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The objective of this experiment was to evaluate the effects of a phytogenic feed additive (PHYT) on the health and performance of newly-received, high-risk calves. Auction market derived crossbred beef steers and bulls (n = 712; initial body weight; BW = 239 ± 6.8 kg) were stratified by sex, blocked by BW, and randomly allocated to experimental treatments (n = 9 pens per treatment; n = 24 to 29 calves per pen). Experimental treatments included: a control diet (CON), 250 mg · steer-1 · d-1 of PHYT (PHYT250), or 500 mg · steer-1 · d-1 of PHYT (PHYT500). Pen served as the experimental unit for all dependent variables. Contrasts were performed for PHYT inclusion (PHYT250 and PHYT500 vs. CON). No differences in BW existed between treatments throughout the experiment (P ≥ 0.20; PHYT vs. CON P ≥ 0.11). In the overall model, no differences (P ≥ 0.23) in average daily gain (ADG) existed between CON, PHYT250, or PHYT500. However, when comparing PHTY to the CON, ADG tended to be less in the calves receiving CON from d 0 through d 14 (P = 0.09). No differences in dry matter intake (DMI) existed between treatments throughout the experiment (P ≥ 0.27; PHYT vs. CON P ≥ 0.13). While there was no difference in gain to feed (G:F) in the overall model (P ≥ 0.26), the tendency observed for a difference in ADG from d 0 through d 14 did result in a similar tendency for G:F across the same interval when comparing PHYT to the CON (PHYT vs. CON P ≥ 0.10). A difference was observed in the percentage of steers treated once for bovine respiratory disease (BRD; P = 0.02), with CON being treated more frequently than PHYT500, while PHYT250 was intermediate and similar to both CON and PHYT500. When comparing PHYT to the CON, there was a decrease in the percentage of steers receiving PHYT to be treated once for BRD (P = 0.01). However, there were no differences in either the percentage of steers treated twice for BRD or the in the percentage of total BRD treatments administered (P ≥ 0.29; PHYT vs. CON P ≥ 0.14). The mortality percentage and the percentage of steers removed from the study were not different (P ≥ 0.16; PHYT vs. CON P ≥ 0.14); however, there tended to be more combined mortalities and removals for steers receiving PHYT than the CON (P = 0.08; PHYT vs. CON P = 0.09), with PHYT500 and CON tending to be different, and PHYT250 being intermediate and similar to both PHYT500 and CON. In summary, PHYT did not impact overall performance, but did reduce initial antimicrobial treatments for BRD. [ABSTRACT FROM AUTHOR]

The objectives of this experiment were to evaluate the effects of feeding Bacillus subtilis PB6 on clinical health, performance, and carcass characteristics of feedlot steers. Bos indicus crossbred steer calves (n = 397; 342 kg initial body weight [BW]) were randomly assigned to pens by initial BW; pens (n = 24) were randomly assigned to one of two of the following experimental treatments: 1) no supplemental dietary direct-fed microbial, control (CON; n = 12 pens) or 2) 13 g/steer daily B. subtilis PB6 (CLO; CLOSTAT, Kemin Industries, Des Moines, IA; n = 12 pens). Steers were housed in 12.2 × 30.5 m soil-surfaced pens; pen served as the experimental unit. The percentage of cattle treated once or twice for bovine respiratory disease (BRD) did not differ among treatments (P ≥ 0.27); BRD mortality also did not differ between CON and CLO (P = 0.34). During the receiving period, final BW (P = 0.97), average daily gain (ADG; P = 0.91), dry matter intake (DMI; P = 0.77), and gain:feed (P = 0.79) were not different among treatments. There was a tendency (P = 0.09) for CLO-supplemented steers to be 14% more efficient from days 0 to 14 of the receiving period. Final BW, overall finishing phase ADG, and DMI did not differ by treatment (P ≥ 0.14); ADG was 0.14 kg greater for CLO than CON (P = 0.03) from days 29 to 56 of the finishing period. Gain: feed tended (P = 0.07) to be 7% greater (0.144 vs. 0.141) for CLO than CON throughout the duration of the finishing period, and 6.7% greater (P = 0.08; 0.152 for CLO vs. 0.150 for CON) for the entirety of the experiment. Carcass traits did not differ among treatments (P ≥ 0.31). The results of this experiment suggest that supplementing 13 g/steer daily B. subtilis PB6 may improve feed efficiency in feedlot cattle. [ABSTRACT FROM AUTHOR]

