Possible subclinical hepatopathy after copper supplementation in farmed red deer

Abstract

AIM: To determine the effect of parenteral supplementation with Cu on the activities of hepatic enzymes in deer with adequate concentration(s) of Cu in liver and serum. METHODS: Male red deer aged 12 months were given either 0.8 or 1.6 mg of Cu/kg of a S/C injectable Cu formulation or no Cu (n=10/group) on 03 December 2007 (Day 0). Concentration of Cu in liver was measured in biopsies taken on Days −13 and 17, and that in serum on Days 0, 1, 3 and 17. Liver enzymes, gamma-glutamyl transferase (GGT) and glutamate dehydrogenase (GDH), were measured in serum on Days 3 and 7. Deer were weighed on Days 0 and 17. RESULTS: The mean concentration of Cu in liver was 203 (range 50–460) μmol/kg fresh weight (FW) on Day −13 and that in serum was 14.8 (range 7.8–25.0) μmol/mL on Day 0. Concentrations of Cu in liver were adequate (>100 μmol/kg FW) in 25/30 deer. Injection with 0.8 mg of Cu/kg resulted in elevated mean concentrations of Cu in serum to 20.3 (range 14–26) and 17.4 (range 12–26) μmol/mL on Days 1 and 3 respectively, whereas 1.6 mg/kg resulted in mean concentrations of Cu in serum of 26.7 (range 20–42) and 19.3 (range 16–25) μmol/mL on Days 1 and 3 respectively (p<0.05). The mean concentration of Cu in liver on Day 17 was 1,460 (range 1,000–2,300) after injection with 0.8 mg/kg, 1,666 (range 1,100–2,200) after 1.6 mg/kg, and 280 (range 75–420) μmol/kg FW in controls. Injection with 1.6 mg Cu/kg, but not 0.8 mg/kg, resulted in an increase in the activity of GGT (p=0.05), and in 4/10 deer a marked change in the activity of GDH, between Day 3 and Day 7, indicating that injection of copper induced a moderate degree of subclinical hepatopathy. Mean liveweight gain (g/day) to Day 17 was 105.9 (range −176 to 411) in control animals and 64.7 (range −59 to 176) 64.7 and −61.7 (range −294 to 117) in deer given 0.8 and 1.6 mg/Cu/kg respectively (p=0.003). CONCLUSIONS: S/C administration of 1.6 mg of Cu/kg in deer which had adequate Cu status pre-treatment resulted in elevated activities of GGT and GDH in serum, indicating hepatopathy, and both this dose rate and 0.8 mg/kg resulted in reduced liveweight gain post-treatment compared with untreated controls. CLINICAL SIGNIFICANCE: Cu supplementation should not be administered when the Cu status of deer is adequate or unknown.