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 feed in s

Authors: GUBBELS, ERIN - South Dakota State University; Broadway, Paul; UNDERWOOD, KEITH - South Dakota State University; RUSCHE, W - South Dakota State University; WALKER, J - South Dakota State University; Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; LAFLEUR, DOUG - Kemin Industries, Inc; HERGENREDER, JERILYN - Kemin Industries, Inc; SMITH, ZACHARY - South Dakota State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/2021
Publication Date: 3/1/2022
Citation: Gubbels, E.R., Broadway, P.R., Underwood, K.R., Rusche, W.C., Walker, J.A., Sanchez, N.C., Carroll, J.A., Lafleur, D., Hergenreder, J.E., Smith, Z.K. 2022. 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 Dakota. In: Proceedings of the 2021 Plains Nutrition Council Spring Conference, April 8-9, 2021, San Antonio, TX. p. 102

Interpretive Summary:

Technical Abstract: The objective of this study was to determine the influence of Bacillus subtilis PB6 administration in yearling feedlot steers on growth performance, efficiency of dietary net energy (NE) utilization, carcass trait responses, and Salmonella prevalence. Yearling crossbred beef steers [n = 238; initial shrunk body weight (BW) = 884 ± 46.6 lb] were used during a 140-d finishing period at the Southeast Research Farm in Beresford, SD. Steers were allotted to 1 of 24 pens (n = 9 to10 steers/pen) and assigned to 1 of 2 dietary treatments (12 pens/treatment): CON (no probiotic) or CLO (0.5 g·steer·d-1 of the B. subtilis PB6 active microbial (CLOSTAT 500, Kemin Industries, Des Moines, IA). Steers were fed a common finishing diet that consisted of dry-rolled corn, modified distillers grains plus solubles, corn silage, and liquid supplement (provided vitamins and minerals to exceed nutrient requirements and provided [DM basis] 450 ppb chromium propionate and 30 g/ton of monensin sodium). The diet also provided 12.5% crude protein, 93.0 Mcal/lb NEm and 62.6 Mcal/lb NEg. Bunks were managed according to a slick bunk management system. Fecal samples were collected from a subsample of steers from each pen (n = 5 steers/pen) on study days 1, 28, 56, 112, and 140 via rectal palpation and composited by pen for the determination of Salmonella prevalence using selective enrichment and culture media. Following evisceration and hide removal during harvest, subiliac lymph nodes were obtained from an equal number of steers from each treatment (collected from every other steer during the harvest procedure). Data were analyzed as a randomized complete block design with pen as the experimental unit; an a level of 0.05 determined significance. Live-basis final BW and average daily gain tended (P = 0.06) to be reduced for CLO. No differences were detected (P = 0.11) between treatments for dry matter intake or gain efficiency. Treatment did not affect dietary NE utilization efficiency or calculated dietary NE content based upon observed performance (P = 0.46). No differences were detected between treatments for any carcass traits (P = 0.15). No Salmonella was recovered in any fecal samples collected on study days 1, 28, or 56. On day 112, steers from CLO had a numerically lower (P = 0.17; 25.0 vs. 8.3%) incidence of fecal Salmonella compared to CON. On study day 140, fecal Salmonella incidence did not differ between treatments (P = 0.34; 0.0 vs. 8.3%) for CON and CLO, respectively. Collectively, these data suggest that B. subtilis PB6 did not influence feedlot phase growth performance or fecal Salmonella prevalence. Additionally, Salmonella was not observed in the subiliac lymph nodes of any steers upon harvest.