Effects of ruminal dosing of Holstein cows with Megasphaera elsdenii on milk fat production, ruminal chemistry, and bacterial strain persistence.

Megasphaera elsdenii is a lactate-utilizing bacterium whose ruminal abundance has been shown to be greatly elevated during milk fat depression (MFD). To further examine this association, a total of 23 cannulated multiparous Holstein cows were examined in 3 experiments in which strains of M. elsdenii were directly dosed into the rumen (~2 × 10(12) cells/dose); control cows were dosed with sterile lactate-free culture medium.