Isoleucine Need of Swine at Two Stages of Development

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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