Effects of direct-fed microbials on weight gain and gastrointestinal bacteria microbiome composition in weaned heifers

Abstract

Weight gain and fecal analysis on 179 heifer from two breeds of cattle, Angus and Salers, were analyzed after being treated with a direct fed microbial (DFM) supplement. Heifers were split into one of three treatment groups with the control being drenched with water, a second group being drenched with 1/2oz of the DFM, and a third group being drenched with 1oz of the DFM. Heifers were monitored over a four week period and drenched on day 0 and day 28 to measure changes in weight gain and microbiome composition. Fecal samples were taken rectally from the fecal group (FG) weekly during the duration of the trial. Overall, the final model ANOVA resulted in a p-value of .9689, concluding no significant difference between the 3 treatment levels for weight gain. Time proved to be the predominant driver of gastro-intestinal microbial composition and probiotic supplementation did not lead to significant changes to the microbiome community structure. Chao1 and ACE models ran on fecal samples indicate significant impact of probiotic treatment on microbial richness and indicate that supplementation leads to greater diversity and, in turn, may mean a more robust microbiome.