A note on the effect of dietary protein concentration, sex, type and live weight on whole-body amino acid composition of the growing pig

Abstract

Seventy-two Landrace pigs were used to study the effects of dietary crude protein concentration (197, 168 and 137 g/kg air dry meal), sex, type and live weight on the whole- body (gut content included) amino acid composition of growing pigs. Boars and gilts from two types (lean and obese) slaughtered at 20, 30 or 90 kg live weight were used. Mean whole-body amino acid concentrations were: lysine 63·4; methionine 21·8; cystine 15·8; threonine 35·1; leucine 67·7; isoleucine 28·0; valine 40·5; phenylalanine 35·5; tyrosine 24·6 and histidine 26·8 g/kg protein. Dietary protein concentration had no effect on body amino acid composition. Boar values tended to be higher than those of gilts but there were no significant differences. Pigs of the obese type also tended to have higher values than lean pigs, with significant differences obtained for methionine, cystine, leucine, and isoleucine. Apart from cystine, live weight had no effect on whole-body amino acid composition, Cystine content however, decreased highly significantly from 17·1 g/kg protein at 30 kg live weight to 14·3 g at 90 kg live weight P (P < 0·001). When compared with the suggested ideal pattern for essential amino acids leucine and histidine values are higher and isoleucine slightly lower, with no conclusive indication on methionine and cystine.