Search

Our objective was to determine the effect of calf-fed or yearling finishing systems on the performance 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-weeks 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). Once GRW/FIN steers reached 312 ± 7 kg, the steers were returned to WSBRC, weighed, and processed. At WSBRC, steers within each finishing system were sorted by BW into 4 to 5 animal pens. Steers in FIN were re-implanted with Ralgro on d 56, Component TE-IS (80-mg trenbolone acetate,6-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 implanted with Component TE-IS at the start of finishing, and Component TE-S on d 20. Steers in FIN were grown on successively greater energy growing diets through d 112, stepping up to a 20% roughage growing diet (18.4% CP and 2.4 Mcal NEg/kg from d 28 to 112. On d 112, FIN steers were transitioned to a finishing diet consisting of 12% roughage, 12% crude protein, and 1.3 Mcal NEg/kg. A final finishing diet (8% prairie hay, 20% Sweet Bran and 62% dry-rolled corn) was fed to FIN steers from d 224 to slaughter. Steers in GRW/FIN were stepped up to the finishing diet when they reached 407 ± 6 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. 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 (HCW) 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.

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.

Our objectives were to determine how pre-finishing 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.

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.

Two experiments (EXP1 and EXP2) evaluated the effects of NutraGen (NG) on calf health following exposure to bovine viral diarrhea virus (BVDV) on d -3 and Mannheimia haemolytica (Mh) infection on d 0. For each EXP, steers (BW = 251 ± 38.2 kg) were randomly allocated to 1 of 3 treatments (TRT). Treatments included a placebo (CON; EXP1 n = 5; EXP2 n = 5), a placebo fed from d -18 to d -3 followed by NG fed from d -3 to d 28 (CHLG; EXP1 n = 5; EXP2 n = 6), and NG fed from d -18 to d 28 (PREC; EXP1 n = 6; EXP2 n = 5). There was no treatment by time interaction (TRT×TME) or TRT effect for rectal temperatures (RT) or clinical scores (CS) in EXP1 or CS in EXP2 (P ≥ 0.26). There was a TRT×TME for respiration rates (RR) during the first 24 h following Mh infection (P = 0.04), and a tendency for a TRT effect from d -3 to d 14, and overall in EXP1 (P ≤ 0.10). There was a tendency for a TRT×TME for RT from d -3 to d 14 in EXP2 (P = 0.04). There was a TRT effect for RR from d -3 to d 14 and overall in EXP2 (P ≤ 0.05). There was a TRT×TME for leukocytes during the first 24 h following Mh infection in EXP1 (P = 0.03) and overall in both EXP (P ≤ 0.001). There was no TRT×TME or TRT effect for neutrophils (NEU), lymphocytes (LYM), or NEU:LYM in EXP1 (P ≥ 0.19); however, there were multiple TRT×TME and TRT effects for NEU, LYM, and NEU:LYM in EXP2 (P ≤ 0.05). These experiments suggest that NG has the potential to alter clinical and cellular responses during a bovine respiratory disease challenge.

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.

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 beta-agonist 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.

Trace mineral (TM) supplementation is critical for optimal performance and health. The objective was to determine the effects of varying levels of TM supplementation on feedlot cattle TM status and antibody concentrations. Angus steers (n = 240; BW = 291 kg ± 27.4) were stratified by arrival BW and source and assigned to 1 of 4 treatments (12 pens/treatment; 5 steers/pen). Treatments included a negative control (CON) in which cattle received no TM supplementation, a requirement treatment (1X) in which cattle received added TM at 2016 Nutrient Requirements of Beef Cattle required levels, a 2 times requirements (2X), and a 4 times requirements (4X) treatment. Selenium was included at 0.1, 0.2, and 0.3 mg/kg for 1X, 2X, and 4X respectively. Treatments were chosen based on reported TM supplementation levels from the 2015 Feedlot Consulting Nutritionist Survey. One steer was chosen at random from each pen to be evaluated for serum and liver TM status and antibody concentrations to respiratory viruses. There was 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. 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 < 0.0019). Concentrations for individual TM had different trends over time, however, all reported values were within normal ranges. Serum Zn was greater at harvest (P = .02). There was an effect of time on Bovine Viral Diarrhea Virus Type 1A, Bovine Herpesvirus Type 1, Bovine Parainfluenza 3 virus antibody titer concentrations (P < 0.0001).

