Effect of physical processing of cereals on rumen crude protein degradability

Abstract

The extent of crude protein (CP) degradation in the rumen is an important parameter for prediction of protein supplying for the rumen microorganisms as well as the supply of the ruminant animal with amino acids. Therefore the protein degradability of the feedstuffs becomes an essential characteristics in determining the protein value of the feeds. The protein degradation in the rumen varies considerably between feeds and within feeds. Different chemical or physical treatments of the feed can influence the degradability also. The objectives of this study was to determine the effect of particle size (≤ 1.4, 1.5-2.5, 2.6-3.0 and > 3,0 mm) of processed wheat, barley and maize on ruminal degradability and the parameters of effective crude protein degradability by in sacco method. Among cereals, wheat had the highest effective crude protein degradability (76.4-85.9 %), the lowest was found in maize (28.0-58.6 %). Reduction in particle size increased degradability of crude protein in all grains. Effective degradability was the highest for the smallest particles (≤ 1.4 mm), 85.9 % for wheat, 79.8 % for barley and 58.6 % for maize. These results indicate that optimal degree is coarsely grinding, because larger particles caused the lower ruminal degradability and increased passage of undegraded CP to the duodenum.