Effects of Dietary Copper on Ruminal Fermentation, Nutrient Digestibility and Fibre Characteristics in Cashmere Goats * (Report‪)‬

ABSTRACT : Thirty-six 1.5 year-old Inner Mongolian White Cashmere wether goats (body weight 28.14 [+ or -] 1.33 kg) were used to determine the effects of dietary copper (Cu) concentration on ruminal fermentation, nutrient digestibility and cashmere fibre characteristics. Wethers were fed a basal diet (containing 7.46 mg Cu/kg DM) that was supplemented with either 0 (control), 10, 20 or 30 mg Cu/kg DM. To ensure full consumption, animals were fed restrictedly with 0.75 kg feed (DM) in two equal allotments per day. The results indicated that: (1) supplemental 10 mg Cu/kg DM in the basal diet significantly (p0.05) decreased ruminal fluid pH value and total VFA concentrations were significantly (p0.05) increased on all Cu treatment groups. (2) Cu supplementation had no influence on DM intake and digestibility of DM, CP and ADF (p0.05); however, NDF digestibility of groups supplemented with 10 and 20 mg Cu/kg DM were significantly higher than that of the control group (p0.05). Apparent absorption and retention of copper were decreased with increasing level of supplementation. (3) 20 mg Cu/kg DM treatment significantly (p0.05) improved cashmere growth rate, but cashmere diameter was not affected by Cu supplementation (p0.05). In conclusion, supplementation of cashmere goats with Cu at the rate of 10 to 20 mg/kg DM in the basal diet resulted in some changed rumen fermentation and was beneficial for NDF digestibility, while supplementation of 20 mg Cu/kg DM improved cashmere growth. Collectively, the optimal supplemental Cu level for cashmere goats during the fibre growing period was 20 mg/kg DM (a total dietary Cu level of 27.46 mg/kg DM). (Key Words : Copper, Rumen Fermentation, Nutrient Digestibility, Cashmere Fibre Characteristics) INTRODUCTION