ENSILING OF WHOLE-CROP WHEAT WITH CELLULASE-HEMICELLULASE BASED ENZYMES .2. EFFECT OF CROP GROWTH-STAGE AND ENZYME ON SILAGE INTAKE, DIGESTIBILITY AND LIVE-WEIGHT GAIN BY STEERS

Whole-crop winter wheat was harvested at the mealy-ripe and hard-dough stages of grain development corresponding to crop dry matter: (DM) co ntents of 427 g DM kg(-1) and 678 g DM kg(-1) respectively. Crop from each harvest was dither untreated or treated with one of two enzyme ad ditives (Clampzyme or FSO2) and then ensiled for at least 60 days, in 7 t capacity bunker silos. Clampzyme was applied at 667 ml t(-1) DM an d FSO2 at 1000 ml t(-1) DM. The six silages were fed individually and ad libitum to 270-300 kg live weight (W) Hereford X Friesian steers ov er 56 days [d], using 8 animals per silage. Steers were also fed 0.5-0 .8 kg d(-1) of soyabean-mineral supplement. Digestibility was measured by total collection of faeces using 5 steers per treatment. All silag es were well-preserved. For the parameters measured, there was no inte raction (P > 0.05) between crop growth stage and enzyme treatment. Cro p growth stage did not affect (P > 0.05) silage intake (mealy-ripe, 25 .5 g DM (kg W d)(-1); hard-dough, 25.3 g DM (kg W d)(-1)). Both diet o rganic matter digestibility (P < 0.05) (694, 665 g kg(-1)) and growth rate (P < 0.01) (0.9, 0.8 kg d(-1))were higher in steers fed mealy-rip e compared to hard-dough silage. Enzyme additives did not affect (P > 0.05) intake, digestibility or growth rate.