Current dogma suggests increased dietary roughage may improve calf health at the expense of performance during receiving. In experiment 1, the effects of increasing dietary roughage on performance and clinical health of high-risk heifers was evaluated over a 56-d receiving period. Heifers (n  = 589; initial body weight; BW  = 230 ± 33 kg) were sourced from Oklahoma livestock auctions from April through October of 2019. Heifers were randomly assigned to pens, which were randomly assigned to 1 of 3 experimental dietary treatments in a randomized complete block design. Diets contained either: 1) 15% roughage (R15), 2) 30% roughage (R30), or 3) 45% roughage (R45) in the form of prairie hay. Orthogonal contrasts were used to test for linear and quadratic responses among experimental treatments. There was a linear decrease in overall average daily gain (ADG ; P  ≤ 0.0001) with increasing roughage inclusion which resulted in a linear decrease (P  ≤ 0.0001) in heifer final BW. A linear increase (P  ≤ 0.01) was observed for overall dry matter intake (DMI), and overall gain:feed (G:F) decreased linearly (P  ≤ 0.0001) as dietary roughage concentration increased. A quadratic response to decreasing roughage was observed (P  = 0.02) for the percent of calves treated three times for bovine respiratory disease (BRD). No other responses (P  ≥ 0.11) were detected in animal health variables. In experiment 2, Angus steers (n  = 12) and heifers (n  = 6; BW = 272 ± 28 kg) were acquired from a single ranch in Oklahoma to evaluate the same experimental dietary treatments on serum metabolite concentrations. Animals were randomly assigned to experimental treatments, with animal serving as the experimental unit in experiment 2. Statistical models for serum metabolites in experiment 2 were analyzed using repeated measures with the effects of treatment, time, and treatment × time. In experiment 2, there were tendencies for treatment × time interactions for blood urea nitrogen (BUN ; P  = 0.07) and nonesterified fatty acid (NEFA ; P  = 0.06) concentrations. No metabolites were affected by treatment (P  ≥ 0.11), while all metabolites were impacted by time (P  ≤ 0.02). In summary, growth performance was improved in calves as dietary roughage concentration decreased with minimal impacts on health and serum metabolites. These results suggest that diets containing as little as 15% roughage can be used during receiving to improve calf performance without compromising calf health when fibrous byproducts are included in the diet. [ABSTRACT FROM AUTHOR]

Two 89-d experiments (Exp 1 and Exp 2) evaluated the effects of feeding an immunomodulatory feed additive (NutraGen; NG) in calves following exposure to bovine viral diarrhea virus (BVDV) on d -3 and Mannheimia haemolytica (MH) infection on d 0. For each experiment, steers [body weight (BW) = 251 ± 38.2 kg)] were randomly allocated to 1 of 3 treatments. Treatments included a placebo (CON; Exp 1 n = 5; Exp 2 n = 5), a placebo fed from d -18 to d -3 followed by NG fed from d -3 to d 28 (CHLG; Exp 1 n = 5; Exp 2 n = 6), and NG fed from d -18 to d 28 (PREC; Exp 1 n = 6; Exp 2 n = 5). Data were analyzed using the GLIMMIX procedure of SAS Version 9.4 (SAS Institute, Cary, N.C.). Animal served as the experimental unit and time served as a repeated measure. Treatment, time, and the treatment × time interaction served as fixed effects. Block was included as a random effect. Multiple treatment × time interactions and time effects occurred for serum glucose, lactate, blood urea nitrogen, and non-esterified fatty acid concentrations (P ≤ 0.003) in both experiments. There was a general trend for serum glucose to decrease over time postchallenge, suggesting increased cellular utilization of glucose in response to the challenge. In Exp 1, treatment effects occurred for serum glucose (P ≤ 0.001) and serum lactate (P ≤ 0.01), where calves assigned to the CHLG treatment displayed the greatest concentrations of the metabolites. Blood urea nitrogen concentrations peaked at h 48 in Exp 1 and h 6 in Exp 2. There were no treatment effects or treatment × time interactions for serum cortisol, hair cortisol, or fecal corticosterone concentrations