Effect of Incremental Dosages of the Waxy Gene of Sorghum on Digestibility

Abstract
The effect of degree of the waxy characteristic of sorghum on in vitro and in situ digestibility was determined. Crosses were made within two pairs of sorghum cuftivars to produce grain with following genotypes: non-waxy (WxWxWx); intermediate waxy (WxWxwx and Wxwxwx); and waxy (wxwxwx). Grains were harvested at physiological maturity and processed to yield ground grain and purified starch. Amylose content decreased with incremental increases of the waxy gene, but two doses were required to significantly reduce the percent amylose. The homozygous waxy grains had only traces of amylose. Incremental increases of the waxy gene increased both in vitro and in situ digestibility. Ruminal digestibility, as measured by nutrient disappearance or by gas production, was significantly greater in the homozygous waxy grain than other genotypes. Partial hydrolysis of the proteins in sorghum by pronase increased in vitro digestibility in all genotypes. Digestibility of pronase treated ground grain approached that of purified starch. Solubilization of the proteins in sorghum was affected by genotype with proteins in the homozygous waxy grain being more soluble (P<.05) than the homozygous non-waxy proteins. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science

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