The Essential Amino Acid (Except Tryptophan) Content of Colostrum and Milk of the Sow

Abstract

The essential amino acid composition (except tryptophan) of sows' colostrum and milk was determined and comparisons were made between these findings and the data on amino acid composition of cows' and ewes' milk reported in the literature. On the basis of total protein, sows' milk contained less of all amino acids studied, except histidine, than did cows' and ewes' milk. However, when amino acid composition is expressed in terms of milligrams per gram of milk, the milk of the sow was superior to that of the cow except in the case of methionine, and very similar to that of the ewe. Colostral protein was found to be higher in threonine, phenylalanine, valine and leucine, and lower in lysine and methionine than was milk protein. Histidine showed little variation throughout the lactation period. Isoleucine was found to be lower in the very first colostrum but quickly became constant in both later colostrum and milk samples. Arginine levels of the milk of the sows showed conflicting trends. Because sows' colostrum is high in leucine, valine and threonine, and because these three amino acids are known to constitute a large proportion of immune proteins, it is reasonable to assume that colostrum is high in antibodies. This emphasizes the value of colostrum in the nutrition of the very young pig.