Experimentally induced chronic copper toxicity in cattle

Area of Science:

• Veterinary Science
• Animal Nutrition
• Toxicology

Background:

• Copper (Cu) is an essential trace element for cattle, but excessive intake can lead to toxicity.
• Understanding safe and toxic levels of oral copper supplementation is crucial for livestock health and productivity.

Purpose of the Study:

• To determine the effects of different oral copper sulphate dosages on Bonsmara cattle.
• To identify the threshold for subclinical liver damage and copper toxicity in cattle.

Main Methods:

• Eight Bonsmara bulls and eight heifers were allocated to four groups, receiving varying daily oral copper doses (0.6, 10, or 20 mg/kg body mass/day) or a control over 745 days.
• Clinical signs, serum enzyme activities (gamma-glutamyltransferase, aspartate aminotransferase), blood urea nitrogen, plasma mineral concentrations, and live mass gain were monitored.
• Liver and kidney mineral concentrations were analyzed post-mortem.

Main Results:

• Cattle receiving 10 mg/kg body mass/day or higher showed clinical signs and required euthanasia.
• Subclinical liver damage and eventual copper toxicity were observed at sustained oral doses of 12 mg/kg body mass/day or greater.
• Low oral copper doses (<= 0.6 mg/kg body mass/day) appeared tolerable long-term, assuming no other copper sources or adverse mineral interactions.

Conclusions:

• Continuous oral exposure to copper doses >= 12 mg/kg body mass/day can lead to subclinical liver damage and copper toxicity in cattle.
• Oral copper doses <= 0.6 mg/kg body mass/day are likely safe for indefinite periods in cattle, provided other copper sources and adverse mineral interactions are absent.