Effect of mechanical processing of cereals on rumen starch degradability
Although starch in cereal grain is almost completely digested in the whole digestive tract, the rate and extent of ruminal degradation and fermentation vary widely with grain source and cereal processing. The objective 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 mechanically processed wheat, barley and maize on ruminal degradation of starch. Standardized in sacco method was used to determine the degradation of starch in mechanically processed grains with incubation times of 0, 3, 6, 9, 16, 24, and 48 hours for maize, respectivelly. Significant differences of starch effective degradability (EDg) were determined among experimental feeds as well as dependence on particle size of feeds. Among cereals, wheat had the highest effective starch degradability (83.0–95.2%), the lowest was found for maize (52.1–76.1%). Effective degradability of starch was the highest for the smallest particles (≤ 1.4 mm), 95.2 for wheat, 91.2 for barley and 76.1% for maize. The effective degradability of starch was decreased with enlarging of particle size of used grains. These results indicate that optimal degree is coarsely grinding, because larger particles increased passage of starch to the duodenum.