Soybean Meal Use in Dairy Rations
The effects of protein source on milk yield, milk composition and blood amino acids were determined in research reported from South Dakota State University. Twelve Holstein cows were fed different levels of soybean meal and fish meal in a 4x4 Latin square design experiment with each diet fed for a 21-day period. The basal diet was 25% corn silage, 25% alfalfa hay and 50% concentrate. Fish meal replaced soybean meal on an isonitrogenous basis at 0, 25, 50 and 100% replacement. Dry matter intake and milk yield were not affected by treatment. Milk composition changes were non-significant with protein trending higher and milk fat trending lower as fish meal replaced the soybean meal in the basal diet. The researchers measured the extraction of various amino acids from the blood by the mammary gland and found methionine, lysine and phenylalanine to be the most limiting amino acids. Replacing some of the soybean meal in the diet with fish meal may improve the protein content of the milk but did not have a positive impact on milk fat or milk yield. This experiment indicates that the nutritionist has a lot of flexibility in selecting ingredients for dairy rations. The ingredient’s price, availability and composition are three major determinants of use level, provided the ingredients do not change the quality characteristics of the milk.
AbuGhazaleh, A.A., D.J. Schingoethe and A.R. Hippen. 2001. Blood amino acids and milk composition from cows fed soybean meal, fish meal, or both. J. Dairy Sci. 84(5):1174-1181.
