DIGESTIBILITY OF GRASS-SILAGE

Grass silage is a very important ruminant winter feed in the Netherlands. The nutritive value of grass silage can, however, vary considerably. Varying influences attributed to grass growth stage at harvesting, botanical composition, harvesting conditions, ensiling processes and post-ensiling events complicate the accurate prediction of the feeding value based on laboratory analyses. Fifty grass silages were tested in digestibility trials with wethers. The feeds tested included mainly wilted silages of varying dry matter content as well as silages treated with cell-wall degrading enzymes. The accuracy of feed evaluation was studied using laboratory analyses, including cell-wall analyses, incubation in vitro with rumen fluid and the enzymatic procedure. A comparison was made between these results and the current and recently suggested procedures for prediction of digestibility of grass silage.