The association of hepatic copper concentration with hepatocyte health and oxidative stress in dairy cattle

"Copper is sequestered in liver of all animals, and particularly so in ruminants, as an apparent reserve supply to provide for nutritional needs during times of insufficient dietary intake. Copper has poor dietary bioavailability in cattle and therefore copper is often supplemented in the diets of dairy cattle and over-supplementation can occur. Excessive hepatic copper accumulation in dairy cattle has been of growing concern in recent years. Despite this, the impact of elevated copper concentrations on bovine hepatocytes, short of fulminant toxicosis, is still not well understood. The overarching goal of this research is to provide veterinarians and nutritionists with a better interpretation of liver copper concentrations and their relevance to animal health, especially when they are above expected reference values but below fulminant toxic concentrations. The direct aim of this study is to determine the association between hepatic copper concentrations and biomarkers for subclinical hepatocellular damage in dairy cattle. Hepatocellular damage will be assessed by histological analysis, measurement of liver leakage enzymes in serum, and systemic and hepatic markers of oxidative stress. If such an association is found, it will suggest that super-nutritional, but sub-toxic hepatic copper concentrations may be a risk factor for disease in dairy cattle"--Page ii.