Potential role of rumen bacteria in modulating milk production and composition of admixed dairy cows

Abstract

Cattle milk is an important food for the growing calf and humans because of its concentrated macro and micro nutrients. However, the quantity and quality of milk nutrients vary depending on several factors. This study evaluated the effect of dietary modification on rumen bacteria as well as the potential role of rumen bacteria in modifying milk production and composition profile. Using a 16S rRNA metagenomic approach, the study characterized the rumen bacterial community composition in four dairy cows and their milk production and composition. The results indicated that Bacteroidetes and Firmicutes were the dominant bacteria, totaling ∼83.7% of the rumen bacteria. An increase in concentrate proportion in diet led to an increase in the abundance of Bacteroidetes (P ≤ 0.05) and Proteobacteria while Firmicutes and Fibrobacter decreased. Milk production and composition were highly correlated with the abundance of various rumen bacterial members. Lentispaerae (P = 0.010), and Synergistetes (P = 0.011) exhibited a positive and significant correlation while Tenericutes (P = 0.009) showed a negative correlation with milk protein. Fusobacteria (P = 0.016) showed a negative correlation with milk lactose. Similarly, several genera showed correlations with milk parameters. The correlation between microbes with milk parameters implies that the bacterial community possesses the potential to influence milk production and composition.

Keywords: Cattle; diet; metagenomics; milk composition; milk production; rumen bacteria.