Supplementing yeast culture (Saccharomyces cerevisiae) for late lactating dairy cows fed diets varying in starch content

Thirty-six lactating Holstein cows averaging 258 days in milk were used to study the supplementation of yeast culture (Levucell SC20 - Lallemand) in dairy diets with two starch contents (22 vs. 32%). The lowest starch content was obtained by partial (50:50) replacement of finely ground corn by dried citrus pulp. A replicated 4 x 4 Latin square design was used with four periods of 24 days each. The first 20 days were used for diet adaptation and the last four for data collection. The following variables were evaluated: dry matter intake, milk yield and composition, and plasma glucose and urea nitrogen. Yields of milk, fat corrected milk, protein, lactose, and total solids as well as concentration of plasma glucose were not affected by treatments. Milk fat content tended to increase by feeding yeast culture and high starch diets while milk fat yield tended to be highest only when yeast Culture was fed together with the high starch diet. Partially replacing corn with dried citrus pulp reduced both milk urea nitrogen and plasma urea nitrogen in the present trial.