in either experiment (P ≥ 0.17). There were, however, multiple time effects for serum cortisol, hair cortisol, and fecal corticosterone concentrations in both experiments (P ≤ 0.02), indicating that the challenge directly impacted cortisol and corticosterone production. Serum cortisol steadily increased from h 96 to h 168 in both experiments. Trends in cortisol and corticosterone production were similar in both experiments; however, peak concentration times for these variables occurred later in Exp 2. These data suggest that feeding NG to calves may alter glucose availability and nutrient utilization in response to infection resulting from a bovine respiratory disease challenge. [ABSTRACT FROM AUTHOR]

Two 89-d experiments (Exp 1 and Exp 2) evaluated the effects of feeding an immunomodulatory feed additive (NutraGen; NG) in calves following exposure to bovine viral diarrhea virus (BVDV) on d -3 and Mannheimia haemolytica (MH) infection on d 0. For each experiment, steers [body weight (BW = 251 ± 38.2 kg were randomly allocated to 1 of 3 treatments. Treatments included a placebo (CON; Exp 1 n = 5; Exp 2 n = 5), a placebo fed from d -18 to d -3 followed by NG fed from d -3 to d 28 (CHLG; Exp 1 n = 5; Exp 2 n = 6), and NG fed from d -18 to d 28 (PREC; Exp 1 n = 6; Exp 2 n = 5). Data were analyzed using the GLIMMIX procedure of SAS Version 9.4 (SAS Institute, Cary, N.C.). Animal served as the experimental unit and time served as a repeated measure. Treatment, time, and the treatment × time interaction served as fixed effects. Block was included as a random effect. Cytokine data were tested for normality using the Shapiro-Wilk test, determined to be non-normal, and logarithm (base 10) transformed as a result prior to statistical analysis. Multiple time effects and treatment × time interactions occurred for serum MH, BVDV 1, and BVDV 2 antibody concentrations in both experiments (P ≤ 0.05). In Exp 1, there was a tendency for an overall treatment effect for calves assigned to the CON treatment to exhibit the greatest MH serum antibody concentrations (P = 0.06). While no differences were detected between treatment groups, BVDV 1 and BVDV 2 antibody concentrations peaked on the same day in both experiments, d 28 post-challenge. There were no treatment × time interactions, treatment effects, or time effects for serum TNF-α, IFN-γ, or IL-17A concentrations (P ≥ 0.13) in either experiment. In Exp 1, there was a treatment effect for serum IL-10 (P ≤ 0.0001), where calves assigned to the PREC treatment had increased serum IL-10 concentrations when compared with calves in the other treatment groups. In Exp 2, there was a tendency for a treatment effect for IL-10 concentrations, where calves assigned to the PREC treatment displayed decreased IL-10 concentrations when compared with calves in the other treatment groups (P = 0.07). These data suggest that feeding NG to calves prior to a stress experience may alter cellular responses. Overall, these experiments suggest that NG impacted antibody concentrations and cytokine expression during a bovine respiratory disease challenge. [ABSTRACT FROM AUTHOR]

Finishing cattle are fed diets high in concentrates to promote efficient deposition of both muscle and adipose tissue while decreasing cost of gain during finishing. The continued incidence of liver abscesses and increases in morbidity and mortality in the late finishing period have led to interest in increasing dietary roughage inclusion during late finishing. The objective of the current experiment was to evaluate the effects of increased roughage inclusion late in the finishing period on growth performance, carcass traits, blood metabolites, inflammation markers, and ruminal and faecal characteristics of feedlot steers. Crossbred beef steers (n = 60; initial body weight; BW = 289 ± 35,6 kg) were blocked by BW and assigned to experimental dietary treatments in a randomized complete block design during the final 58 d on feed. Experimental treatments included control (CON; 6% roughage dry matter; DM), intermediate (INT; 12% roughage DM), and high (HGH; 18% roughage DM) roughage diets (CON = 5 pens and INT and HGH = 4 pens; 4 steers per pen). All experimental diets contained dry-rolled corn, prairie hay, Sweet Bran (Cargill, Inc., Blair, NE), dry