Short communication: Does early-life administration of a Megasphaera elsdenii probiotic affect long-term establishment of the organism in the rumen and alter rumen metabolism in the dairy calf?

Megasphaera elsdenii is a bacterial species of the rumen that can utilize lactate to produce butyrate, a key volatile fatty acid often implicated in driving calf rumen development. Because lactate is abundant in the rumen of young calves, administration of M. elsdenii to increase butyrate production and thus promote calf rumen development is an appealing possibility. The main objective of this study was to determine whether M. elsdenii administration to calves via oral drench at 14 d of age affected its long-term establishment at 70 d postadministration. Ruminal volatile fatty acid and lactate profiles and blood glucose and β-hydroxybutyrate concentrations were also examined to determine potential influence on rumen metabolism. Six neonatal Holstein heifer calves were blocked on d 1 by body weight (41.3 ± 1.8 kg) and total serum protein (5.23 ± 0.16 g/dL) and assigned to either the M. elsdenii (n = 3) or control (n = 3) treatment groups. On d 14, calves in the M. elsdenii group orally received 25 mL of a commercially available M. elsdenii suspension, whereas calves in the control group received 25 mL of the same product that had been autoclaved. Rumen contents and blood samples were collected weekly from each animal until 84 d of age. The oral administration of M. elsdenii at 14 d did not increase the abundance of M. elsdenii 70 d postdosing, alter rumen fermentation, or change blood metabolites associated with butyrate. These results suggest that a single administration of the M. elsdenii probiotic may not affect the rumen establishment of the organism.