INTAKE AND DIGESTIBILITY OF SORGHUM SILAGE BY GOATS

This study investigated the effects of extraction of juice from forage sorghum on the final silage quality and nutritive value for goats. So rghum forage was prepared for ensiling in mini-silos either by choppin g (UCR) or by crushing and extraction of juice (CO), or by adding back 50% (C50) or 100% (C100) of juice to the extracted residue. Sorghum f orage was harvested at two different times (Periods 1 and 2) and ensil ed for 6 months and 4 months, respectively, prior to feeding. Treatmen t silages were fed ad libitum to Australian cashmere goats for 17 days during which intakes and digestibilities were determined. The dry mat ter (DM) content of the silage was low (UCR, 19.8%), and increased wit h juice removal (CO, 22.6%). There were no significant effects of pre- ensiling extraction of juice on water-soluble carbohydrate (WSC, 31 g kg-1 DM), total N (TN, 4.9 g kg-1 DM), lactic acid (66.3 g kg-1 DM, 71 % total acids) and acetic acid (20.6 g kg-1 DM) contents of silage. Al l silages were of high quality (pH < 3.7 5, ammonia N less than 6% TN) . There were no significant (P < 0.05) differences between silages in nutritive value for goats. Mean values (n = 16) for voluntary feed int ake were: 22.5 +/- 1.90 g DM kg-1 live weight (W) day-1 or 44.9 +/-4.1 7 g DM W-0.75 day-1. Mean values for digestibilities (%) were: DM 65.9 +/- 1.08, organic matter 67.4 +/- 1.05, neutral detergent fibre 62.0 +/- 1.94, nitrogen 43.0 +/- 2.40. It was concluded that whilst all sil ages were acceptable and of high nutritive value, the low N contents m ay have partly limited their utilisation by goats.