Extruded Soybean Meal Increases Feed Intake and Milk Production in Dairy Cows

Abstract Text: Extruded soybean meal (ESBM) has higher fat content and lower ruminal protein degradability than solvent-extracted soybean meal (SSBM), but information on its nutritive value for dairy cows is limited. A replicated 3 × 3 Latin square design trial with 9 Holstein cows (parity, 3.1 lactations; DIM and BW at the beginning of the trial, 161 ± 21 d and 637 ± 20.3 kg, respectively) and 28-d experimental periods was conducted to evaluate the effect of ESBM processed at 2 extruder temperatures, 149°C (LTM) and 171°C (HTM), on milk production and composition and blood plasma amino acid profile in dairy cows. The control diet contained 13% SSBM [53.8% crude protein (CP) with 71.4% ruminal degradability and 1.8% ether extract (EE)], which was replaced with equivalent amount (DM basis) of LTM (46.8% CP, 59.8% degradability, 10.0% EE) or HTM (46.9% CP, 41.1% degradability, 10.9% EE) ESBM in the 2 experimental diets (LTM and HTM, respectively). Other ingredients in the diets were (DM basis): 40% corn silage, 20% alfalfa haylage, 5% grass hay, 9% ground corn grain, 5% cottonseed hulls, 5% molasses, salt, urea (LTM and HTM diets only), and mineral-vitamin premix. The diets had 16% CP and met or exceeded the NE_L and metabolizable protein requirements of the cows (NRC, 2001). Both LTM and HTM tended to increase (P = 0.06) DMI compared with the control diet (28.3, 28.2, and 26.8 kg/d, respectively). This resulted in increased (P < 0.001) milk yield for both ESBM diets: 40.2 and 40.8 vs. 37.5 kg/d, respectively. Milk fat (3.38 to 3.60%) and milk true protein (2.86 to 2.95%) contents and milk fat yield were not affected by treatment. Milk protein yield tended to be increased (on average by 60 g/d; P = 0.09) by the ESBM diets. Plasma urea N and MUN were increased (P < 0.03) 18 and 13%, respectively, by the ESBM diets compared with the control. Blood plasma concentrations of His, Leu, and Val were increased (P ≤ 0.03) by HTM compared with the control and LTM. Concentration of plasma Met was decreased (P = 0.05) and that of carnosine was increased (P= 0.02) by the ESBM diets compared with the control. This study demonstrated that replacement of SSBM with ESBM in the diet of lactating dairy cows increased feed intake, which resulted in increased milk yield, and increased milk protein yield.

Keywords: solvent-extracted soybean meal, extruded soybean meal, dairy cow