Preweaning Megasphaera elsdenii supplementation in dairy-beef calves: Impact on performance, behavior, and rumen development

This study evaluated the effects of an oral probiotic capsule containing a live culture of Megasphaera elsdenii NCIMB 41125 on performance, feeding behavior, rumen pH and VFA concentration, and development of dairy-beef crossbred calves. Thirty-one male dairy-beef crossbred calves (Holstein × Angus; mean ± SD; 45.3 ± 7.1 kg; 8.2 ± 2.0 d old) were enrolled in a blinded, 76-d randomized trial. Calves were randomly assigned to one of 3 treatments: placebo, probiotic capsule administration on d 15, or probiotic capsule on d 15 plus a second capsule on d 39 of the study. Calves were housed individually with ad libitum access to water and calf starter and were fed 7 L/d of milk replacer (1,050 g of powder/d) in 2 meals until d 41, then 3.5 L/d in 2 meals until weaning on d 56. Behavioral observations were recorded in 1-min intervals using a wall-mounted camera. Rumen fluid samples were collected on d 14, 35, 49, 58, and 70, and analyzed for pH and VFA. Upon euthanasia on d 77, forestomach weights were recorded and rumen papillae dimensions were measured. Mixed linear models were used for statistical analysis. Probiotic treatment resulted in greater daily solid feed DMI and ADG, particularly during weaning and postweaning periods. Additionally, probiotic-treated calves spent more time drinking water and tended to have lower rumen pH compared with control calves. Empty rumen weight and papillae area were greater in calves supplemented with the probiotic capsule on d 15 compared with the other treatments. These findings suggest that preweaning M. elsdenii supplementation enhances performance and rumen development in dairy-beef crossbred calves. However, the effects of timing and number of capsule applications on rumen development and calf performance should be further investigated. Further research should also investigate the probiotic's effect on the rumen microbiome and fermentation dynamics throughout the rearing period using detailed microbiome analysis.