Study On Copper Requirement Of Cashmere Goats

The aim of this study was to determine the copper requirements of Inner Mongolian White Cashmere Goats during the cashmere no-growing and growing period by the methods of comprehensive experiment and quantitative factorial model.Part one (during the cashmere no-growing period): Effects of supplementing different copper levels (0, 10, 20, 30 mg of Cu /kg of diet) in basal diet (7.38 mg of Cu /kg of diet) on rumen fermentation, blood copper status, nutrients metabolism and productive performance were studied to determine the copper requirement. Results showed that: (1)Copper supplementation in basal diet had no influence on culture fluid pH value and NH3-N and VFA concentrations, when incubated in vitro in 3,6,9, 12 and 24 hours (P>0.05); Copper Supplementation significantly affected rumen fluid pH value and VFA and Cu concentrations and ADF degradability of hay in rumen (.P<.05), but had no influence on NDF degradability of hay in rumen (P>0.05). (2)Copper Supplementation significantly increased plasma Cu concentration (PO.05), which had no significant difference among groups supplemented with 10, 20 and 30 mg of Cu /kg of diet(.P>0.05); serum Cp and SOD activities were increased with the increase of dietary Cu concentration; the correlation between serum Cp and SOD activities and plasma Cu concentration were follows respectively: y=69.97x-l9.323 (R2=0.891 P=0.0561), y=94.299x+90.11 (R2=0.6017 P=0.2243). (3)Dietary Cu levels had no influence on DM digestibility and N metabolism of Cashmere Goats during the cashmere no-growing period (P>0.05); NDF and ADF digestibilities of group supplemented with 10 mg of Cu /kg of diet were significantly higher than those of groups supplemented with 30 mg of Cu /kg of diet (P<0.05), but had no significant difference from those of groups supplemented with 0 and 20 mg of Cu /kg of diet (P>0.05); The correlation between intake Cu and excretion Cu was follow: y=0.8307x+7.7062 (R2=0.9673 P=0.0001); the maintenance Cu requirement of Cashmere Goats during the cashmere no-growing period was 7.71 g of Cu /kg of LW per day. (4)Dairy weight gain and feed conversion rate of groups supplemented with 0 and 30 mg of Cu /kg of diet (P<0.05), but had no significant difference from group supplemented with 20 mg of Cu /kg of diet (P>0.05); dietary Cu levels had no influence on dressing percentage, water content of carcass partition, relative weight of carcass partition based on empty body weight and Cu content of carcass partition (except liver) of Cashmere Goats (P>0.05); 1.63 mg of Cu /kg of weight gain and 8.09 mg of Cu /kg of fleece were deposited in the body of Cashmere Goats during the cashmere no-growing period. The optimal Cu requirement of Cashmere Goats during the cashmere no-growing period was 17.38 mg of Cu /kg of diet by the methods of comprehensive experiment, net Cu requirement was 0.3126 mg of Cu/d by the methods of quantitative factorial model.Part two (during the cashmere growing period): Effects of supplementing different Cu levels (0, 10, 20, 30 mg of Cu /kg of diet) in basal diet (7.46 mg of Cu /kg of diet) on rumen fermentation, nutrients metabolism and productive performance were studied to determine the copper requirement. Results showed-that: (1)Supplementing 10 mg of Cu /kg of diet in basal diet significantly decreased rumen fluid pH value (P<0.05), but increased rumen fluid NH3-N and VFA concentrations (P<0.05). (2)Dietary Culevel had no influence on feed intake, DM digestibility and N metabolism of Cashmere Goats during the cashmere growing period (P>0.05); NDF digestibility of groups supplemented with 10 and 20 mg of Cu /kg of diet were significantly higher than that of control group (P<0.05); dietary Cu level had no influence on ADF digestibility of Cashmere Goats during the cashmere growing period (P>0.05); the correlation between intake Cu and excretion Cu was follow: y=0.8704x+9.701 (R2=0.95477 P=0.0001); the maintenance Cu requirement of Cashmere Goats during the cashmere growing period was 9.07 g of Cu /kg of LW per day. (3)The weight gain...