Effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on clinical health, growth performance, and carcass traits of high-risk cattle during the feedlot receiving and finishing periods1

Abstract

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.

Evaluation of Bacillus subtilis PB6 on feedlot phase growth performance, efficiency of dietary net energy utilization, and fecal and subiliac lymph node Salmonella prevalence in spring placement yearling beef steers fed in southeastern South Dakota1,2,3

“…This is similar to what has been reported by Smock et al (2020a) who noted no improvements in cumulative growth performance responses in steers when B. subtilis PB6 was fed to high-stressed feeder steers. Alternatively, Smock et al (2020a) noted an improvement in ADG and DMI during the initial 56-d feedlot-receiving phase when B. subtilis PB6 was supplemented to high-stressed feeder steers. Estimated dietary NE based on growth performance was in close agreement with the expectation based on diet formulation ( P ≥ 0.46).…”

“…Finally, there were no treatment effects ( P ≥ 0.54) for the prevalence of abscessed livers in this experiment. These findings are very similar to Smock et al (2020a) , who indicated that the distribution of USDA YG and quality grade or condemned livers were not influenced by the supplementation of B. subtilis PB6 to finishing beef steers.…”

“…In transit-stressed steers from the southeastern United States transported and fed in Oklahoma, the supplementation of B. subtilis PB6 (CLOSTAT, Kemin Industries) had no influence on HCW, dressing percentage, RF, REA, USDA marbling score, or calculated YG ( Kemin, 2018 ). Smock et al (2020a) detected no differences for HCW, dressing percentage, USDA marbling scores, RF, REA, or calculated YG when B. subtilis PB6 was fed to finishing steers. The distribution of USDA low choice grade tended ( P = 0.08) to be greater for CLO compared to CON steers.…”

Impacts of a post-transport/pre-processing rest period on the growth performance, anthelmintic efficacy, and serum metabolite changes in cattle entering a feed yard

“…By d 14, we saw a linear decrease in DMI as calves were processed beyond 6-h. Additionally, cattle were not allotted to their experimental pens until all calves had been processed at 48-h post-arrival. Each receiving pen provided free-choice hay and water, but no concentrate was provided until all cattle had been processed at 48-h. Much work has been done assessing how this time frame impacts the digestion and rumen function of cattle and their ability to adapt to the receiving diet ( Duff and Gaylean, 2007 ; Gilbery et al, 2007 ; Smock et al, 2020 ). Limited ruminal fermentative capacity (RFC) is a potential factor responsible for limited feed intake in cattle deprived of feed due to transport.…”

Galyean Appreciation Club Review: revisiting nutrition and health of newly received cattle—what have we learned in the last 15 years?

“…The 0.3 mg/kg diet resulted in the lowest BRD morbidity (7.5% vs. 25.9% for the control diet). Smock et al (2020) compared the effects of a Bacillus subtilis PB6 direct-fed microbial and 450 ppb chromium propionate or the combination of the two with a control diet in 384 bull and steer calves (220 kg BW) during a 56-d receiving period. The direct-fed microbial, alone or in combination with Cr, increased DMI for the receiving period compared with other treatments, which was associated with increased ADG.…”