ENZYMES AS SILAGE ADDITIVES FOR GRASS CLOVER MIXTURES

Seven laboratory-scale experiments were carried out to study the effects of cellulases/hemicellulases on silage fermentation of herbage from mixed swards of timothy (Phleum pratense), meadow fescue (Festuca pratensis) and red clover (Trifolium pratense). Enzyme-treated silage (approximately 3500 HEC units kg-1 grass) reached a low pH sooner, had lower end pH, contained less NH3-N and more lactic acid than did the untreated silage (P < 0.05). Applied with an inoculant, these effects were even stronger. With easily ensiled crops (experiments 1, 2, 5 and 6) preservation was first of all improved by inoculation of lactic acid bacteria; however, for the low-sugar crops (experiments 3, 4 and 7) enzyme treatment was more significant. The enzymes derived from Aspergillus spp. gave more acetic acid than the enzymes from Trichoderma reesei. The Trichoderma enzymes liberated 4.8 g WSC kg-1 FM gamma-irradiated grass during 60 d at pH 4.3 (P < 0.05). On average, for all silages enzyme treatment increased the sum of residual sugar and fermentation products by 3.7 g kg-1 FM (21 g kg-1 DM) compared with the silages not treated with enzymes (P < 0.001). Enzyme treatment increased the instantly degradable part of the feed, but total in sacco and in vitro digestibilities were not affected.