supplement, urea, and a corn-steep- and molasses-based liquid supplement. The inclusion rates of roughage and dry-rolled corn were adjusted for each experimental treatment, in which the increased roughage replaced dry-rolled corn. Overall dry matter intake (DMI) tended to increase linearly (P = 0,02) with increasing roughage inclusion. No differences in BW, overall average daily gain (ADG), or gain to feed ratio (G:F) were observed (P ≥ 0,72). Rib eye area increased linearly with increasing roughage inclusion (P = 0,02). Fat thickness, hot carcass weight (HCW), marbling, liver score, and kidney, pelvic, and heart fat (KPH) did not differ (P ≥ 0,29) among treatments. Steers consuming the HGH diet had a lower faecal pH at the end of the finishing period (P = 0,05) compared to CON and INT steers. Ruminal lactate was increased on d 14 for CON steers compared to other treatments (P < 0,001). No differences were observed for ruminal pH (P ≥ 0,11) among treatments at any collection. Results from the experiment suggest that increasing roughage late in the finishing period may not negatively impact growth performance or carcass characteristics but does alter feed intake and may alter fermentation and digestion. [ABSTRACT FROM AUTHOR]

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

The objective of this experiment was to determine the effects of increasing trace mineral (TM) supplementation on finishing cattle performance, carcass characteristics, TM balance, and antibody concentrations. Commercial Angus steers (n = 240; body weight, BW = 291 kg ± 27.4) were stratified by arrival BW and source and randomly assigned to 1 of 4 experimental treatments in a randomized complete block design (12 pens/treatment; 5 steers/pen). All steers underwent a TM depletion period for a minimum of 42-d prior to the administration experimental treatments. Treatments included a negative control (CON) in which cattle received no additional TM supplementation or TM supplementation treatments in which cattle received added Co, Cu, I, Mn, Se, or Zn from inorganic TM sources at 2016 Nutrient Requirements of Beef Cattle (NASEM) requirement levels (1X), at 2 times NASEM requirements (2X), or at 4 times NASEM requirements (4X). Selenium was included at 0.1, 0.2, and 0.3 mg/kg for 1X, 2X, and 4X respectively, based on federal law. There was no difference in overall BW, average daily gain (ADG), dry matter intake (DMI), or gain to feed (G:F) due to TM supplementation (CON vs. SUPP P ≥ 0.47). There was no difference in hot carcass weight, rib eye area, fat thickness, dressing percentage, marbling score, or USDA Yield Grade due to TM supplementation (CON vs. SUPP P ≥ 0.30). One steer was chosen at random from each pen to be evaluated for serum and liver TM status and antibody concentrations to common respiratory viruses. There was a treatment × day interaction for serum Co and liver Cu and Se (P < 0.0001). Serum Co was greatest for the 4X treatment from d 28 through harvest. Liver Cu was greatest for the 2X and 4X treatments from d 56 through harvest. Liver Se was greatest for 2X and 4X from d 28 through harvest. Serum Zn was greatest for the 4X treatment (P = 0.02). There was an effect of day on liver Co, Fe, Mn, Mo, and Zn (P ≤ 0.0001) and serum Cu, Mn, Mo, Se, and Zn (P ≤ 0.002). Concentrations for individual TM had different trends over time, however, all reported values were within normal ranges. There was an effect of time on bovine viral diarrhea virus Type 1A, bovine herpesvirus type 1, and bovine parainfluenza 3 virus antibody concentrations (P ≤ 0.0001). Supplementation of TM above NASEM requirements did not affect overall cattle performance, carcass characteristics, or antibody concentrations, but did affect the storage and circulation of certain TM. [ABSTRACT FROM AUTHOR]

