The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on health, growth performance, and carcass characteristics of high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n=300) and steers (n=84; BW = 220 ± 16.2 kg) were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) placebo control (CON); 2) 13 g/animal daily of B. subtilis PB6 (CST); 3) 450 ppb DM chromium propionate (CHR); and 4) 13 g/animal daily of B. subtilis PB6 and 450 ppb DM chromium propionate (CST+CHR). Treatments were top dressed in feed bunks daily using 0.45 kg/animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models. During the receiving period, DMI increased (P ≤ 0.03) for CST during each interim period. Overall receiving period daily DMI was 0.35 kg/animal greater for CST (P = 0.01). Cattle fed CST had greater (P ≤ 0.06) BW on days 14, 28, and 56. Likewise, ADG was improved for CST from day 0 to 14 (P = 0.04) and for the overall receiving period (day 0 to 56; P = 0.04). From days 0 to 14, CST tended (P = 0.08) to increase G:F. During the finishing period, CHR reduced (P = 0.02) final BW and ADG (day 56 to final; P = 0.01) and ADG was less for CHR over the entire feeding period (day 0 to final; P = 0.03). Main effect of both CST (P = 0.02) and CHR (P = 0.03) decreased the overall treatment rate for bovine respiratory disease (BRD), and CST reduced overall antimicrobial treatment cost by $3.50 per animal compared to CON (P = 0.03). Hot carcass weight decreased (P = 0.01) in cattle fed CHR. Percentage of edible livers tended to increase (CST × CHR; P = 0.08) in the CST treatment. Feed intake and growth performance outcomes during the receiving period were improved by CST but not CHR supplementation. However, both CST and CHR supplementation decreased BRD morbidity rate. During the finishing period, performance and HCW were reduced in cattle supplemented with CHR.
The objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on health, performance, and blood parameters in high-risk beef calves during a 56-day receiving period. Four truckload blocks of crossbred beef calves (n = 384; BW=220±16.2 kg) were assigned randomly to treatments arranged in a 2 × 2 factorial. The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) placebo control (CON); 2) 13 g/animal/d Bacillus subtilis PB6 (CLOSTAT®, Kemin Industries; CST); 3) 1 g/animal/d Cr propionate (KemTRACE® Chromium, Kemin Industries; CHR); and 4) CST+CHR. Treatments were top dressed in feed bunks daily using 0.45 kg/animal/d ground corn carrier. Blood samples were collected on days 0, 14, 28, and 56 for analysis of serum chemistry and complete blood count variables from a pen subset (n = 2/pen). Data were analyzed using MIXED and GLIMMIX procedures of SAS. The DMI was increased for CST during each interim period (P ≤ 0.03) and overall DMI was increased by 0.78 lb/animal/d for CST (P = 0.01). The CST supplemented cattle had greater BW on days 14, 28, and 56 (P ≤ 0.06). Likewise, ADG was improved for CST from day 0 to 14 (P = 0.04) and for the overall receiving period (P = 0.04). Main effects of CST (P = 0.02) and CHR (P = 0.03) decreased the percentage of calves treated for bovine respiratory disease (BRD). Morbidity was 28.0 and 39.9% for cattle with and without CST supplementation and 28.6 and 39.3% for cattle with and without CHR supplementation, respectively. Cattle fed CHR had increased (P ≤ 0.04) total leukocytes, neutrophils, serum aspartate aminotransferase and less (P = 0.02) serum calcium. Performance was improved by CST and BRD morbidity was less for CST and CHR.
The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on serum chemistry, complete blood count, and fecal Salmonella spp. count in high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n=300) and steers (n=84; total n=384; average initial BW = 220 ± 16.2 kg) were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. Blood samples were collected from two bulls nearest the median BW on arrival in each pen (n=96) and fecal samples were collected from cattle in block 3 (n=96). The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) negative control (CON); 2) 13 g/animal daily of prepared B. subtilis PB6 product (CST); 3) 450 ppb DM chromium propionate (CHR); and 4) 13 g/animal daily of prepared B. subtilis PB6 product and 450 ppb DM chromium propionate (CST+CHR). Treatments were top dressed in feed bunks daily using 0.45 kg/animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models with repeated measures. Day affected all serum chemistry variables (P ≤ 0.03) except total CO2 (P = 0.34) and all complete blood count variables during receiving (P ≤ 0.02) except percentage basophils (P ≥ 0.12). During the overall receiving period, serum calcium was decreased (P = 0.02) by CHR. Cattle fed CHR had greater total leukocyte count (P = 0.04) and neutrophil count (P = 0.02) during the overall receiving period. Fecal Salmonella spp. count was markedly reduced in cattle fed CST on day 28 (P = 0.01) and overall (P = 0.07). Overall, these data provide metabolic and hematologic insight into the unique challenges presented by lightweight, high-risk feeder cattle. Notably, CST was found to be effective in mitigating fecal enumeration and presumably replication of Salmonella spp. in the gastrointestinal tract.
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