Utilization of Processed Sorghum Grain Proteins by Steers

Abstract

Four yearling half-sib Angus steers with permanent abomasal fistulas were used to study the effects of different methods of processing on the utilization of sorghum grain proteins. Processing treatments studied were: dry grinding, reconstitution and grinding, steam flaking and micronizing. Reconstitition and steam flaking resulted in enhanced ruminal conversion of sorghum protein to bacterial protein, as determined from lysine and leucine ratios, while micronizing resulted in decreased ruminal conversion, compared to dry grinding. Digestion of abomasal proteins, in the intestines was very similar on all treatments. The data indicate that reconstitution and steam flaking sorghum grain increase the biological value of the grain proteins through improved conversion to higher quality bacterial protein in the rumen, but micronizing apparently lowers biological value through decreased ruminal conversion of the grain protein to microbial protein, relative to conventional grinding.