Effects Of Dietary Copper Sources On Copper Metabolism And Cellulose Degradation In Sheep

The study was conducted to investigate the effects of dietary copper sources on copper metabolism and cellulose degradation in sheep. The solubility of Cu from Cu oxide, Cu sulfate, tri-basic copper chloride, Cu lysine, and Cu proteinate was determined in deionized water, dilute acid or buffer. Twenty crossbred (Poll Dorset X Small Tail Han-yang) wethers were used to assess the effects of copper sources on concentration of plasma copper in sheep. All sources provided 8 mg of added Cu/kg of DM. Copper sulfate and Cu lysine were almost completely soluble in all solvents. However, CuO was completely insoluble in all solvents. Tri-basic copper chloride had low solubilities in water and buffer but was soluble in acid. Copper proteinate had high solubilities in water and acid but was insoluble in buffer. The effects of copper sources on concentration of plasma copper did not differ among copper sources (P > .05). The concentration of plasma copper reached a peak 2 hr after intake across treatments. Tri-basic copper chloride, Cu lysine, and Cu proteinate may be suitable for sheep. Wethers with permanent rumen fistula were used to determine concentration of plasma copper, activity of cuproenzyme, apparent digestibility of copper, and disappearance rates of DM and NDF of Chinese wildrye in sheep given different copper supplements to diets with low or high molybdenum. All sources provided 16 mg of added Cu/kg of DM. Molybdenum was added as sodium molybdate. The results indicate sheep fed supplemental Cu from Cu sulfate, tri-basic copper chloride, Cu lysine, or Cu proteinate had greater (P < .05) plasma Cu concentrations and TCA soluble Cu concentrations than those fed supplemental Cu from Cu oxide when diets contained low molybdenum. However, when diets with high molybdenum was given, sheep fed supplemental Cu from tri-basic copper chloride, Cu lysine, or Cu proteinate had greater (P < .05) plasma Cu concentrations and TCA soluble Cu concentrations than those fed supplemental Cu from Cu oxide or Cu sulfate. Experiments were performed to assess the effects of dietary supplements of copper and sulfur on copper metabolism and digestion of roughage in sheep fed low or high molybdenum diets in Latin-square design. Copper as tri-basic copper chloride or Cu lysine, S as sodium sulfate were added and provided 0, 6, 12, 18 mg of Cu/kg of DM and 0%, .05%, .10%, .15% sulfur respectively and molybdenum was given as sodium molybdate providing 0, 10 mg of Mo/kg of DM. The results showed that there were no effects (P > .05) of dietary sulfur on digestion, absorption, or metabolism of tri-basic copper chloride or Cu lysine in sheep fed diets with low molybdenum, but concentration of TCA soluble Cu decreased (P < .05) and that of TCA insoluble Cu increased (P < .05) with increasing dietary S in sheep fed diets with high molybdenum. Concentrations of plasma Cu and TCA soluble Cu increased (P < .05) with increasing dietary Cu in sheep fed diets with low or high molybdenum. No differences were significant (P > .05) in apparent digestibility of copper, activities of cuproenzymes, disappearance rates of dry matter and neutral detergent fiber of Chinese wildrye with dietary supplements of copper or sulfur. The results of this study indicate that tri-basic copper chloride, Cu lysine, and Cu proteinate may be ideal dietary copper sources for sheep. It appears that there were no effects of copper sources on cellulose degradation in sheep and activities of cuproenzymes can not reflect status of copper nutrition of sheep.