RESPONSE OF PIGLETS TO SUBOPTIMAL PROTEIN DIETS SUPPLEMENTED WITH LYSINE, METHIONINE, THREONINE AND TRYPTOPHAN

Abstract

A 4-wk feeding trial was conducted with castrated piglets weaned between 18 and 21 d of age, and fed either 22, 29 or 17% crude protein isocaloric diets, adjusted to the same calculated content for total lysine, methionine, threonine and tryptophan. Piglets fed the 22 or 19% protein diets had the same feed intake, practically the same growth rate, and the same gain/feed ratio. Those fed the 17% protein diet had the same feed intake, but gained less than those fed the 19% protein diet. Therefore, it seems possible to lower the protein content of a weanling diet from 22 to 19%, provided that lysine, methionine, threonine, and tryptophan are adjusted to the same calculated content. Key words: Piglets, lysine, methionine, threonine, tryptophan