Amino Acid Imbalance: Rations Low in Tryptophan, Methionine or Lysine and the Efficiency of Utilization of Nitrogen in Imbalanced Rations

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Abstract
Three experiments were conducted with growing chickens. In the first and second of these, an amino acid imbalance (deficiency) was created with rations low in tryptophan or methionine. In the third experiment diets containing three levels of energy were formulated in such a manner that birds consumed equal quantities of food and therefore of protein and of the most limiting amino acid (lysine) when fed rations that were either imbalanced or balanced. This permitted a comparison of the efficiency of utilization of the protein and of the most limiting amino acid. No impairment in utilization occurred in terms of either body weight gain or carcass nitrogen content of birds fed imbalanced versus normal rations. The results indicate that the term imbalance as used in its present context cannot be differentiated from an amino acid deficiency.
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