Growth-promoting technologies such as implants, ionophores, and β-agonists improve feedlot performance, efficiency, and carcass characteristics of cattle. The objective of this experiment was to determine the effects of dose and duration of ractopamine hydrochloride (RH) on feedlot performance and carcass characteristics when fed to Holstein steers. A randomized complete block design was used with a 3 × 3 factorial arrangement of treatments with 3 RH doses (0, 300, or 400 mg∙steer−1∙d−1) fed for 3 durations (28, 35, or 42 d). Holstein steers (n = 855; initial body weight [BW] = 448 ± 37 kg) were blocked by BW and randomly allocated to 1 of 9 pens (15 blocks; 9 dose × duration treatment combinations) approximately 72 d before harvest. Weekly pen weights, chute temperament scores, and animal mobility were determined during the RH feeding period. At harvest, carcass data were collected on all steers, and tenderness was measured on steaks from 3 or 4 randomly selected steers from each pen and slice shear force (SSF) was determined on one steak selected from each side of the carcass after aging for 14 or 21 d. For feedlot performance, carcass characteristics, and SSF, no dose × duration interactions were observed (P ≥ 0.11). With increasing RH dose, average daily gain (ADG) and gain-to-feed ratio (G:F) increased linearly (P ≤ 0.01), whereas BW gain increased linearly with RH dose and duration (P ≤ 0.01). Hot carcass weight (P = 0.02) and longissimus muscle (LM) area (P ≤ 0.01) increased linearly with increasing RH dose. The percentage of carcasses in the USDA Yield Grade 2 category increased linearly (P ≤ 0.01) and percentage of carcasses in the USDA Yield Grade 4 category tended (P = 0.08) to decrease linearly as RH dose increased. In the 14-d aged steaks, the percentage of steaks with SSF ≤ 15.3 kg decreased linearly (P ≤ 0.01), whereas the percentage of steaks with ≥20.0 kg SSF increased linearly (P ≤ 0.01) with increasing RH dose. After 21-d aging, there was a tendency (P = 0.06) for a greater percentage of steaks from steers fed RH to have SSF ≥ 20.0 kg (2% of total steaks), but no difference (P ≥ 0.12) in the percentage of steaks with SSF ≤ 19.9 kg. Final chute temperament (P ≥ 0.45) and animal mobility (P ≥ 0.67) scores were not affected by feeding RH. Increasing the dose of RH (300 or 400 mg∙steer−1∙d−1) fed for 28 to 42 d before harvest increased ADG, G:F, hot carcass weight, and LM area when fed to Holstein steers with no negative effects on behavior or mobility. The percentage of steaks classified as not tender improved when steaks were aged for 21 d from steers treated with RH. [ABSTRACT FROM AUTHOR]

Resilience to restricted availability of drinking water was evaluated with 44 Dorper (DOR; initial age = 3.7 ± 0.34 yr), 42 Katahdin (KAT; 3.9 ± 0.36 yr), and 42 St. Croix (STC; 2.7 ± 0.29 yr) sheep from 46 farms in 4 regions of the USA (Midwest, MW; Northwest, NW; Southeast, SE; central Texas, TX). Ad libitum water intake was determined during 2 wk of period 1, with 75% of this amount offered in 2 wk of period 2 and 50% in 5 wk (i.e., 5 to 9) of period 3. Body weight and DMI in week 2 of period 1 and week 9 of period 3 were analyzed with a mixed effects model. There was a breed × period interaction (P = 0.023) in water intake relative to BW (6.17, 6.69, and 7.19 in period 1 and 3.04%, 3.26%, and 3.36% BW in period 3 for DOR, KAT, and STC, respectively; SEM = 0.219). There were 3-way interactions of breed, region, and period in BW and DMI in g/d (P < 0.010). For STC, BW was greater (P < 0.05) in period 3 vs. 1 for all regions (50.1, 47.6, 42.4, and 45.8 kg in period 1 and 51.9, 49.3, 44.5, and 47.7 kg in period 3), whereas there was only a period difference for DOR from the MW and SE (61.4, 66.0, 64.6, and 59.6 kg in period 1 and 60.6, 66.5, 65.7, and 62.4 kg) and for KAT from TX (50.1, 47.6, 42.4, and 45.8 kg in period 1 and 51.9, 49.3, 44.5, and 47.7 kg in period 3 for MW, NW, SE, and TX, respectively; SEM = 2.57). In accordance, DMI by STC was similar (P > 0.05) between periods for all regions (1.25, 1.17, 1.06, and 1.16 kg/d in period 1 and 1.12, 1.08, 1.02, and 1.02 kg/d in period 3), as was also the case for DOR from MW and SE but not from NW or TX (1.54, 1.50, 1.30, and 1.41 kg/d in period 1 and 1.41, 1.13, 1.25, and 1.18 kg/d in period 3) and KAT from TX though not from the other 3 regions (1.47, 1.52, 1.48, and 1.40 kg/d in period 1 and 1.06, 1.15, 1.30, and 1.33 kg/d in period 3 for MW, NW, SE, and TX, respectively; SEM = 0.061). In conclusion, based on BW and DMI with water intake restricted at 50% of ad libitum consumption by individual animals, STC appeared more consistent in display of high resilience to restricted water availability, although DOR from 2 regions and KAT from 1 also were relatively resilient. The results suggest benefit to breed comparisons of inclusion of animals from multiple areas and that environmental conditions of regions may have disparate effects with different breeds of hair sheep. [ABSTRACT FROM AUTHOR]

