Isoleucine Need of Swine at Two Stages of Development

Abstract

Four experiments were conducted to determine the isoleucine need of swine at two stages of development, namely, the baby pig weighing about 5 kg. and the finishing pig at 45 kg. liveweight. Soluble blood flour plus methionine was used as the sole or primary source of protein in the diets fed. With a semi-synthetic diet containing 22% protein and 3278 metabolizable calories per kilogram, the baby pig exhibited the maximum rate and efficiency of gain at an L-isoleucine level of 0.76% of the diet, which is equal to 3.45% of the dietary protein. In a similar diet containing 13.4% protein and 3330 metabolizable calories per kilogram, the finishing pig required a level of L-isoleucine equal to 0.35% of the diet or 2.63% of the dietary protein. A diet containing yellow corn andsoluble blood flour, 22.4% protein, and 3276 metabolizable calories per kilogram was fed. In such a diet, the baby pig required isoleucineat 0.70% of the diet or 3.17% of the dietary protein, but the finishing pig failed to respond to isoleucine additions. Thus, on such a diet the isoleucine need of the finishing pig is not more than about 0.47% of the diet or 2.10% of the protein. Copyright © 1963. American Society of Animal Science . Copyright 1963 by American Society of Animal Science