Effects of a probiotic yeast in lactating ruminants: interaction with dietary nitrogen level

This study was designed to test the effects of a probiotic yeast (Saccharomyces cerevisiae I-1077) at two levels of nitrogen intake in early lactation, expressed as PDI (Protein truly Digestible in the small Intestine) at normal levels of 108 g PDI kg−1 DM (dry matter) vs. low levels of 78 g PDI kg−1 DM, on dry matter intake, milk production and composition and on blood parameters. Twenty-eight dairy goats received a complete diet including alfalfa hay (25% of dry matter), pressed sugar beet pulp silage (50%) and a compound feed (25%). Supplying yeast decreased energy and nitrogen balances during the first 6 weeks after parturition. Yeast seemed to facilitate increased mobilization of body reserves and to increase milk fatty acid production. Thus, fat-corrected milk yield increased during the period when animals are very susceptible to nutritional stress.