Our objective was to determine how calffed or yearling finishing systems affect the performance and efficiency of dairy-beef crossbred steers. Dairy-beef hybrid steers were acquired from Land O' Lakes Calf Milk Research Facility at Grey Summit, Missouri at 12-wk (BW/SD) of age and transported to Willard Sparks Beef Research Center (WSBRC). Upon arrival at WSBRC, steers were weighed, vaccinated, treated for parasites, and implanted with 36 mg of zeranol (Ralgro). Alternating groups of steers were placed either directly on finishing diets (FIN) or on high-quality pasture and supplementation for 5 to 6 mo before returning to WSBRC for finishing (GRW/FIN). Steers in FIN were grown on successively higher energy growing diets through d 112, stepping up to a 20% roughage growing diet from d 28 to 112. On d 112, FIN steers were transitioned to a 12% roughage finishing diet. A final 8% roughage finishing was fed to FIN steers from d 224 to slaughter. Steers in FIN were reimplanted with Ralgro on d 56, Component TE-IS (80 mg trenbolone acetate, 16 mg estradiol, and 29 mg tylosin tartrate; Elanco US, Greenfield, IN) on d 112, and Component TE-S (200 mg progesterone, 20 mg estradiol benzoate, 29 mg tylosin tartrate; Elanco) on d 224. Steers in GRW/FIN were returned to WSBRC, weighed, and processed when they reached 312 ± 7.0 kg. Steers in GRW/FIN were implanted with Component TE-IS at the start of finishing, and Component TE-S on d 120. Steers in GRW/FIN were stepped up to the finishing diet when they reached 407 ± 6.0 kg. Finishing diets for the final 28 d for FIN and GRW/FIN included ractopamine hydrochloride at a rate of 300 mg·steer-1·d-1. At WSBRC, steers within each finishing system were sorted by BW into 4 to 5 head pens. Initial and terminal BW were greater (P < 0.01) in steers in the GRW/FIN finishing system. Body weight at reimplant was greater (P < 0.01) for FIN. Steers in the GRW/FIN system were on feed for fewer (P < 0.01) days compared with FIN steers. Average daily gain (ADG) and DMI (kg·steer-1·d-1) were greater (P < 0.01) for GRW/FIN. Steers in GRW/FIN had a greater (P < 0.02) feed:gain ratio than those placed directly into a finishing system. There were no differences (P < 0.10) in USDA Yield Grade, marbling, ribeye area (REA), or back-fat thickness (BFT) between finishing systems. Steers in FIN had a greater (P < 0.01) dressing percentage (DP) and lighter (P < 0.01) hot carcass weight than those for GRW/FIN. Finishing system has an impact on performance and efficiency of dairy-beef hybrid steers, but minimal impact on carcass quality. [ABSTRACT FROM AUTHOR]

The objective was to compare whole cottonseed (WCS) with a more traditional supplement (20% breeder cube; BC) to determine the impacts on animal performance, metabolites, and methane emissions in beef cows. Cows (n = 24) were assigned to 1 of 2 experimental treatments (BC vs. WCS) based on age and body weight (BW). Supplements were fed individually at 0.9, 1.8, or 2.7 kg per day, resulting in 12 animals per supplement treatment and 4 animals per supplementation level within treatment. Two additional cows served as negative controls. Cows were fed 4 days per week, with supplementation levels being prorated at 1.6, 3.2, and 4.8 kg per feeding. Data collection occurred in 28-day intervals through d 84, with a final collection on d 99 after all cows finished calving. An amount fed per d × d interaction for BW change (P = 0.001) was detected. Cattle that were not supplemented (control) or received 0.9 kg per day lost more BW than cows that received 1.8 or 2.7 kg of supplement per day. There was a body condition score (BCS) change interaction for amount fed per d × d (P = 0.009). There was an amount fed per d × d interaction for back fat thickness (BFT; P = 0.02), and a tendency for an effect of amount fed per day on BFT (P = 0.07). There was a tendency for an amount fed per d × d interaction for fecal score (FS; P = 0.09) indicating that cattle receiving different amounts of supplement had varying