Yeast culture supplementation effects on lactation performance, rumen fermentation characteristics, and abundance of major species of ruminal bacteria in mid-lactation Holstein dairy cows.

Document Type


Publication Date



American Dairy Science Association


Journal of Dairy Science




Suppl. 1






yeast culture, rumen bacteria, dry matter intake


Improvements in milk yield and efficiency have been observed when feeding yeast culture products to dairy cows, and this has been partially attributed to alterations in rumen fermentation. Therefore, this study aimed to evaluate the effects of feeding yeast culture [Cellerate Culture Classic HD (YC); Phibro Animal Health, Teaneck, NJ] on lactation performance, rumen fermentation characteristics, and rumen bacterial populations in lactating dairy cows. Forty mid-lactation Holstein dairy cows (121 ± 43 DIM; mean ± SD) were used in a randomized complete block design consisting of 7 d adaptation period and 60 d treatment period. Cows were blocked by parity, DIM, and previous lactation milk yield and assigned to a basal TMR plus 114 g/d of ground corn CON (n = 20) or basal TMR plus 100 g/d of ground corn and 14 g/d YC (n = 20). Blood and rumen fluid samples were collected at 0, 30, and 60 d. Rumen fluid was analyzed for ammonia-N, VFA concentrations, and relative abundance of bacterial populations via qPCR amplification. Data were analyzed using the MIXED procedure of SAS. Dry matter intake tended (P = 0.07) to be 1.4 kg/d lower in YC than CON cows, while milk yield was not affected (P = 0.43) by diet. Consequently, a trend (P = 0.07) was observed for greater milk efficiency in YC than CON cows (1.46 vs. 1.34 milk/ DMI). The trend (P = 0.11) for a Diet × Time interaction in rumen pH resulted in greater rumen pH in YC than CON cows at 60 d. Greater (P = 0.02) propionate was observed in YC than CON (26.9 vs 25.4%). A trend (P = 0.07) for lower acetate was observed in YC than CON (60.2 vs 61.2%). There was lower (P = 0.04) acetate:propionate ratio in YC than CON. Prevotella albensis, associated with improved feed efficiency, was greater (P = 0.05) in YC than CON. Ruminobacter amylophilus, related to rumen acidosis, had a Diet × Time effect (P < 0.01) with lower (P < 0.01) abundance in YC than CON at 30 d. These results suggest feeding YC may help maintain milk production during transient reductions in DMI, by modulating rumen microbiota and fermentation patterns.