Brewer's Yeast Slurry. II. A Source of Supplementary Protein for Lactating Dairy Cattle

Brewer's yeast slurry and soybean meal each were incorporated in complete rations at 6 and 12% of dry matter to increase crude protein from 13% (negative control) to 15 and 17%. Thirty Holstein cows were blocked on age, stage of lactation (average 200 days), and milk yield (average 19.4 kg) and assigned to treatments within blocks. Data analysis was on differences between the 28-day treatment and average of preceding and subsequent control periods when the 15% protein soy diet was fed.