Production Response of Dairy Cows Fed Soybean Meal Heat Treated with Different Methodologies

Abstract

This study evaluated the production response of dairy cows fed soybean meal (SBM) ruminally protected by three different methods. Treatments were a control diet containing solvent-extracted SBM (SESBM) and three diets in which part of the SESBM was replaced either by expeller SBM (ESBM; SoyPlus®; West Central Soy, Ralston, IA), SESBM nonenzymatically browned with xylose (SESBM + X; SoyPass®; LignoTech, Overland Park, KS), or SESBM cooked with soybean hulls and water (SESBM + SHW; AminoPlus®; AG Processing Inc., Omaha, NE). Sixteen Holstein cows were utilized in a 4 × 4 Latin square design with 21-d periods. Diets were formulated to be isonitrogenous (CP = 17.5% of DM), isoenergetic, and to have similar NDF and fatty acid concentrations. The SESBM diet was deficient in ruminally undegraded protein (RUP), but the other three diets were designed to have adequate and equal RUP levels. Contrasts tested RUP level (SESBM vs ESBM, SESBM+ X, and SESBM + SHW), expeller vs cooking (ESBM vs SESBM + X and SESBM + SHW), and the effect of different procedures within cooking (SESBM +X vs SESBM + SHW). There were no significant effects on DMI or milk production when feeding SBM vs ruminally protected SBM. Feeding protected SBM decreased protein percentage, but not protein yield. Revenue ($/d per cow) was calculated for each cow within treatment using $2.62/kg of milk fat and $4.33/kg of milk protein. Ninety percent confidence intervals (least squares means for revenue ± 1.64 × SED [standard error of the difference]) were 8.29 ± 0.30 for SESBM, 8.31 ± 0.30 for SESBM, 8.31 ± 0.30 for SESEBM + X, and 8.55 ± 0.30 for SESBM + SHW. These data do not support indiscriminate use of protected SBM.