EFFECT OF A COMMERCIAL ENZYME PREPARATION ON ALFALFA SILAGE FERMENTATION AND PROTEIN DEGRADABILITY

A commercial enzyme preparation (trade name Clampzyme) containing cellulases, hemicellulases and glucose oxidases was tested for ensiling of alfalfa at three dry matter levels, 16% and 22% unwilted and 28% wilted, in comparison with untreated control and formic acid treated silages. On average the enzyme-treated silages had a lower pH (by 14.6% at P = 0.000), lower crude fibre content (by 16.0% at P = 0.000) and ammonia concentration (by 20.3% at P = 0.017), and higher water-soluble carbohydrates (by 115% at P = 0.000) and crude protein (by 11.8% at P = 0.006) content compared with the control. The enzyme treatment had an undesirable effect on the silage protein preservation, increasing the buffer soluble nitrogen (by 16.9% at P = 0.014) and the free amino acid nitrogen (by 25.5% at P = 0.007) content compared with the untreated control. The enzyme-treated silages tended to have lower trichloroacetic acid insoluble nitrogen (by 7.8% at P = 0.080) than the control. The degradability of the silage protein in vitro (4-h incubation) was higher (by 28.0% at P = 0.006) for the enzyme-treated silages compared with the control. The same trend was observed in sacco where the difference over the control silages decreased from 11.9% (P = 0.001) at the 1 h to 8.2% (P = 0.001) at 24 and 4.3% (P = 0.001) at 48 h of rumen incubation. In these experiments no protective effect of the formic acid on silage protein degradability in vitro or in sacco was observed. In conclusion, the enzyme treatment had a positive effect on alfalfa silage fermentation, in particular on reducing the crude fibre content and preserving the soluble sugars. An increase in rumen degradability of the silage protein in vitro and in sacco was observed with the rapidly degradable fraction of the protein being the most affected.