EFFECTS OF DRY-MATTER CONTENT ON THE NUTRITIVE-VALUE OF INDIVIDUALLY WRAPPED ROUND-BALE TIMOTHY SILAGE FED TO SHEEP

Thirty-two sheep (30.0 kg avg. BW) were used to study the effects of d ry-matter (DM) content at harvest on the nutritive value of timothy gr ass silages conserved as round bales of high (52.1 %, DM50), medium (3 9.9 %, DM40) and low (23.1 %, DM25) DM. Chopped grass of 24.4 % DM con served in a horizontal silo (HS) was used as a control. Gross energy, crude protein (CP) and acid detergent fibre (ADF) contents were simila r for all silages (P > 0.05). Neutral detergent fiber (NDF) contents d ecreased as DM of the silages decreased (P < 0.05). Acid detergent lig nin and ash contents were highest in HS and lowest in DM40 silages (P < 0.05). Silage pH and water-soluble carbohydrates decreased with decr easing DM of the silages (P < 0.05), while ammonia-N and lactate level s increased (P < 0.05). Acetate concentrations in round bales were low er than in HS silage (P < 0.05). Significant butyrate concentrations w ere detected only in DM25 silage. Round-bale silages were chopped befo re feeding and fed ad libitum. DM intake was 14.5 % higher for DM50 an d DM40 silages than for DM25 and HS silages (P < 0.001). Average daily gain and feed efficiency were higher for high-DM silages than for DM2 5 and HS silages (P < 0.01). Apparent digestibilities of NDF, cellulos e and crude fiber of the silages were similar, but DM, organic matter, energy and hemicellulose digestibilities were higher for HS than for DM25 silage. Apparent digestibilities of ADF and CP were higher for hi gh-DM silages than for DM25 and HS silages (P < 0.04). The results ind icate that to obtain good-quality silage, the DM content of round bale s should be 40-50 %. The better performance obtained with high-DM sila ges was indicative of a more efficient utilization of metabolizable en ergy for gain.