Relation of amount and quality of protein in the diet to free gossypol tolerance by the rat

Authors:
  • IEI. P. Earle
    I. P. Earle
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Abstract
Summary and Conclusions: The rat‐repletion method for protein assay has been used to estimate effects on tolerance for free gossypol of a) difference in source or kind of protein; b) level of total nitrogen or protein intake; and c) changes in amino acid content or balance in the nitrogen allowance. The data demonstrate that the first two of these factors at least influence the depression in weight repletion of these protein depleted rats which may be brought about by an intake of free gossypol. It has been shown that a daily intake of 9.5 mg. of free gossypol, when total daily protein intake is limited to 160 mg. of nitrogen, is a borderline level which depresses weight gain when the protein is supplied by some meal mixtures but is without effect with some others.It has further been demonstrated that the toxic or weight‐depressing effect of 9.5 mg. of free gossypol which has been obtained with a nitrogen intake of 160 mg. may be nullified by increasing the protein intake 50% or more. Attempts to render ineffective an intake of 9.5 mg. gossypol at the lower nitrogen level by replacing a part of the nitrogen allowance with different amounts of some amino acid or amino acid combinations have not been markedly successful. The data do not identify the factor or factors in these protein supplements which influence gossypol toxicity. They do however point to the importance of considering both the amount and kind of dietary protein in attempts to establish a minimum level of free gossypol which is toxic for farm species, or a maximum level which will be tolerated.

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