Cotton byproducts can be an economical source of protein, fat, and fiber in cattle finishing diets. The objectives of this study were 1) to assess the effects of including whole cottonseed (WCS) and cotton gin trash (CGT) in finishing diets on in situ ruminal degradability and 2) to determine the effects of including cotton byproducts in a finishing diet on rumen fluid pH, lactate, and volatile fatty acid concentrations. Six ruminally cannulated steers were used in a crossover design. Treatments included a control diet (CON; 7% prairie hay [PH], 15% Sweet Bran, 67.25% rolled corn, and 5% liquid supplement) and a cotton byproduct diet (CTN; 7% CGT, 15% WCS, 72.25% rolled corn, and 5% water). Both diets included 0.75% urea and 5% dry supplement. In situ bags containing individual diet ingredients and whole diet samples were incubated in the rumen for up to 96 h. Rumen fluid samples were collected over a 24-h period. No treatment × substrate interactions were detected for any fraction of dry matter (DM) or organic matter (OM) degradability for individual ingredients or whole diets (P ≥ 0.14). The A, B, and C fractions, disappearance rate (Kd), and effective degradability of DM and OM differed between diet ingredients (P ≤ 0.04) but were not different between CON and CTN substrates (P ≥ 0.25). A treatment × substrate interaction (P = 0.04) was detected for the effective degradability of neutral detergent fiber (NDF) of CGT and PH but there was no interaction for other fractions (P ≥ 0.27). The A fraction of NDF was greater (P < 0.001) for CGT than PH; however, the B fraction of NDF tended to be greater (P = 0.08) for PH than CGT. No differences (P ≥ 0.37) were detected for the % NDF disappearance at 48 h between CON and CTN substrates. A tendency for a treatment × substrate interaction (P = 0.10) was observed for the effective degradability of starch among diets; however, when the CON substrate was incubated in steers consuming the CON diet, effective degradability of starch was not different (P = 0.84) from when the CTN diet was incubated in steers consuming the CTN diet. There was no treatment × time interaction or treatment effect for rumen pH; however, there was a time effect (P = 0.03). Steers consuming the CTN diet had greater molar proportions of acetate and decreased molar proportions of propionate compared with CON steers (P < 0.01). This experiment suggests that there are minimal differences between the digestibility of finishing diets containing cotton byproducts and those comprised of traditional finishing diet ingredients.

As climate change progresses, it is expected that water availability for livestock production will be challenged due to competition from human population growth and use by other agricultural sectors. The objective of this study was to evaluate differences in animal performance and health between feedlot steers with differing water use efficiencies. Four groups of steers from numerous sources (n = 469) were randomly allocated to 2 body weight (BW) blocks. Individual feed and water intake (WI) were measured daily using an Insentec RIC feeding system. Steers had ad libitum access to feed and water for 70 d (BAS). After a 28 d step-down period, steers were maintained at 50% of ad libitum water consumption for 42 d (RST) while feed continued to be offered ad libitum. Based on average daily water intake during BAS, steers were sorted into low, medium, or high-water use efficiency (LWE, MWE, or HWE) using k-means clustering. Every 14 d BW was collected in addition to blood samples for complete blood counts. Body weight was used to evaluate ADG and G:F. Data were analyzed using the GLIMMIX procedure of SAS with the model statement including effects of water use efficiency, day, and the interaction. Body weights were greater in HWE than MWE and LWE at the end of BAS and RST (P < 0.01). Steer ADG and G:F were greater in HWE compared to MWE and LWE (P < 0.01)during BAS, but not different during RST (P > 0.54). Hematocrit and red blood cell counts initially increased during water restriction step down, and then returned to normal levels (P < 0.01); these values were also greater in HWE compared to MWE and LWE (P < 0.01). All steers adapted to limited water access similarly and the degree of health differences had little clinical significance.

