Response to Cellulase Treatment of Silage and Replacement of Barley by Unmolassed Sugar Beet Pulp in the Diets of Growing Cattle

A timothy, meadow-fescue, red clover sward was ensiled in a farm scale silo to compare formic acid (FA) and cell wall degrading enzymes (E) (cellulase/glucose oxidase) as silage additive. In a feeding trial with 24 bulls, FA or E silage was offered ad libitum and supplemented with fish meal and either with barley (B), barley + unmolassed sugar beet pulp (BS) (1:1) or unmolassed sugar beet pulp (S). Both silages were well preserved, but fermentation in the E silage was more extensive. Dry matter (DM) intake was not significantly affected by additive or concentrate. The use of E silage reduced the digestibility of DM, organic matter (OM), N-free extract (NFE) (p<0.05) and crude fibre (p<0.001). The replacement of B by S resulted in a linear decrease in the digestibility of DM, OM (p<0.01), crude protein, and NFE (p<0.001). The digestibility of crude fibre increased linearly (p<0.001) with S, and more clearly with E than with FA silage. The live weight gain was 54 g/d greater with FA than E silage, and 60–70 g/d greater with BS than B or S alone (not significant differences). E silage seemed to need different supplementation than FA silage. The effects of silage additive and composition of supplement on the animal performance are discussed.