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.

KEY WORDS:

• Copper
• toxicity
• deer
• hepatopathy
• liver enzymes
• gamma-glutamyl transferase
• glutamate dehydrogenase
• weight gain

Acknowledgements

The assistance of the Deer Research Group at Massey University is gratefully acknowledged, particularly Kathryn Goodwin-Ray, as is the support and assistance of the staff at New Zealand Veterinary Pathology Hamilton and Palmerston North. The authors would also like to thank Kevin Lawrence for statistical support and advice.

Notes

*Non-peer-reviewed