Effects of citrus by-product supplementation on the intake and digestibility of urea plus sodium hydroxide-treated barley straw in goats

Sixteen castrated male goats of the Murciano-Granadina breed were used to determine the effect of citrus by-product supplementation on the intake and digestibility of urea + NaOH-treated barley straw. Barley straw was treated with urea (40 g kg(-1) DM) and sodium hydroxide (10 g kg(-1) DM) and was offered supplemented with citrus by-product at 0, 100, 200, 300 g DM animal/day in four digestibility trials in a completely randomised block design. Digestible organic matter intake was changed (P < 0.05) by a supplement of dried lemons. Dry matter and OM digestibilities were increased linearly (P < 0.001) by citrus by-product supplementation. There were ne differences (P> 0.05) in CP or fibrous fraction digestibilities among the four diets. The digestibility of treated straw was assessed for differences. Organic matter digestibility was different (P < 0.05) when urea + NaOH-treated straw was supplemented. At lower levels of supplementation a significant improvement in straw OM digestibility was found, but at higher levels of supplementation a slight negative effect was noted. When citrus by-products were added, the CP or fibrous fraction digestibilities of treated straw were not affected (P > 0.05). These results suggest that digestibility or intake of DM and OM in a diet based on urea + NaOH-treated barley straw could only be improved by supplementation at modest levels with cirrus by-product. (C) 1998 Elsevier Science B.V.