LAUSR

Stress in pre-ruminant calves can impact the functionality of the gastric epithelial lining, thereby impacting calf health during times of stress and potentially later in life. To mitigate this challenge, milk replacers frequently contain antibiotics to reduce the proliferation of harmful bacteria that may result in disease in pre-ruminant, milk supplemented calves. However, there is consumer and regulatory pressure to reduce the reliance on these antimicrobials and evaluate alternatives, such as probiotics, that may shift gut bacterial populations without impacting potential antimicrobial resistance. The objective of this study was to determine if supplementing calves with Lactobacillus and Bacillus species in milk replacer impacts pre-ruminant calf health. The project included 44 calves (50% Angus/50% Holstein) in a randomized complete block design, with calf serving as the experimental unit and age serving as a blocking factor. Calves were fed twice daily one of two treatments: 1) milk replacer with Lactobacillus and two Bacillus species at a total rate of 1.25 x 10^9 cfu/head/day; or 2) non-treated milk replacer. There were 22 replicates per treatment. To determine health status, calves were scored daily based on health indicators for fecal consistency or eye, nose, or ear normality. Health scores were ranked from 0 to 3, with 0 representing normal and 3 signaling severe symptoms, such as bilateral eye or nasal discharge, ear droop, or watery feces. Statistical analysis was performed using the GLIMMIX procedure of SAS. Overall, there was no evidence (P > 0.05) that Lactobacillus and Bacillus inclusion impacted any measured health parameter. Notably, approximately 50% of calves had fecal scores indicating some level of watery stool, but this was not impacted (P > 0.05) by probiotics. In summary, the inclusion of probiotics in calf milk replacer did not appear to impact calf health in the first 30 days.