Limiting amino acids in Colombian floury-2 corn for growth of young rats.

T HE inferiority of Colombian floury-2 corn to Colombian opaque-2 corn as the only energy-protein source for growing rats and swine has been reported (Maner et al., 1971). Cromwell et al. (1968) showed that floury-2 corn is superior to opaque-2 corn for growth of chicks because of the methionine deficiency of opaque-2 corn relative to the chick's methionine requirement. The pig and rat have lower sulfur amino acid requirements than the chick and, therefore, would not be expected to respond to methionine supplementation of floury-2 or opaque-2 corn. Oestemer et al. (1970) and Gallo, Maner and Jimenez (1970a) found no response to methionine supplementation of opaque-2 and Colombian opaque-2 corns for pigs, respectively. The opaque-2 mutant gene was incorporated into indigenous Colombian corn at Insfituto Colombiano Agricultura (ICA) by Sarria and Cassalett (1969). Colombian opaque-2 corn has an excellent content of amino acids (Gallo, Maner and Corzo, 1969). Colombian floury-2 corn has been produced at ICA by the same procedure. However, the poor performance of rats and pigs fed Colombian floury-2 corn (Maner et al., 1971) suggests an inferior amino acid composition. The purpose of the present work was to determine the sequence of limiting amino acids in Colombian floury-2 corn using weight gain and efficiency of feed and protein utilization of the growing rat as the criteria of response.