Morbidity and mortality in newly weaned calves resulting from bovine respiratory disease (BRD) continue to be the most significant problems facing the beef industry. Morbidity attributed to BRD accounts for approximately 75% of total feedlot morbidity. Several experiments have documented the economic impacts of BRD. Direct costs attributable to BRD include death loss, treatment and labor costs, and prevention costs, while indirect costs associated with BRD include decreased growth performance and feed efficiency, increased days on feed, and decreased carcass merit and market value. In recent years, cattle treated for BRD have returned $50 to $250 less per head at harvest than cattle never treated for BRD. Best management practices for newly weaned calves vary depending on a multitude of factors including: season of year calves are purchased, calf genetics, length of time in the marketing and transport channels, previous management and vaccination programs, and other factors. In general, calves purchased directly from a ranch have fewer health problems than calves purchased through auction markets. The longer a calf is in the marketing chain, the more likely health problems will be encountered. Calves that have spent several days in the marketing chain may develop clinical BRD before or very soon after arrival, whereas cattle with less time in the marketing chain may get sick later (2 to 4 wk), due to the length of time it takes for BRD to develop. On or before arrival, calves should be given a risk score (high, medium, or low) that relates to the quantity and magnitude of stress they have encountered and the probability they will develop BRD. High-risk calves typically will have been recently weaned, received no vaccinations, not been castrated or dehorned, been commingled, and moved through an auction market. Low-risk calves will often originate from a single source and will have gone through a preconditioning program that includes vaccination, castration, dehorning, weaning, and potentially feed bunk adaptation. Variation exists within risk category, so the preliminary assessment should be combined with visual observation on arrival as additional health assessments and feed intake information becomes available. Cattle managers should adjust management strategies based on risk category to meet the perceived needs of individual lots of cattle to improve the health and well-being of newly weaned calves.

The objective of this experiment was to determine the effects of dietary inclusion of lasalocid in combination with zeranol implants on the performance and carcass characteristics of hair sheep. Thirty wether hair lambs (BW = 25.8 + 4.6 kg) were stratified by BW and BCS and randomly assigned to 1 of 2 experimental treatments in a randomized complete block design. The treatments included no implant or ionophore (CON); and the experimental treatment, receiving the ionophore lasalocid (Bovatec® 91; Zoetis, Kalamazoo, MI) and anabolic zeranol implants (Ralgro®; MSD Animal Health, Spartan, RSA; LZ). Lambs on the LZ treatment received 12 mg of zeranol on d 0, 56, and 112, unless lambs were harvested prior to day 112, and consumed an average of 35 mg per day of lasalocid. Lambs had ad libitum access to feed and water throughout the experiment and were housed in individual, slatted floor pens. Performance data were collected on d 0, 14, 28, 56, 84, and at harvest. After d 84, harvest dates were selected and lambs were harvested by block based on proximity to ideal harvest weight and fat thickness. Lasalocid in the diet combined with zeranol implants increased final BW by 14.2% in comparison to CON (P < 0.01). Overall ADG was increased by 36.2% (P < 0.01), and overall G:F was improved by 24.4% for LZ when compared to CON (P = 0.01). There was no difference in overall DMI between treatments (P = 0.13). Hot carcass weight (HCW; P < 0.01), and loin eye area (LEA; P < 0.01) were also greater for the LZ treatment. Dietary inclusion of lasalocid in combination with zeranol implants improved overall BW, ADG, and feed efficiency as well as HCW and LEA in hair sheep.

The objective of this experiment was to examine the effects of fly control strategies on fly abundance, fly avoidance behaviors, and animal performance in a feedlot setting. Angus bulls (n = 64; BW = 281 ± 36.2 kg) and steers (n = 36; BW = 475 ± 40.4 kg) were blocked by sex and BW and assigned to 1 of 4 experimental treatments in a randomized complete block design (7 pens/treatment; 4 bulls/pen; 3 steers/pen). Treatments included: control (CON; no fly control), abamectin, piperonyl butoxide, and zetacypermethrin insecticide tags (FT; Tri-Zap®, Y-Tex Corporation, Cody, WY), permethrin and piperonyl butoxide pour on (PO; Permectrin® CDS, Bayer Animal Health, Shawnee Mission, KS), or a garlic-powder top dress (GR) administered at 0.28 g •-1 animal •-1d. The experiment was conducted between June and September. Horn and stable fly abundance (FA) and fly avoidance behaviors (FAB; i.e. tail-flicks, stomping, head-tossing) were recorded by trained personnel. Both FA and FAB were recorded once/wk on days with similar temperatures, humidity, wind speed, and without precipitation based on Oklahoma Mesonet data (Stillwater site). There was a tendency for a treatment × time interaction for horn FA with differences in treatments occurring at wk 1, 2, 8, and 14. There was no treatment × time interaction for stable FA or FAB, however both were affected by time (P < 0.001). There were no differences in final BW (P = 0.34), overall ADG (P = 0.30), overall DMI (P = 0.53), or overall G:F (P = 0.39). There was a tendency (P ≤ 0.10) for GR to have decreased BW on d 28 and decreased ADG from d 0 to 28 compared to FT and PO. There was also a tendency (P = 0.09) for decreased DMI from d 0 to 56 for GR compared to CON and FT. Overall FA was less than expected (mean = 1 to 17 flies/animal) throughout the experiment and overall animal performance was unaffected by fly control strategy.

