Studies on the Nutritional Value of Sorghum Grains with Varying Tannin Contents for Chicks: 1. Growth Studies

Abstract

Studies were conducted on the performance of chicks fed diets containing either a bird resistant sorghum (BR64) or an intermediate bird resistant sorghum (NK300) as compared with that observed when chicks were fed diets containing a bird susceptible sorghum (RS610) or corn as the cereal grain. Chicks fed sorghum BR64 exhibited poorer growth and feed conversion as compared with chicks fed sorghum RS610. In general, the performance of chicks fed sorghum NK300 was intermediate between the other two sorghums. Chicks fed the corn diets consistently exhibited superior weight gains and, in some cases, superior feed conversion as compared with chicks fed the various sorghum containing diets.Weight gains and feed conversion were decreased when tannic acid was added to the corn, sorghum RS610 and sorghum NK300 diets to the level found in the sorghum BR64 diet. The performance of chicks fed the corn and sorghum RS610 diets with added tannic acid was still superior to those of chicks fed the BR64 or the NK300 diet with added tannic acid. These results suggest that the poor performance of chicks fed the latter two diets was not due solely to the presence of tannic acid.Chicks adapted to a high tannin diet during 1–21 days of age and fed the high tannin diet from 21 to 35 days showed weight gains of 54.7% and an increase in feed required per gram gain of 60.6% as compared with adapted chicks fed a low tannin diet from 21 to 35 days. Chicks fed a low tannin diet from 1 to 21 days of age and switched to a high tannin diet from 21 to 35 days exhibited weight gains of 43.5% and an increase in feed required per gram gain of 85.1% as compared with non-adapted chicks fed a low tannin diet from 21 to 35 days.Similar weight gains and feed conversions were noted when essential amino acids were added to corn and sorghum RS610 diets to raise the levels to those found in the other grain. A significant improvement in weight gain and feed conversion as compared with chicks fed an unsupplemented diet was noted when chicks were fed a sorghum BR64 diet with essential amino acids added up to the levels found in corn. Weight gain, but not feed conversion, of chicks fed the supplemented sorghum BR64 diet was equal to that of chicks fed the unsupplemented RS610 diet, but chick performance was poorer than that observed with an unsupplemented corn diet, a supplemented corn diet or a supplemented RS610 diet.