Variation in apparent component digestibility of barley in the rat from the core collection of the USDA National Small Grains Collection

Abstract

More information on the range in available genetic variation of barley component digestion in vivo would benefit barley breeders developing feed quality cultivars for non-ruminants. The purpose of this study was to measure variation in component digestibility of barley genotypes from the core collection of the USDA National Small Grains Collection using the rat as a model animal. Two rat growth and digestion studies were conducted with diets based on a total of 11 barley genotypes grown in the same year at the same location. The mean coefficient of total tract apparent digestibility (CTTAD) of components ranged from 0.796 to 0.908 for DM, from 0.992 to 0.999 for starch, from 0.832 to 0.852 for crude protein, and from −0.002 to 0.269 for ADF. Rats fed diets based on two-row head types had greater ( P<0.05) CTTAD of DM and lesser CTTAD of ADF than rats fed six-row head types. Rats consuming hulless barleys had higher ( P<0.05) protein efficiency ratio, feed efficiency, CTTAD of DM and CTTAD of starch compared with rats fed covered barleys. Digestibility of ADF was higher for diets based on two-row hulless and six-row covered barleys than for diets based on two-row covered and six-row hulless barleys. Substantial variation in barley component digestibility existed in the rat from the USDA National Small Grains Collection barley genotypes evaluated, and this variation in feed quality could be exploited to improve barley cultivars for feed quality.