Performance, carcass characteristics, and lipid metabolism in growing and finishing Simmental steers fed varying concentrations of copper

An experiment was conducted to determine the effects of dietary copper (Cu) on performance, carcass characteristics, and lipid metabolism in Simmental steers. Thirty-six Simmental steers (329.3 +/- 11.4 kg) were stratified by weight and randomly assigned to treatments. Treatments consisted of the fo llowing: control (no supplemental Cu) and 10 or 40 mg Cu/kg DM from Cu sulf ate. Each treatment consisted of six replicate pens, with each pen containi ng two steers. A corn silage-soybean meal-based diet was fed for 56 d. Stee rs were then switched to a high concentrate diet. Performance was not affec ted by treatment during the growing or finishing phases. Plasma Cu concentr ations were higher (P < 0.05) in steers receiving supplemental Cu by d 56 o f the growing phase and remained higher (P < 0.05) at all 28-d sampling per iods during the finishing phase. Liver Cu concentrations were higher (P < 0 .001) in steers receiving supplemental Cu at the end of the growing phase a nd on d 84 and at the end of the finishing phase. Steers supplemented with 40 mg Cu had higher (P < 0.001) liver Cu concentrations than those suppleme nted with 10 mg Cu/kg DM. Serum and longissimus muscle cholesterol concentr ations were similar between treatments. Longissimus muscle and backfat fatt y acid composition was similar between treatments. These results indicate t hat Cu supplementation given to Simmental steers increased Cu status but ha d no effect on performance, carcass characteristics, or lipid or cholestero l metabolism.