Increased cotton production in the Southwestern United States has increased the availability of cotton byproducts for use in cattle diets. The objective of this experiment was to evaluate the inclusion of cotton byproducts in feedlot finishing diets on the performance, carcass traits, fecal characteristics, and plasma metabolites of steers. Crossbred beef steers (n = 64; BW = 318 ± 12.3 kg) were assigned to 1 of 2 experimental treatments in a randomized complete block design (8 pens per treatment; 4 steers per pen). Treatments included a control (CON) diet, which included prairie hay, Sweet Bran, rolled corn, and a corn steep and molasses-based liquid fat supplement, and a cotton byproduct (CTN) diet, which included cotton gin trash, whole cottonseed, rolled corn, and water. Both diets contained urea and dry supplement. Over the entire feeding period, DMI (P = 0.04) was greater for CTN steers than CON steers with no difference in the gain to feed ratio (P = 0.86) between treatments. The CTN steers tended to have heavier final BW (P = 0.09) and greater overall average daily gain (P = 0.08). The CTN steers had heavier hot carcass weight (P = 0.02) and greater fat thickness (P = 0.03) than CON steers, but marbling score and rib eye area were not different between treatments (P ≥ 0.64). Steers fed the CON diet tended to have a lower yield grade (P = 0.07), less kidney, pelvic and heart fat (P = 0.09), and decreased dressing percentage (P = 0.10) than CTN steers. Liver scores did not differ (P ≥ 0.17) between treatments. Fecal consistency scores were decreased for CTN steers on day 56 (P = 0.03) and fecal pH tended to be greater for the CTN steers on day 28 (P = 0.09) compared with CON steers, but neither differed during other periods (P ≥ 0.18). A treatment × day interaction (P = 0.04) was detected for plasma urea nitrogen (PUN) concentrations, where PUN concentrations differed between treatments only on days 28 and 56. On both days 28 and 56, CTN steers had lower PUN concentrations (P = 0.03, P = 0.002, respectively). No treatment × day interaction was detected for plasma glucose or lactate concentrations. A day effect was observed for both metabolites (P < 0.01). Results from this experiment suggest that cotton byproducts can be effectively used as a source of fiber, fat, and protein in feedlot rations without adverse effects on performance or carcass characteristics.

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.

The objective of this experiment was to determine the effects of 4 levels of trace mineral supplementation on feedlot cattle. Two hundred and forty Angus crossbred steers (n = 48, BW = 291 ± 27 kg) 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). Cattle went through a 35 d depletion period prior to the administration of treatments where cattle received a supplement that included zero trace minerals and was formulated to meet or exceed other nutrient requirements not met by the ration. Cattle were administered treatments after transition to the finishing ration. The treatments included a negative control (CON) which contained no added trace minerals, a requirement treatment (1X) in which cattle received added trace minerals at requirement levels indicated by NASEM (Co 0.15 mg/kg, Cu 10 mg/kg, Fe 50 mg/kg, I 0.5 mg/kg, Mn 20 mg/kg, Se 0.1 mg/kg, Zn 30 mg/kg; NASEM 2016), a 2 times requirement levels (2X) treatment, and a treatment at four times requirement (4X) levels recommended by the NASEM. Iron was kept constant at 50 mg/kg for 1X, 2X, and 4X treatments. Due to feeding laws, Selenium was included at 0.1, 0.2, and 0.3 mg/kg for 1X, 2X, and 4X respectively. Treatment levels were chosen based on the 2015 Feedlot Consulting Nutritionist Survey. There was no difference in BW, ADG, overall DMI and G:F over the course of the experiment (Linear P ≥ 0.12; Quadratic P ≥ 0.17; CON vs Supplements P ≥ 0.47) There was no difference in marbling score, yield grade, back fat, REA, HCW, or dressing percentage between treatments (Linear P ≥ 0.23; Quadratic P ≥ 0.36; CON vs Supplements P ≥ 0.30). In conclusion, the lack of or addition of supplemented trace minerals at or above indicated requirement levels has no effect on cattle performance or carcass characteristics.

