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 lactat ion from seven farms in Pennsylvania were used to evaluate supplementa tion of two Saccharomyces cerevisiae yeast cultures containing about 1 0(8) cfu/g viable yeast cells on milk production and composition. Cows were fed individually and grouped into three blocks based on lactatio n 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 we re 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 ferment ed on cornmeal and soybean meal (5.1 x 10(10) cfu/d per cow). The thre e treatments were mixed with cornmeal and 114 g per cow was fed daily as a top-dressing. Milk production, milk fat and protein percentage, m ilk fat and protein production, and 3.5% FCM were not affected by eith er yeast treatment. There were no significant interactions of farm by treatment, stage of lactation by treatment, lactation number by treatm ent, or week by treatment. No differences in performance were signific ant for early lactation cows that calved during the trial, but FCM ten ded to be higher for treatment than for the control cows. Daily DMI me asured on 39 cows at one location did not differ among treatments. Yea st supplementation was not beneficial for any production parameters un der the nutritional management programs of these seven dairy farms.