In-Vitro Starch and NDF Digestibility Using Rumen Fluid from Control and Bovamine® Supplemented Cows

Probiotics are commonly fed to dairy cattle to improve feed efficiency and increase milk yield. The objective of this study was to determine the effects of a probiotic, (Bovamine®; Nutrition Physiology Company, LLC. Guymon, OK) consisting of Lactobacillus acidophilus (LA) and Propionibacterium freudenreichii (PF), on the in vitro digestibility of starch and neutral detergent fiber (NDF). Starch and NDF are the primary carbohydrate sources in dairy cattle diets from which they receive energy. There have been mixed results in performance when cows were fed the PF plus LA probiotic in beef and dairy cattle. The hypothesis of this experiment was that the probiotic would increase in-vitro starch and NDF digestibilities. Four rumen-cannulated, primiparous Jersey cows were used in a 2x2 crossover design experiment. Two cows were fed the LA and PF probiotic as a top dress and two were fed a control (ground corn) top dress. Rumen fluid from the two cows in each treatment group was pooled, creating two sources of ruminal fluid. The fluid was filtered and combined with a buffer before being inoculated into tubes containing no feed, ground corn, or ground alfalfa. Tubes were incubated for 0, 2, 4, 8, 12, 36, or 48 hours in a 39° C water bath with corn and 0, 2, 4, 8, 12, 36, 48, or 96 hours with alfalfa hay. Dry matter disappearance was used to represent starch digestibility since corn is 75% starch. After incubation, the samples were dried and analyzed. There were no significant changes in dry matter disappearance for corn or alfalfa. There was also no difference in digestibility rate or ruminal degradation in corn or alfalfa dry matter. There was a significant decrease in ruminal degradation of NDF in the Bovamine® supplemented group; however, this result would need to be confirmed with further study. From this study, it can be concluded that further research would be needed to determine if Bovamine® has any effect in the rumen or if the effect is primarily in the hindgut.