Bovine respiratory disease (BRD) is the most common and economically detrimental disease of beef cattle during the postweaning period, causing the majority of morbidity and mortality in feedlots. The pathogenesis of this disease often includes an initial viral infection, which can predispose cattle to a secondary bacterial infection. The objective of this experiment was to determine the effects of timing of an intratracheal (MH) challenge relative to 72 h of natural exposure to bovine viral diarrhea virus (BVDV) type 1b persistently infected (PI) calves on performance, serum antibody production, total and differential white blood cell (WBC) count, rectal temperature, clinical severity score (CS), and haptoglobin (Hp). Steers ( = 24; 276 ± 31 kg initial BW) were randomly allocated to 1 of 3 treatments (8 steers/treatment) in a randomized complete block design. Treatments were steers not exposed to calves PI with BVDV 1b and not challenged with MH (CON), steers intratracheally challenged with MH 84 h after being exposed to calves PI with BVDV 1b for 72 h (LateCh), and steers intratracheally challenged with MH 12 h after being exposed to calves PI with BVDV 1b for 72 h (EarlyCh). Performance (ADG, DMI, and G:F) was decreased ( < 0.001) for both EarlyCh and LateCh from d 0 to 4. From d 5 to 17, LateCh appeared to compensate for this lost performance and demonstrated increased ADG ( = 0.01) and G:F ( = 0.01) compared with EarlyCh. Both EarlyCh and LateCh had decreased platelet counts ( < 0.001) compared with CON. Antibody concentrations of BVDV and MH were higher ( < 0.05) for both EarlyCh and LateCh compared with CON. Rectal temperature, CS, and Hp increased ( < 0.001) across time from h 4 to 48, h 4 to 36, and h 8 to 168, respectively. Within 24 h of MH challenge, WBC and neutrophil concentrations within the blood increased whereas lymphocyte concentrations decreased. The timing of BVDV exposure relative to a MH challenge appears to influence the CS and acute phase response associated with BRD. As typical beef cattle marketing channels allow for variation in the timing of respiratory pathogen exposure, understanding the physiological changes in morbid cattle will lead to improved management of BRD.

Research has indicated that trace mineral (TM) supplementation may alter immune function and reduce morbidity associated with bovine respiratory disease. The objective of this experiment was to determine the influence of dietary Cu, Mn, and Zn supplementation on the performance, clinical signs, and TM balance of calves following a bovine viral diarrhea virus (BVDV) and (MH) combination respiratory pathogen challenge. Steers ( = 16; 225 ± 20 kg BW) from a single ranch were processed, weaned, and randomly pairwise assigned to either the TM-supplemented (MIN) or the control (CON) experimental treatments. The MIN calves received an additional 150 mg of Cu, 130 mg of Mn, and 320 mg of Zn daily and the CON calves received the basal diet with no additional Cu, Mn, or Zn supplementation. The basal diet contained sufficient Mn and Zn but inadequate Cu based on published nutrient requirements. After 46 d on the experimental treatments, all calves were naturally exposed to a heifer persistently infected with BVDV type 1b for 4 d and then subsequently intratracheally challenged with MH. Data were analyzed using the GLIMMIX procedure of SAS with sampling time serving as a repeated measure and calf serving as the experimental unit. The respiratory challenge was validated via increased BVDV type 1b antibody concentrations, MH whole cell and leukotoxin antibody concentrations, rectal temperatures (TEMP), and subjective clinical severity scores (CS). Calf performance ( ≥ 0.48) was not affected by TM supplementation. Mineral supplementation also did not impact the CS or TEMP of calves ( ≥ 0.53). There was a treatment × time ( < 0.001) interaction observed for liver Cu concentrations. The concentrations of Cu, Mn, Zn, and Fe within the liver; Cu, Mn, and Zn within the muscle; and Cu, Zn, and Fe within the serum were all impacted by time ( ≤ 0.03). Calves receiving the MIN treatment had greater ( < 0.01) liver Cu and Mn concentrations compared with CON calves. In contrast, serum Cu and Fe concentrations were increased ( ≤ 0.05) in CON calves compared with MIN calves. Mineral supplementation did not impact TM concentrations within the muscle ( ≥ 0.38). The supplementation of Cu, Mn, and Zn can improve the Cu and Mn status within the liver and serum of calves in response to a BVDV and MH challenge. When Cu is supplemented to calves receiving a marginally Cu-deficient diet, Cu status within the body is significantly improved.

