addition of 0.1 mM ERV increased (P &amp;lt; 0.01) the contractile response of MV compared with additions of 0 mM ERV and 0.01 mM ERV. At 1 ′ 10-4 M 5-HT, the simultaneous presence of 0.01 mM ERV and 0.1 mM ERV decreased (P &amp;lt; 0.01) the contractile response of both MA and MV compared with 0 mM ERV addition. As 5-HT concentrations increased, the contractile response increased (P &amp;lt; 0.01) in both MA and MV with no previous ERV exposure, but decreased in MA and MV with 24-h prior exposure to 0.01 mM ERV and 0.1 mM ERV. These data demonstrate that the duration of ERV exposure influences 5-HT-mediated vasoconstriction and likely vasorelaxation in bovine mesenteric vasculature. If ERV and 5-HT exposure occur simultaneously, ERV can act as a partial agonist of 5-HT-mediated vasoconstriction. If 5-HT exposure occurs after blood vessels have had prior ERV exposure, it appears that 5-HT may induce vasorelaxation of blood vessels. More research is needed to identify receptors and mechanisms involved with 5-HT-mediated vasoconstriction and vasorelaxation before and after exposure to ERV. This will aid in the development of strategies for alleviating symptoms of sustained vasoconstriction that occur during fescue toxicosis in ruminants.

PSII-11 Effects of Cannabidiol on Viability and Inflammatory Response in Bovine Primary Ruminal Epithelial Cells

Abstract Phytochemicals derived from hemp (Cannabis sativa) have been noted for their possible beneficial effects, including immunomodulation. Cannabidiol (CBD) may be a promising target as a therapy for gastrointestinal inflammation; however, the effects have not been explored in ruminants. The objective of this study was to investigate immunomodulatory properties of CBD in primary ruminal epithelial cells (REC). REC were isolated from ruminal papillae of yearling Holstein steers (n = 7). A preliminary experiment was performed to determine cytotoxicity of CBD using alamarBlue. Cells were exposed to either 10 or 50 µM CBD for 6 or 24 h. CBD at 10 µM did not affect viability. Growth was inhibited by over 60% at 50 µM for 24 h (P &amp;lt; 0.05), and therefore, 10 µM was selected for use. Two experiments, each 24h in duration, were conducted to explore various responses to CBD when inflammation was induced in REC with lipopolysaccharide (LPS). In Experiment 1, LPS was added prior to CBD exposure, simulating a therapy for established inflammation. In Experiment 2, LPS was added after CBD exposure, simulating a preventative strategy. Treatment groups for both experiments are described in Table 1. Total RNA was extracted from REC and relative gene expression of cytokines TNF, IL1B, IL6, CXCL8 and CXCL10 was evaluated using real time qPCR. Expression was normalized to the geometric mean of two stable housekeeping genes, GAPDH and STX5. All statistical analyses were performed using the lme4 and emmeans packages of R with exposure treatment as the fixed effect. In Experiment 1, expression of TNF, IL1B and CXCL8 was greater for LPS8 compared with CON by 5-, 29- and 14-fold, respectively, but less than LPS24 (P &amp;lt; 0.05). The LPS24+CBD16 group resulted in an upregulation of IL1B compared with CON, but not to the same magnitude as LPS24 (27- vs 93-fold; P = 0.002). A 3-fold down-regulation of IL6 was observed with the addition of CBD alone compared with CON (P &amp;lt; 0.001). Experiment 1 results suggest that CBD may reduce cytokine transcription during LPS-induced inflammation. For Experiment 2, compared with LPS8, there was less expression of IL6 and CXCL10 in CBD24+LPS8 (P &amp;lt; 0.05). There was a 9-fold upregulation of IL6 for CBD16-LPS8 (P &amp;lt; 0.001), but no difference between CON and CBD16-LPS8 for CXCL10 expression. Compared with CON, CBD24 resulted in a 2- and 6-fold down-regulation of IL6 (P = 0.003) and CXCL10 (P = 0.002). Experiment 2 results suggest that IL6 expression was influenced by CBD, but only while present in the media, while CXCL10 expression was suppressed by CBD, even after its removal. Overall, this study provides evidence of immunomodulation by CBD during a pro-inflammatory response in primary REC in culture.

