Chronic copper toxicity in a dairy herd.

Area of Science:

• Veterinary Medicine
• Animal Nutrition
• Toxicology

Background:

• Copper is an essential trace element for cattle, but excessive levels can lead to toxicity.
• A commercial dairy ration was formulated with excessively high copper concentrations due to a feed company error.

Purpose of the Study:

• To investigate the effects of chronic copper toxicity in a commercial dairy herd.
• To determine the clinical signs and outcomes associated with excessive copper intake in dairy cattle.
• To evaluate the susceptibility of dairy cows, especially pregnant ones, to copper toxicity.

Main Methods:

• Analysis of feed concentrate to determine copper levels.
• Clinical observation of affected dairy animals.
• Post-mortem examination for signs of toxicity.
• Monitoring herd mortality and calf viability.

Main Results:

• Copper levels in the "as fed concentrate" ranged from 800 to 1,000 mg/kg.
• Acute toxicity signs included intravascular hemolysis and methemoglobinemia, resulting in five immediate deaths.
• An additional 39 cows died from debilitation and secondary infections, and 215 were culled due to poor condition and low milk production.
• Calf mortality from dams fed the toxic ration was approximately 50%.

Conclusions:

• Excessive copper in dairy rations can cause severe chronic toxicity, leading to significant mortality and economic losses.
• Dairy cows, particularly pregnant individuals, may exhibit increased susceptibility to copper toxicity.
• Current maximum allowable copper supplementation levels in dairy cattle diets warrant reexamination.