Effect of Heating Soybean Meal for Dairy Cows

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Abstract
Effects of different amounts of heating in processing of soybean meal were evaluated in terms of in vitro digestibility of dry matter and protein in the meal and its feeding value for dairy cows. Varying the temperature during 1 stage of processing produced soybean meals having protein dispersibility indexes of 51.4, 41.8, 30.2, 18.0 and 8.2. In vitro microbial digestibility and dry matter and protein in the meals was related inversely to temperature during processing. Enzymatic digestion during a 2nd stage of the in vitro procedure increased in soybean meals heated more extensively during processing so that total disappearance of dry matter and protein was reduced only a small amount. In a feeding trial with 22 lactating cows, the more extensively heated soybean meal was compared with meal processed in a conventional manner at 2 protein intakes. Protein of soybean meal was 59 and 32% of total protein intake by cows in the 2 groups. Milk yield of cows fed extensively heated soybean meal was higher than that of cows fed regular soybean meal. Milk composition was not changed.