The objective of this study was to assess the effects of 2 extruded soybean meals (ESBM) processed at 2 extruder temperatures, 149°C (LTM) and 171°C (HTM), on performance, nutrient digestibility, milk fatty acid and plasma amino acid profiles, and rumen fermentation in lactating dairy cows. Nine multiparous Holstein cows were included in a replicated 3. ×. 3 Latin square design experiment with three 28-d periods. The control diet contained 13% solvent-extracted soybean meal (SSBM; 53.5% crude protein with 74.1% ruminal degradability and 1.8% fat), which was replaced with equivalent amount (dry matter basis) of LTM (46.8%, 59.8%, and 10.0%) or HTM (46.9%, 41.1%, and 10.9%, respectively) ESBM in the 2 experimental diets (LTM and HTM, respectively). The diets met or exceeded the nutrient requirements of the cows for net energy of lactation and metabolizable protein. The 2 ESBM diets increased dry matter intake and milk yield compared with SSBM. Feed efficiency and milk composition were not affected by treatment. Milk protein yield tended to be increased by ESBM compared with SSBM. Milk urea N and urinary urea N excretions were increased by the ESBM diets compared with SSBM. Concentration of fatty acids with chain length of up to C17 and total saturated fatty acids in milk fat were generally decreased and that of C18 and total mono- and polyunsaturated fatty acids was increased by the ESBM diets compared with SSBM. Blood plasma concentrations of His, Leu, and Val were increased by HTM compared with LTM and SSBM. Plasma concentration of Met was decreased, whereas that of carnosine was increased by the ESBM diets. Treatments had no effect on rumen fermentation, but the proportion of Fibrobacter spp. in whole ruminal contents was increased by HTM compared with SSBM and LTM. Overall, data from this crossover experiment suggest that substituting SSBM with ESBM in the diet has a positive effect on feed intake and milk yield in dairy cows.
All Science Journal Classification (ASJC) codes
- Food Science
- Animal Science and Zoology