56. The Nutritive Value of Proteins for Milk Production. I. A Comparison of the Proteins of Beans, Linseed, and Meat Meal

Abstract

The protein requirements for maintenance and milk production are based on the well-known investigations of Kellner, Armsby, Haecker, Savage and others, who recommend feeding standards varying from 0·5 to 0·;8 lb. digestible crude protein per 1000 lb. live weight for maintenance, and from 0·52 to 0·63 lb. digestible crude protein per 10 lb. milk for milk production. A detailed study of the work of these investigations shows that in many instances nitrogen equilibrium has been obtained on considerably lower planes of protein intake: but the figures have been arbitrarily raised, partly to provide a sufficient safeguard against underfeeding, and partly on the assumption that the excess food protein could exert a stimulating effect on mammary secretion. Recent investigations, particularly those of Hills and his associates (l), Perkins (2), Buschmann(3) and Savage and Harrison (4) indicate that the existing protein standards could, in fact, be considerably reduced. The above investigations have, however, been limited to a study of the quantity of protein required for maintenance and milk production, and no account has been taken of the possible effect of variations in the quality of proteins on their utilisation.