211 Evaluation of CLOSTAT-500® on growth performance and fecal Salmonella prevalence in yearling beef steers during the feedlot receiving phase

Abstract

Abstract Two-hundred and thirty eight crossbred beef steers (initial BW = 419 ± 32.4 kg) were used to evaluate the influence of a patented probiotic on growth performance responses and fecal Salmonella prevalence during a 28-d feedlot receiving period at the South East Research Farm (SERF) feedlot located near Beresford, SD. Steers were allotted to 24 pens (9 to 10 steers/pen) and assigned to one of two treatments (12 pens/treatment): no probiotic (CON) or 0.5 g·steer-1·d-1 of a Bacillus subtilis PB6 probiotic (CLOSTAT-500®, Kemin Industries, Des Moines, IA; CLO). Steers were transitioned from a 70% concentrate diet (DM basis) to a 92% concentrate diet (DM basis) over a 14-d period. The final diet contained (DM basis): 12.5% CP, 2.08 Mcal/kg of NEm, 1.40 Mcal/kg of NEg, 30 g/907-kg of monensin sodium, and 0.45 mg/kg of chromium propionate (KemTRACE® Chromium, Kemin Industries, Des Moines, IA). Fecal samples were collected on study d 1 and 28 (6 and 34 d following arrival to the SERF, respectively) from sentinel steers (n = 5/pen) via rectal palpation and composited by pen for determination of Salmonella prevalence using selective enrichment and culture medias. Steers were fed once daily and bunks were managed according to a slick bunk management approach. Data were analyzed as a randomized complete block design; pen served as the experimental unit and an α of 0.05 determined significance. No differences were detected (P ≥ 0.25) between treatments for ADG, DMI, or gain efficiency during the initial 28-d feedlot receiving phase. Additionally, no Salmonella was recovered in any fecal samples collected. These data indicate that Bacillus subtilis PB6 had no influence on receiving phase growth performance, and fecal Salmonella prevalence was not observed in yearling steers placed on feed in March in southeastern South Dakota.