Effects of four soybean meal products on lactational performance of dairy cows

Thirty-two multiparous Holstein cows (152 days in milk, producing 90 lb/day of milk at the beginning of the study) were used in a 4 × 4 Latin square design with 28-day periods to investigate cow responsiveness to supplemental ruminally undegraded protein from 4 soybean meal products. The 4 products were: solvent soybean meal (SSBM), expeller soybean meal (ESBM), lignosulfonate-treated soybean meal (LSBM), and SSBM treated with 0.05% baker’s yeast and toasted at 212oF (YSBM). Diets were formulated by substituting all SSBM and part of ground corn with YSBM, ESBM, or LSBM to yield isonitrogenous diets. Diets were formulated to provide adequate ruminally degraded protein, but deficient ruminally undegraded protein and metabolizable protein supplies. No differences among dietary treatments were observed for dry matter intake, body weight gain, milk and component yields, or efficiency of milk production. Lack of response to changes in soybean meal source was likely because of adequate ruminally undegraded protein and metabolizable protein supply by all diets.