The effects of receiving diet roughage inclusion on performance, health, and serum metabolite characteristics of newly received beef calves.

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 ±â€…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 ±â€…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.

The effects of varying levels of trace mineral supplementation on performance, carcass characteristics, mineral balance, and antibody concentrations in feedlot cattle.

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.

Evaluation of ruminal degradability and metabolism of feedlot finishing diets with or without cotton byproducts.

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.

Effects of utilizing cotton byproducts in a finishing diet on beef cattle performance, carcass traits, fecal characteristics, and plasma metabolites.

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.