Copper and lipid metabolism in beef cattle: a review.

Results from experiments investigating Cu metabolism in ruminants indicate that Cu is involved in lipid metabolism. Copper supplementation ranging from 10 to 40 mg of Cu/kg of DM to high-concentrate finishing diets decreased subcutaneous adipose tissue deposition and decreased cholesterol concentrations but increased unsaturated fatty acid composition of LM. Serum norepinephrine tended to be greater in Cu-supplemented steers after a 24-h feed withdrawal and at 2 h postfeed consumption, potentially explaining the reduction in subcutaneous adipose tissue deposition. However, when exogenous norepinephrine was administrated, serum NEFA concentrations were less in Cu-supplemented steers, possibly due to the nonsupplemented control steers having a greater subcutaneous adipose tissue depth at slaughter relative to Cu-supplemented steers. Furthermore, in vitro basal and epinephrine-stimulated lipolytic rates of subcutaneous adipose tissue were greater in Cu-supplemented steers relative to controls. These data indicate that that Cu may influence lipogenic or lipolytic function in subcutaneous adipose tissue. In an attempt to further investigate the effect of Cu on lipid metabolism, lipogenic, lipolytic, and homeostatic mechanisms related to Cu are currently being studied. Recent data indicate that genes involved in bovine liver Cu homeostasis are correlated with Cu transporter protein gene expression in the bovine liver. Therefore, the overall intent of this review is to discuss possible mechanisms whereby Cu may affect lipid metabolism in ruminants.