327 A Novel, in Vivo Model to Increase Endogenous Pancreatic and Small Intestinal Carbohydrase Activity to Evaluate Limitations of Small Intestinal Starch Digestion in Cattle

Abstract Consumption of high-grain diets by cattle can result in large quantities of starch that flow to the small intestine for potential enzymatic digestion. However, small intestinal starch digestion is potentially limited because of insufficient activity of pancreatic and/or small intestinal carbohydrases. Studies suggest regulation of carbohydrase activity is complex in cattle and perhaps uncoordinated in response to luminal carbohydrate flow. The objective of this experiment was to use postruminal casein infusion and exogenous glucagon-like peptide 2 (GLP-2) administration, known stimulators of pancreatic and small intestinal function, to evaluate their effects on pancreatic and small intestinal carbohydrase activities. Twenty-four Holstein steers [250 ± 23 kg body weight (BW)] were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. Steers were fed an alfalfa cube-based diet to limit dietary starch intake. Steers received a continuous abomasal infusion of 4 g/kg of BW of raw corn starch combined with either 0 or 1.33 g/kg of BW of casein for 7 d. Steers received subcutaneous injections in two portions daily of excipient (0.5% bovine serum albumin) or 100 µg/kg of BW GLP-2. This resulted in four treatments: control, casein, GLP-2, and casein + GLP-2. At the end of the 7-d treatment period, steers were slaughtered for pancreatic and small intestinal tissue collection. Data were analyzed using the GLM procedure of SAS. Postruminal casein infusion increased (P ≤ 0.03) pancreatic mass by 12.6%, total pancreatic α-amylase activity by 50%, and postruminal starch disappearance from 96.7% to 99.3%. Exogenous GLP-2 increased (P &amp;lt; 0.01) total small intestinal mass and small intestinal mucosal mass by 1.2 kg and 896 g, respectively. Relative to control, GLP-2 and casein + GLP-2 treatments increased (P = 0.04) total small intestinal α-glucosidase activity (sum of maltase, isomaltase, glucoamylase) by 83.5%. Total small intestinal maltase, isomaltase, and glucoamylase activity was 90%, 100%, and 66.7% greater for GLP-2 and casein + GLP-2 steers compared with control. The use of postruminal casein infusion and exogenous GLP-2 administration resulted in four distinct carbohydrase activity phenotypes. Relative to control, casein increased pancreatic α-amylase activity, GLP-2 increased small intestinal α-glucosidase activity, and the combination of casein and GLP-2 increased both pancreatic α-amylase activity and small intestinal α-glucosidase activity. This approach provides a novel in vivo animal model to selectively increase endogenous carbohydrase activity to overcome complications of coordinating carbohydrase activity with luminal nutrient flows. This model could be useful to understand physiological mechanisms that might improve small intestinal starch assimilation and efficiency of cattle consuming high-grain diets.

PSXI-6 The Effects Cattle Breed (Holstein Vs Angus × Holstein) on Growth Performance, Energetic Efficiency, and Carcass Characteristics of Calf-Fed Steers

Abstract Objective of the current study was to evaluate the effects of cattle breed (Holstein vs Angus × Holstein) on growth performance, energetic efficiency, and carcass characteristics of calf-fed steers. Eighty Holstein (HOL), initial body weight (IBW) of 128.7 ± 3 kg, and 80 Angus × Holstein cross (CROS) with IBW of 127.1 ± 3 kg, were blocked by IBW and randomly assigned to 40 pens (4 steers/pen; 20 pens per breed). All steers were fed a similar steam-flaked corn-based diet (63.5% steam-flaked corn, 12.0% hay, 17.5% of dry distillers grains with solubles, 4.0% cane molasses, and 3.0% vitamin/mineral supplement). All cattle were slaughtered after 328 days of feeding. There was no effect (P ≥ 0.13) of cattle breed on final body weight (615 ± 22 kg) and overall average daily gain (1.48 ± 0.07 kg/day). However, calf-fed HOL steers had greater (P = 0.04) overall dry matter intake compared with calf-fed CROS steers (8.06 vs. 7.79 ± 0.39 kg/day; respectively). Therefore, calf fed CROS steers had greater (P ≤ 0.01) grain to feed ratio compared with calf-fed HOL steers (0.192 vs. 0.182 ± 0.005; respectively). Moreover, calf-fed CROS steers had greater (P &amp;lt; 0.01) utilization of dietary net energy for maintenance (2.29 vs. 2.29 ± 0.06 Mcal/kg; respectively) and gain (1.51 vs 1.61 ± 0.06 Mcal/kg; respectively) compared with calf-fed HOL steers. Calf-fed CROS steers had greater (P ≤ 0.02) hot carcass weight (HCW; 386.3 vs. 375.2 ± 14.7 kg; respectively), dressing percentage (DP; 62.3 vs. 61.4 ± 1.05%; respectively), longissimus muscle area (LMA; 86.9 vs. 79.1 ± 4.83 cm2; respectively), backfat thickness (0.89 vs. 0.55 ± 0.12; respectively), and marbling score (538 vs. 449 ± 48; respectively). However, there was no effect (P = 0.26) of cattle breed on calculated USDA yield grade (2.94 ± 0.24). Moreover, there was no effect (P = 0.39) of cattle breed on incidence of liver abscesses. Therefore, cross breeding calf-fed Angus × Holstein increased HCW, DP, LMA, and marbling compared with purebred calf-fed Holstein steers. Moreover, regardless of cattle breed, calf-fed steers in the current study had only 3.75% of liver with abscess.

