Enzymes as silage additives 2. The effect of grass dry matter content on silage quality and performance in sheep

Eight grass silages were made from two contrasting varieties of perennial ryegrass, four silages each from a late-cut early-maturing (high dry matter, HDM) variety and from an early-cut, late-maturing (low dry matter, LDM) variety. The grass was ensiled without additive (untreated), or with formic acid, or with one of two enzyme mixtures of hemicellulases and cellulases (enzyme 1 and enzyme 2) for a period of 130 d.
Formic acid-treated silage had lower levels of lactic acid at both levels of dry matter than the other silages. Enzyme treatment of grass prior to ensilage resulted in reduced levels of cellulose, acid-detergent fibre and neutral-detergent fibre in LDM silages and lower acid-detergent fibre and neutral-detergent fibre in the HDM silages compared with the corresponding untreated and formic acid-treated silages. Voluntary intakes (g DM d^?1) of untreated and enzyme-treated silages were significantly ( P <0·01) lower at both digestibilities compared with formic acid-treated silages (LDM: untreated, 982; formic, 1069; enzyme 1, 868; enzyme 2, 937; HDM: untreated, 931; formic, 1027; enzyme 1, 943; enzyme 2, 914). The organic matter, carbohydrate and nitrogen digestibility coefficients of LDM silages were significantly ( P <0·001) higher than those of HDM silages. There were no significant differences in any component digestibility related to silage additive.
Comparison of digestibility coefficients for constituents of the LDM silages fed to sheep or steers showed no differences between species.