trends in FS over time. A day effect was also observed for fecal score (P = 0.00003). There were no interactions (P = 0.55), effect of treatment (P = 0.85), or effect of amount fed per d (P = 0.45) for fecal pH. A treatment × amount fed per d × d interaction for plasma glucose concentrations (P = 0.04) was detected. An amount fed per d × d interaction was detected for plasma lactate concentrations (P = 0.01) indicating that cattle receiving different amounts of supplement had different trends in lactate concentrations over time. An effect of amount fed per d on plasma lactate concentrations (P = 0.05) was also observed. A tendency for an amount fed per d × d interaction for plasma urea nitrogen (PUN; P = 0.06) was observed indicating that cattle receiving different amounts of supplement had varying trends in PUN over time. No treatment effect on methane emissions was observed between cows consuming BC and WCS (P = 0.68). This experiment suggests that the supplementation of BC or WCS had minimal impacts on performance, metabolites, or methane emissions, but some interactions existed between supplementation source or level and day. [ABSTRACT FROM AUTHOR]

Respiratory disease in several species can range from subclinical infection to acute death. Bovine respiratory disease (BRD) remains the greatest economic challenge facing the beef industry. Histones are core proteins in chromosomal structure that, when released extracellularly, are cytotoxic and could contribute to exacerbated tissue necrosis during infection. Work in our laboratory demonstrated cattle suffering severe cases of BRD had limited capacity to protect against the cytotoxic effects of extracellular histones, however, the protective mechanism(s) remain unknown. Literature suggests components of the complement system interact with extracellular histones, but the effects on cytotoxic activity of histones is unclear. The objective of the current experiment was to evaluate protective capacity against extracellular histones and complement activity in feedlot heifers and subsequent disease outcomes. Serum samples were collected from 118 heifer calves (BW 229 ± 2.4 kg) at feedlot arrival and evaluated for protective capacity against histone toxicity employing an extracellular histone toxicity assay; and complement activity using a 50% hemolytic complement screening assay. Animals were retrospectively assigned to groups consisting of: calves not requiring treatment with antibiotics for BRD (NT; n = 80) or calves that died from BRD within 1 wk of entering the feedlot (DA; n = 9). Serum from DA animals was less (P < 0.001) protective than NT animals against histone toxicity. Complement activity of DA animals was reduced (P < 0.05) compared to NT animals. Using a ratio of both assays under stringent selection points, the positive predictive value was 75%, and negative predictive value was 94%. Results indicate that cattle predisposed to severe cases of respiratory have impaired complement activity presumably contributing to impaired protective capacity against histone toxicity. Analyzing these functional pathways may provide a novel selection tool against cattle predisposed to severe cases of BRD. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine the effects of replacing hay and dried distillers grains plus solubles (DDGS) with whole cottonseed (WCS) in diets balanced for physically effective neutral detergent fiber (peNDF) on performance, carcass characteristics, and plasma metabolites of finishing cattle. Heifers (n = 103) and steers (n = 104) were blocked by sex and bodyweight (BW) and randomly allocated to pens within block (6 pens per treatment). Pens were randomly allocated to 1 of 2 experimental treatments: a control diet (CON; prairie hay, DDGS, dry-rolled corn, and liquid supplement), and a WCS diet (CTN; WCS, dry-rolled corn, and molasses). A vitamin and mineral supplement and urea were included in both diets at same rate. Data were collected on 14 d intervals through d 56, then every 28 d until harvest. Animals were harvested in 3 different groups based on BW block. Average daily gain (ADG) and gain to feed ratio (G:F) were greater for the CTN treatment overall (P = 0.05), and the CTN treatment tended to have a greater final BW (P = 0.10). Fecal consistency