Effects of energy levels on growth performance, carcass characteristics, and fatty acid composition of Holstein steers at different slaughter ages.

We investigated the effect of energy levels on growth performance, carcass characteristics, and fatty acid composition of Holstein steers at different slaughter ages. Forty Holstein steers with an average body weight (BW) of 234.21 ± 7.42 kg and 7.78 ± 0.22 months were randomly allocated to two experimental groups; a 22-month-old experimental group and a 24-month-old experimental group. Total digestible nutrients (TDN) for each group were set to 70% (T1) and 72% (T2) during fattening phase and 74% (T3) and 76% (T4) for the finishing phase, respectively. No difference was observed in the final BW between the experimental groups during the fattening phase. However, in the finishing phase, the final BW of T4 (820.31 kg) group was significantly higher than that of T1 (745.57 kg; p < 0.05). The average daily gain (ADG) of T2 group in the finishing phase and overall period were 1.27 kg and 1.26 kg, respectively, which were significantly higher than those of T1 (1.11 kg and 1.12 kg; p < 0.05). The feed conversion ratio (FCR) and TDN conversion ratio of T2 group in the finishing phase also decreased by 10.23% and 7.73%, respectively, compared to those of T1. The cold carcass weight of T4 group was significantly higher (p < 0.05) than that of T1, whereas back fat thickness, longissimus area, and marbling score were not significantly different among groups. No differences were observed in physicochemical characteristics of the carcass including moisture, crude protein, and crude fat content among groups. However, the composition of fatty acids differed significantly between the groups. The content of C18:0 was significantly lower (p < 0.05) in T4 than in T1 group, and the content of C18:2 was higher in T4 than in T1 and T3 (p < 0.05). Therefore, feeding Holstein steers at a high-energy feeding level during the fattening and finishing phases improves ADG and reduces the slaughter age from 24 months to 22 months.

194 A Systems Approach to Deriving Carcass Value from Holstein x Simangus Cattle in an Accelerated Finishing Model

Abstract Crossbreeding dairy cows with beef sires has increased in the U.S. dairy industry. This beef x dairy mating results in dairy-beef which has altered the U.S. fed beef supply. The predominant mating has been Holstein x Angus, thus research was conducted to determine the effects of Holstein x SimAngus breeding on growth performance, carcass characteristics, and fresh meat quality. Starting on d 1, Holstein steers (n = 9) and Holstein x SimAngus (HolSim) steers (n = 12) were fed once daily at 0830 h, until an end weight of 635 kg was reached. Holstein steers averaged 421 d and HolSim steers averaged 432 days on feed. Daily feed offered was delivered into a semi-autonomous feed monitoring system designed to measure individual animal intake and feeding behavior (GrowSafe System Ltd). Steer body weight was recorded every 28 d. Data collected were used to calculate dry matter intake (DMI), average daily gain (ADG), and gain to feed ratio (G:F). Steers were humanely slaughtered under USDA inspection, immediately following slaughter hot carcass weight (HCW) was recorded and 48 h following slaughter, carcass length, body width, backfat thickness and area of the longissimus muscle (LM) was recorded. Strip loins were collected from each carcass and aged for 14 d. After aging, Warner-Bratzler shear force (WBSF) and slice shear force (SSF) were determined. Remaining steaks were placed under retail display for 7 d. Objective color was measured after 0, 1, 3, 5, and 7 d in retail display. No differences were observed for ADG and G:F between Holstein and HolSim steers (P &amp;gt; 0.05). A tendency was observed for Holstein steers to have a greater DMI compared with HolSim steers (P = 0.0646). The HolSim steers had greater HCW and dressing percentages compared with Holstein steers (P &amp;lt; 0.0001). The HolSim carcasses had shorter carcass lengths and body widths compared with Holstein carcasses (P = 0.0005). Holstein carcasses had less backfat compared with HolSim carcasses (P = 0.0034). The LM area was larger in HolSim carcasses (P &amp;lt; 0.0001). No differences were observed for WBSF or SSF (P &amp;gt; 0.05). Strip steaks from HolSim steers had less deoxymyoglobin and greater oxymyoglobin values on d 0 of retail (P &amp;lt; 0.05). Strip steaks from HolSim steers had greater a* and saturation index values on d 7 in retail (P &amp;lt; 0.05). Strip steaks from HolSim steers had decreased metmyoglobin values and greater oxymyoglobin values on d 7 in retail (P &amp;lt; 0.05). Thus, indicating strip steaks from HolSim steers had increased red color. Growth performance data in this study confirm previous literature reported when comparing dairy x dairy to beef x dairy steers. Carcass and fresh meat data suggest that Holstein x SimAngus steers had improved yield production compared with Holstein steers without a loss in quality when steers were fed to a weight constant end point.