Normal, Opaque-2, Waxy, Waxy Opaque-2, Sugary-2 and Sugary-2 Opaque-2 Corn (Zae Mays L.) Endosperm Types for Rats and Pigs. Studies on Protein Quality2

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Abstract
One metabolism and two growth trials involving 432 rats and one trial with 64 pigs were conducted to evaluate the protein quality of six near isogenic versions of the maize 3-way hybrid [(Oh43 × B37) × C103)] in protein-limiting diets. In 8% crude protein diets, rats fed opaque maize types (opaque-2, waxy opaque-2 and sugary-2 opaque-2) gained 143% faster and were 68% more efficient in converting feed to gain than rats fed non-opaque maize types (normal, waxy and sugary-2). These improvements were accompanied by a 5.5% lower dry matter digestibility, but a 10.5% improvement in biological value for opaque compared with non-opaque corns. Supplementation of the diets with lysine, tryptophan or both amino acids failed to eliminate the differences observed; diets containing opaque corns still supported higher rate of gain and improved feed efficiency as compared with those rats fed non-opaque corns. Pigs fed diets containing non-opaque corns supplemented with lysine and tryptophan showed 10.5% inferior feed efficiency, but 15% higher rate of gain than those fed opaque corns. In 11% crude protein diets, the differences observed in rat performance were smaller; at 14% protein, no differences were observed. It was found that higher contents of lysine and tryptophan in opaque maize are not the only reason for its superiority. Sugary-2 was found to be superior to normal corn; however its improvement was less than for opaque-2. These experiments indicated that the double mutants waxy opaque-2 znd sugary-2 opaque-2 are similar to opaque-2 in protein quality. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.