Effect of yeast cultures on performance of lactating dairy cows: a field study

Three hundred six lactating Holstein cows in the first 120 d of lactation from seven farms in Pennsylvania were used to evaluate supplementation of two Saccharomyces cerevisiae yeast cultures containing about 10(8) cfu/g viable yeast cells on milk production and composition. Cows were fed individually and grouped into three blocks based on lactation numbers 1, 2, and 3 or greater, and, within block, randomly assigned to one of three treatments for a 14-wk study. The three treatments were 1) control, 2) yeast culture fermented on ground cornmeal and corn gluten meal (5.3 x 10(10) cfu/d per cow), and 3) yeast culture fermented on cornmeal and soybean meal (5.1 x 10(10) cfu/d per cow). The three treatments were mixed with cornmeal and 114 g per cow was fed daily as a top-dressing. Milk production, milk fat and protein percentage, milk fat and protein production, and 3.5% FCM were not affected by either yeast treatment. There were no significant interactions of farm by treatment, lactation number by treatment, or week by treatment. No differences in performance were significant for early lactation cows that calved during the trial, but FCM tended to be higher for treatment than for the control cows. Daily DMI measured on 39 cows at one location did not differ among treatments. Yeast supplementation was not beneficial for any production parameters under the nutritional management programs of these seven dairy farms.