score was greater for CON treatment on d 42, at beginning of the betaagonist feeding period, and at the final collection (P = 0.03). The CTN treatment had a more neutral fecal pH on d 140 and at the final collection (P = 0.01). No treatment × day interaction (P = 0.70) was detected for plasma glucose, lactate, or urea nitrogen (PUN) concentrations. The CON treatment had greater plasma lactate and PUN concentrations (P = 0.01). A day effect was observed for all analyzed plasma metabolites (P = 0.01). This experiment suggests that WCS improves growth performance and feed efficiency when replacing the roughage and byproduct protein and fat source within a finishing diet. [ABSTRACT FROM AUTHOR]

Our objectives were to determine how prefinishing plane of nutrition, season, and breed of beef sire affect performance, efficiency, and carcass attributes of dairy-beef hybrid calves. Dairy × beef hybrid steers (3 to 7 d of age) were maintained on either a moderate plane of nutrition or high plane of nutrition from 0 to 12 wk of age. Calves (n = 211, BW = 122 ± 16 kg) were then transported 689 km to the OSU Sparks Beef Research Center at an average age of 92 ± 1.6 d in four blocks. Calves from predominantly Holstein dairies in the Midwest were sired by Angus (n = 147) or Continental breed (n = 64) sires. Steers were processed on arrival and were sorted by BW within previous treatment into 4 to 5 head pens and fed receiving diets. Steers were transitioned to a grower diet from d 14 to 112. Steers were fed a 12% roughage finishing diet from d-112 to 224. A final 8% roughage finishing diet was fed from d 224 to slaughter with ractopamine hydrochloride (300 mg·steer-1·d -1) included the last 28-d before harvest. Increasing plane of nutrition during the milk replacer and starter feeding period increased (P = 0.03) initial BW at arrival and through d 84, but was not affected (P = 0.08) thereafter. Calves received during the winter and spring were heavier (P < 0.01) on arrival through d 168 and at harvest and gained BW faster during the growing phase and final finishing phase than steers received during the summer. Steers sired by Angus sires were heavier throughout finishing (P < 0.01) and gained BW more rapidly (P < 0.01) than steers sired by Continental breeds. Breed of sire and season have a large impact on performance of finishing dairy × beef hybrids. [ABSTRACT FROM AUTHOR]

Four years of feedlot performance and carcass characteristics were pooled on spring-(SPRING) and fall-(FALL) born steers (n=460) into a mixed model to evaluate the effects of calving season, sire breed (Angus [AN], Charolais [CHAR] or Hereford [HER]) and their interaction on feedlot performance and carcass traits. Initial and final BW, DOF, ADG, DMI, and G:F were evaluated as performance measures and HCW, YG, FT, REA, and MS were collected at harvest. There was no season by breed interaction for entry or final BW (P >0.05). SPRING steers (400.2 kg, 686.4 kg) weighed more than FALL (350.9 kg, 668.3 kg) upon entering and leaving the feedyard (P< 0.001). CHAR weighed 14.3 kg less than AN upon feedlot entry (P=0.01) although final BW did not differ by breed (P >0.05). SPRING steers (21.8 kg/d) consumed more feed than FALL steers (18.8 kg/d; P=0.002), but there was no difference in gain:feed due to calving season nor sire breed (P=0.575). A calving season by sire breed interaction was present for ADG and DOF (P=0.014). FALL AN (1.70 kg/d) and FALL HER (1.80 kg/d) gained more than FALL CHAR (1.55 kg/d;P< 0.001) and FALL AN were fed over a shorter period than FALL CHAR and FALL HER (P=0.006). However, average daily gain of SPRING calves did not differ by breed (P >0.05). There was a tendency for FALL (400.9 kg) steers to have lighter carcasses than SPRING steers (407.9 kg; P=0.068). HER carcasses were 18.0 kg heavier than AN carcasses (P< 0.001), but did not differ from CHAR (P=0.13). CHAR had larger REA (93.5 cm2) than both AN (87.7 cm2) and HER steers (88.5 cm2;P=0.001). Fall-born steers had less YG than spring-born steers (P< 0.042). Feedlot performance was generally less for fall-born steers finished during the winter months. Under these conditions, numerous performance and carcass traits were influenced by the interaction of breed and season. [ABSTRACT FROM AUTHOR]