The effect of high dietary Cu on health, growth performance, and Cu status in young goats

An experiment was conducted to determine the effect of high dietary Cu on growth performance and Cu status in goat kids. Fifteen Boer × Spanish goat kids (4–5 months of age; average BW = 21.3 ± 0.7 kg) were housed in individual pens and randomly assigned to three different treatments. Treatments consisted of (1) control (no additional Cu), (2) 100 mg Cu/d and (3) 200 mg Cu/d from an inorganic source Cu sulfate. Copper was placed in gelatin capsules and inserted in the esophagus via balling gun before AM feeding. Animals were fed ad libitum twice a day a 70:30 grain:hay diet to meet daily requirements of growing kids according to NRC [NRC, 1981. Nutrient requirements of domestic animals. Nutrient requirements of goats: angora, dairy and meat goats in temperate and tropical countries, No. 15, National Research Council, National Academy of Science, Washington, DC]. Feed intake and refusals were monitored daily and intake was adjusted weekly for 14 weeks. Body weight was recorded after 4 h withdrawals from feed and water, for 2 consecutive days every 2 weeks. Vital signs and blood samples were obtained every 2 weeks. After 14 weeks, sorbitol dehydrogenase (SDH) levels were determined and animals were slaughtered. Liver, bile, longissimus muscle (LM) and kidney samples were obtained postmortem. Copper supplementation had no effect (P > 0.05) on respiration rate, heart rate, rectal temperature, or serum SDH activity. Average daily gain over 10 weeks was improved with 100 mg Cu intake (quadratic, P = 0.01). Average daily feed intake decreased linearly (linear, P = 0.05) as Cu increased in the diet with the control group consuming a higher grain:hay ratio in the diet (linear, P = 0.03). Gain efficiency was higher (quadratic, P = 0.02) with 100 mg Cu group when compared to control and 200 mg Cu groups. Liver and fecal Cu concentrations increased (linear, P = 0.0001) as Cu increased in the diet; however, serum, bile, and kidney Cu concentrations did not differ. These data indicate that high level of Cu fed to Boer × Spanish goat kids at 100 mg/d can enhance average daily gain and gain efficiency without eliciting Cu toxicity.