CONDENSED TANNINS ARE ONLY PARTIALLY RESPONSIBLE FOR VARIATIONS IN NUTRIENT DIGESTIBILITIES OF SORGHUM GRAIN CULTIVARS

Nitrogen-corrected true metabolizable energy (TME(n)) and true amino a cid digestibility values were determined, using cecectomized cockerels , for 20 sorghum [Sorghum bicolor (L.) Moench] cultivars that ranged i n catechin equivalent (CE) percentages from 0 to 3.88. There were sign ificant (P less than or equal to 0.01) overall inverse relationships b etween CE content and (1) the individual digestibilities of lysine, me thionine, threonine, isoleucine, leucine, valine, phenylalanine, histi dine, and arginine; (2) the mean digestibility of essential amino acid s; (3) the mean digestibility of nonessential amino acids; and (4) TME (n) values. In contrast to these overall trends, several cultivars of similar condensed tannin content had markedly different nutrient diges tibilities. The dissimilarity of protein digestibilities in sorghum ge notypes of similar tannin content was confirmed by subjecting samples of the ground grains to in vitro pepsin digestion with subsequent visu alization of the undigested proteins by SDS-PAGE. The present work sug gests that other components besides tannins are responsible for variat ions in the availability of nutrients in sorghum.