Digestion of whole-crop grain silage starch in ruminants

Abstract

The effect of cereal species (oat, triticale, rye and barley) and stage of maturity of plants at harvest (heading - H, milk - M, and milk-dough - MD) on starch digestion was studied. An in vivo digestibility trial was conducted on 12 wethers. Starch ruminal degradability was determined in situ and postruminal digestibility by the mobile nylon bag technique. Starch from whole-crop cereal silages was nearly completely digested in the digestive tract. Its digestibility significantly increased as plants matured from H to M stage (P<0.05) and then was stable. With the exception of triticale, starch from silages made at H or M stages of maturity was entirely digested within 16 h of incubation in the rumen. In stage MD the highest contents effraction A (94.6%) and starch ERD (98.1%) were found for oat silage (P