Effect of yeast culture (Saccharomyces cerevisiae) on adaptation of cows to diets postpartum.

For approximately 14 d prepartum and exactly 14 d postpartum, 20 multiparous Holstein cows were fed different basal diets that were supplemented, or not supplemented, with a yeast culture preparation. Cows supplemented with yeast culture lost less body condition prepartum, which was consistent with numerically higher body weight gain. No treatment differences were found in prepartum or postpartum dry matter intakes (DMI) or components of DMI. In addition, the extent of the depression in DMI prepartum and the rate of increase in DMI postpartum were not influenced by yeast culture supplementation. Milk and milk component yields were not influenced by yeast culture supplementation. Cows in both groups had higher calculated net energy for lactation for the diets postpartum than would have been expected based on values of the National Research Council for feedstuffs. The increased net energy for lactation seemed to be related to higher than expected metabolic efficiency during early lactation. Results of both the prepartum and postpartum periods were consistent with the hypothesis that supplementation of yeast culture in the diet increased net digestion in the forestomach, particularly of fiber, leading to increased energy output. However, there was no evidence to suggest that supplementation of yeast culture prepartum alleviated the reduction in DMI prepartum or improved the rate of increase in DMI postpartum.