Bacillus subtilis PB6 supplementation in weaned Holstein steers during an experimental Salmonella challenge

Authors: Broadway, Paul; Carroll, Jeffery - Jeff Carroll; Sanchez, Nicole; CALLAWAY, TODD - University Of Georgia; LAWHON, SARA - Texas A&M University; GART, ELENA - Texas A&M University; BRYAN, LAURA - Texas A&M University; Nisbet, David; HUGHES, HEATHER - Sciwrite Consulting, Llc; LEGAKO, JERRAD - Texas Tech University; HERGENREDER, JERILYN - Kemin Industries, Inc; ROUNDS, WHITNEY - Kemin Industries, Inc

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2020
Publication Date: 4/28/2020
Citation: Broadway, P.R., Carroll, J.A., Sanchez, N.C., Callaway, T.R., Lawhon, S.D., Gart, E.V., Bryan, L.K., Nisbet, D.J., Hughes, H.D., Legako, J.F., Hergenreder, J.E., Rounds, W. 2020. Bacillus subtilis PB6 supplementation in weaned Holstein steers during an experimental Salmonella challenge. Foodborne Pathogens and Disease. 17:8. https://doi.org/10.1089/fpd.2019.2757.
DOI: https://doi.org/10.1089/fpd.2019.2757

Interpretive Summary: Salmonella is a bacterium that causes illness in humans and in livestock. Currently, prevention and treatment of this disease-causing bacterium in cattle is primarily accomplished using antibiotics. However, pressures currently exist to reduce or eliminate the use of antibiotics in food animals. Therefore, scientists from the USDA-ARS Livestock Issues Research Unit teamed up with scientists from Kemin Industries, Texas A&M University, Texas Tech University, University of Georgia, the USDA-ARS Feed and Food Safety Research Unit, and SciWrite Consulting to evaluate a commercially available probiotic as a potential alternative to antibiotics in treating young calves with Salmonella. Results from this study revealed that the calves fed the probiotic had significantly less Salmonella than the calves that did not receive the probiotic. Additionally, body temperature was greatly reduced in calves receiving the probiotic. This study demonstrates that this particular probiotic was effective in reducing Salmonella in young calves and reducing some of the illness responses to infection. This information is important as cattle farmers look for effective antibiotic alternatives to improve calf health and productivity. This information will also be of particular interest to food producers and consumers because reducing the amount of Salmonella in the animal decreases the likelihood of food contamination and human illness.

Technical Abstract: To evaluate the effects of a patented Bacillus subtillus probiotic, weaned Holstein steers, not shedding Salmonella, (n=40; ~90 kg) were supplemented (CLO) or not (CON) with CLOSTAT® (13 g/hd/d; Kemin Industries, Des Moines, IA) in a starter ration for 35 d. The calves were assigned to 1 of 4 treatments in a 2 x 2 factorial design with CLO and CON calves that were orally administered Salmonella (STM) or not (NoSTM). Calves were challenged with 1.6 x 106 CFU Salmonella Typhimurium (resistant to 50 µg/ml nalidixic acid) in 1 L of milk replacer on d 0. Blood samples were collected via jugular catheters every 6 h for 96 h, and body temperature was collected every 5 min via indwelling rectal temperature recording devices. Five calves from each treatment were harvested 48 h post-challenge, and the remaining calves were harvested 96 h post-challenge. During necropsy, tissues were collected for the isolation and quantification of the inoculated STM from various tissues. The CLOSTM group had reduced STM concentrations in the jejunum, ileum, and transverse colon 48 h after the challenge (P=0.03), but were not different 96 h post-challenge (P>0.05). Decreased (P<0.01) rectal temperatures were observed after the challenge in CLOSTM calves when compared to CONSTM calves. White blood cells and lymphocytes were increased (P=0.05) in CLOSTM calves after the challenge in comparison to other treatments. In calves given STM, the CLO group had greater feed disappearance before and after the challenge (P<0.01) compared to the CON group. Increased serum IL-6 and IFN-' concentrations were observed in the CONSTM group compared to other treatments. Overall, CLO reduced Salmonella presence and concentrations in gastrointestinal tissues while simultaneously reducing the severity of the salmonellosis as indicated by blood parameters and the reduced febrile response.