Efficacy, distribution and faecal excretion of copper oxide wire particles in a novel bolus in red deer (Cervus elaphus)

Abstract

AIM: To determine the efficacy of a novel copper oxide wire particle (COWP) formulation in elevating concentrations of copper (Cu) in the liver and serum of red deer (Cervus elaphus), and to investigate the distribution of particles in the gastrointestinal tract and the rate of their excretion in faeces.

METHODS: Mixed-age red deer hinds were allocated to three groups (n=10 per group) on the basis of pre-treatment liver Cu concentrations. Groups 1 and 2 were treated orally with a 10-g COWP bolus on Days 0 and 30, respectively, while the remaining group served as an untreated control. Animals were slaughtered on Day 60, when blood and liver samples were collected for determination of Cu concentrations. An additional group of 18-month-old red deer hinds (n=20) were treated orally with a 10-g COWP bolus, and four were slaughtered on each of Days 1, 5, 15, 30 and 60 after treatment. The gastrointestinal tract was secured between compartments below the oesophagus and contents rinsed until sedimentation of particles was complete. The sediment was oven-dried and COWP were separated and weighed. Faeces were collected continuously from four additional animals held in metabolism cages for 4 days after treatment, sub-sampled daily, and COWP recovered.

RESULTS: Mean liver Cu concentrations at slaughter were 80, 597 and 447 µmol/kg for controls and hinds treated 30, and 60 days previously, respectively. Corresponding mean serum Cu concentrations were 7.7, 12.9 and 11.9 µmol/L, respectively. Liver and serum Cu concentrations were higher in both treatment groups than in untreated control animals (p<0.001). COWP were found in all compartments of the gastrointestinal tract measured, for at least 15 days, and in the rumen/reticulum and abomasum for at least 60 days post-administration. The highest rate of recovery overall was from the rumen/reticulum. Mean weight of COWP recovered from faeces was 0.09 g during the first 24 h and 0.94 g over the first 4 days following administration.

CONCLUSION: The COWP bolus tested resulted in elevated mean liver Cu concentrations for at least 60 days compared with control animals. The majority of COWP were found in the rumen/reticulum, where recovery was possible for at least 60 days. About 10% of particle weight was excreted in the faeces within 4 days of administration.

CLINICAL SIGNIFICANCE: The test bolus was efficacious in deer, elevating mean liver and serum Cu concentrations 30 and 60 days after treatment. Variation in faecal excretion may explain between-animal differences in efficacy.

KEY WORDS:

• Deer
• copper
• copper oxide wire particles
• efficacy
• distribution
• liver
• serum

Acknowledgements

We wish to thank members of the Massey University Deer Research Group for technical assistance; and Chris and Christine Pullar for allowing us to work with their animals, and for helping with animal handling. This project was funded by Parnell Laboratories, New Zealand Ltd.