The inclusion of wet distillers grains plus solubles (WDGS) in feedlot diets has become a common practice in many regions of the United States due to the expanded production of byproducts and fluctuating corn prices related to ethanol production and other factors. In addition, societal concerns over the continued use of antimicrobials in agriculture production combined with an enhanced interest in disease and pathogen prevention in the food supply have led to an increased interest in use of direct-fed microbials (DFM) in growing and finishing cattle. Direct-fed microbials have been shown to improve ADG and feed efficiency, alter ruminal fermentation, and decrease fecal shedding of potential harmful pathogens in feedlot cattle in some experiments. The objective of this experiment was to evaluate the effects of WDGS inclusion with or without a DFM containing (1 × 10 cfu ∙ heifer ∙ d) combined with (1 × 10 cfu ∙ heifer ∙ d) on the performance, carcass characteristics, and O157:H7 shedding in feedlot heifers. In early August, 288 crossbred heifers (initial BW = 295 ± 28 kg) were assigned to 1 of 4 treatments (12 pens per treatment; 6 heifers per pen) in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. Body weights and fecal grab samples were obtained at approximately 28-d intervals throughout the experiment. Across the feeding period, heifers fed 30% WDGS tended ( = 0.09) to have greater ADG and had greater carcass-adjusted ADG ( = 0.05) compared with heifers fed dry-rolled corn (DRC). Dry matter intake was not affected ( = 0.65) by diet, although carcass-adjusted G:F tended ( = 0.10) to be improved for heifers fed WDGS. Heifers fed 30% WDGS tended ( ≤ 0.10) to have greater fat thickness at the 12th rib, lower marbling scores, and higher yield grades. The inclusion of . combined with . in the diet had no effect ( > 0.10) on performance or carcass merit in the present experiment. The incidence of O157:H7 throughout the experiment was low, with only 18 positive samples across all sampling periods. Neither WDGS inclusion nor the inclusion of . combined with . in the diet had any effect ( > 0.10) on O157:H7 shedding in this experiment. Feeding 30% WDGS to feedlot heifers improved animal performance compared to the DRC-based control diet.

Automatic feeding systems are being used more frequently to understand individual cattle behavior and intake variation when cattle are group housed. The objective of this experiment was to evaluate if bunk preference exists, and if so, how bunk preference affects performance, intake, or efficiency of feedlot steers. Angus steers (n = 123; initial BW = 293 ± 33.8 kg) were blocked by BW and sire and assigned to 1 of 4 pens, each containing 6 automated feed bunks (Insentec RIC; Hokofarm Group, Marknesse, Netherlands), in a randomized complete block design. Steers were fed a common diet and free to consume feed from any bunk within the pen without restriction. A steer’s preferred bunk was defined as the bunk from which the most feed was consumed. In any week, 80% of steers consumed less than 29% of that week’s total feed intake from the preferred bunk, indicating no strong preference for a specific bunk. The maximum weekly feed intake consumed from a preferred bunk was 57%. Further, the percentage of intake from the preferred bunk did not affect overall ADG, feed intake, or G:F (P > 0.64). These results suggest that a few steers may have a relatively strong preference for a specific feed bunk, however this preference was not associated with performance, intake, or efficiency. Researchers can design experiments (at a stocking density of 5 steers per bunk) that restrict or alter an individual animal’s access to any specific bunk, because such access, or lack of access, does not alter the animal’s performance or feed intake.