The effects of supplementing Bacillus subtilis PB6 on health outcomes, Salmonella spp. prevalence, growth performance, and carcass characteristics in finishing beef cattle.

Authors: HANRATTY, ASHLEE - Texas Tech University; HALES, KRISTIN - Texas Tech University; DORNBACH, COLTEN - Texas Tech University; Sanchez, Nicole; WORD, ALYSSA - Cactus Research; HOLLAND, BEN - Cactus Research; MAXWELL, CASEY - Cactus Research; HERGENREDER, JERILYN - Kemin Industries, Inc; CANTERBURY, LANDON - Kemin Industries, Inc; LEONHARD, J - Kemin Industries, Inc; VASCONCELOS, J - Kemin Industries, Inc; LAFLEUR, J - Kemin Industries, Inc; TROJAN, SARA - Peak Beef Nutrition And Management Consulting, Llc; Broadway, Paul

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Salmonella is one of the most common foodborne illnesses in the U.S. and poses a public health risk. Salmonella is a threat to all segments of food animal production because of the impact on livestock and consumers of animal products. Feedlot cattle are vulnerable to several different foodborne pathogens, including Salmonella. Previous studies found feeding cattle a probiotic decreased Salmonella in the small intestine. A study was conducted by ARS scientists and university and industry partners to evaluate feeding cattle a probiotic on the health, growth performance, and Salmonella prevalence in feedlot cattle. Results found feeding cattle the probiotic for the first 60 days and for the entire feeding period had no effect on Salmonella in feces or peripheral lymph nodes. These data will be of interest to scientists in the field of animal health as well as beef producers.

Technical Abstract: The objectives of this study were to evaluate the effects of supplementation with B. subtilis PB6 on health outcomes, growth performance, fecal Salmonella prevalence, and carcass characteristics in finishing beef steers supplemented either the first 60 days or the entire feeding period with B. subtilis PB6. Crossbred beef steers (n = 3,150; arrival BW 287 ± 30.6 kg) were used in a randomized complete block design consisting of 3 dietary treatments (n = 15 blocks/treatment). Treatments included: 1) control diet, contained no Bacillus subtilis PB6 (CON); 2) diet included Bacillus subtilis PB6 (CLOSTAT 500) at 0.5 g/steer daily to provide 6.6 × 109 CFU/g of active ingredient for the duration of the feeding period (CLO); 3) diet included Bacillus subtilis PB6 at 0.5 g/steer daily during the initial 60 days of the feeding period (CLO60). Metaphylaxis was administered after arrival (n = 7 blocks/21 pens received metaphylaxis) to prevent bovine respiratory disease. Fresh fecal matter was collected aseptically from multiple locations (n = 10), and lymph nodes were obtained from a subset of carcasses within each lot (n = 12) at harvest to determine Salmonella prevalence. No interactions were observed between treatment and metaphylaxis throughout the study (P > 0.25). The percentage of respiratory deaths were greatest for steers in CLO60 than CLO and CON (P = 0.03) from d 0 to d 60. There were no growth performance differences noted among treatment throughout the study (P > 0.33). There were no differences noted in lymph node prevalence of Salmonella among treatments (P = 0.98). There was a decrease in fecal prevalence in CON vs. CLO and CLO60 from d 45 to 90 (P = 0.05). The supplementation of Bacillus subtilis PB6 for the first 60 days of the feeding period and for the entire feeding period had no effect on the prevalence of Salmonella in the feces or subiliac lymph nodes.