Further studies on the amino acid deficiencies of plant proteins

Abstract

By means of paired feeding tests, it has been shown that sesamemeal is deficient in cystine and that cottonseedmeal is not deficient in this amino acid. Bran and coprameal are apparently not deficient in lysine, while the supplementation of peanutmeal with methionine did not enhance its growth-promoting properties. Tryptophane does not appear to be a secondary amino acid deficiency in either soyabeans or linseed meal. By means of nitrogen balance studies, it was shown that the increased weights obtained by the supplementation of sesamemeal with cystine are due to a better utilization of the sesamemeal nitrogen. The unsupplemented biological value previously determined by Smuts and Malan was 71 and the supplemented biological value as determined in this paper 80. In the case of cottonseed supplemented by cystine, the biological value of 84 is only slightly higher than 81, and does not signify a significantly better utilization of nitrogen of the supplemented over the unsupplemented cottonseedmeal.