Engle T E, Spears J W, Armstrong T A, Wright C L, Odle J
Department of Animal Science and Interdepartmental Nutrition Program, North Carolina State University, Raleigh 27695-7621, USA.
J Anim Sci. 2000 Apr;78(4):1053-9. doi: 10.2527/2000.7841053x.
We conducted an experiment to determine the effects of dietary copper (Cu) source and level on carcass characteristics, longissimus muscle fatty acid composition, and serum and muscle cholesterol concentrations in steers. Sixty Angus and Angus x Hereford steers were stratified by weight and initial liver Cu concentration within a breed and randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu); 2) 20 mg Cu/kg DM from Cu sulfate (CuSO4); 3) 40 mg Cu/kg DM from CuSO4; 4) 20 mg Cu/kg DM from Cu citrate; 5) 20 mg Cu/kg DM from Cu proteinate; and 6) 20 mg Cu/kg DM from tribasic Cu chloride. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high-concentrate diet. Equal numbers (n = 5) of steers per treatment were slaughtered after receiving the finishing diets for either 101 or 121 d. Serum cholesterol was not affected by treatment during the growing phase but was decreased (P < .05) in steers supplemented with Cu by d 84 of the finishing period and remained lower (P < . 05) at subsequent sampling periods. Longissimus muscle cholesterol concentration tended to be reduced (P < .11) by Cu supplementation. Hot carcass weight and backfat were lower (P < .05) in animals receiving supplemental Cu. However, Cu-supplemented and control steers had similar marbling scores. Longissimus muscle polyunsaturated fatty acid concentrations (18:2 and 18:3) were increased (P < .07) and saturated fatty acid concentrations tended (P < . 11) to be reduced by Cu supplementation. These results indicate that as little as 20 mg of supplemental Cu/kg diet can reduce backfat and serum cholesterol and increase muscle polyunsaturated fatty acids in steers fed high-concentrate diets.
我们进行了一项实验，以确定日粮铜（Cu）来源和水平对阉牛胴体特性、背最长肌脂肪酸组成以及血清和肌肉胆固醇浓度的影响。六十头安格斯和安格斯×赫里福德阉牛按品种内体重和初始肝脏铜浓度进行分层，并随机分配到各处理组。处理组包括：1）对照组（不添加铜）；2）硫酸铜（CuSO4）提供的20毫克铜/千克干物质；3）硫酸铜提供的40毫克铜/千克干物质；4）柠檬酸铜提供的20毫克铜/千克干物质；5）蛋白铜提供的20毫克铜/千克干物质；6）碱式氯化铜提供的20毫克铜/千克干物质。以玉米青贮料 - 豆粕为基础的日粮喂养56天。然后阉牛转为高浓缩日粮。在接受育肥日粮101天或121天后，每个处理组宰杀数量相等（n = 5）的阉牛。生长阶段血清胆固醇不受处理影响，但在育肥期第84天时，添加铜的阉牛血清胆固醇降低（P < 0.05），且在随后的采样期保持较低水平（P < 0.05）。添加铜使背最长肌胆固醇浓度有降低趋势（P < 0.11）。接受补充铜的动物热胴体重和背膘厚度较低（P < 0.05）。然而，添加铜的阉牛和对照阉牛大理石花纹评分相似。添加铜使背最长肌多不饱和脂肪酸浓度（18:2和18:3）升高（P < 0.07），饱和脂肪酸浓度有降低趋势（P < 0.11）。这些结果表明，对于采食高浓缩日粮的阉牛，日粮中添加低至20毫克/千克的铜就能降低背膘厚度和血清胆固醇，并增加肌肉多不饱和脂肪酸含量。
