Arthington J D, Pate F M, Spears J W
University of Florida, Institute of Food and Agricultural Sciences, Range Cattle Research and Education Center, Ona 33865, USA.
J Anim Sci. 2003 Jun;81(6):1357-62. doi: 10.2527/2003.8161357x.
Two studies were conducted to evaluate the availability of dietary Cu offered to growing beef cattle consuming molasses-based supplements. In Exp. 1, 24 Braford heifers were assigned randomly to bahiagrass (Paspalum notatum) pastures (two heifers/pasture). Heifers were provided 1.5 kg of TDN and 0.3 kg of supplemental CP/heifer daily using a molasses-cottonseed meal slurry. Three treatments were randomly assigned to pastures (four pastures/treatment), providing 100 mg of supplemental Cu daily in the form of either CuSO4 (inorganic Cu) or organic-Cu. A third treatment offered no supplemental Cu (negative control). Heifer BW was collected at the start and end of the study. Jugular blood and liver samples were collected on d 0, 29, 56, and 84. In Exp. 2, 24 Brahman-crossbred steers were fed the same molasses-cottonseed meal supplement at the same rates used in Exp. 1. Steers were housed in individual pens (15 m2) with free-choice access to stargrass (Cynodon spp.) hay. Four Cu treatments were assigned to individual steers (six pens/treatment) providing 1) 10 ppm of Cu from an organic source; 2) 10 ppm Cu from Tri-basic Cu chloride (TBCC); 3) 30 ppm of Cu from TBCC; or 4) 30 ppm of Cu, a 50:50 ratio of TBCC and organic Cu. Body weights and jugular blood and liver samples were collected on d 0, 24, 48, and 72. In Exp. 1, liver Cu concentrations did not differ between heifers supplemented with inorganic and organic Cu. Each source resulted in increased (P < 0.05) liver Cu concentrations compared with the unsupplemented control. Plasma ceruloplasmin concentrations were higher (P < 0.05) for Cu-supplemented heifers, independent of Cu source. Heifer ADG tended (P = 0.11) to increase with Cu supplementation compared with the unsupplemented control. In Exp. 2, liver Cu was greater (P < 0.05) on d 24, 48, and 72 for steers consuming 30 vs. 10 ppm of Cu. Steers supplemented with organic Cu had lower DMI than steers supplemented with 10 or 30 ppm of TBCC. These data suggest that the inorganic and organic Cu sources evaluated in these studies were of similar availability when offered in molasses supplements. A dietary Cu concentration greater than 10 ppm might be necessary to ensure absorption in beef cattle fed molasses-based supplements.
开展了两项研究，以评估给食用糖蜜基补充料的生长肉牛提供的日粮铜的有效性。在试验1中，24头布拉福德小母牛被随机分配到巴哈雀稗（Paspalum notatum）牧场（每个牧场2头小母牛）。使用糖蜜 - 棉籽粕浆液，每天给小母牛提供1.5千克总可消化养分（TDN）和0.3千克补充粗蛋白（CP）/头。将三种处理随机分配到牧场（每个处理4个牧场），以硫酸铜（无机铜）或有机铜的形式每天提供100毫克补充铜。第三种处理不提供补充铜（阴性对照）。在研究开始和结束时收集小母牛的体重。在第0、29、56和84天采集颈静脉血和肝脏样本。在试验2中，24头婆罗门杂交阉牛以试验1中相同的速率饲喂相同的糖蜜 - 棉籽粕补充料。阉牛饲养在个体栏舍（15平方米）中，可自由采食狗牙根（Cynodon spp.）干草。将四种铜处理分配给个体阉牛（每个处理6个栏舍），提供1）来自有机源的10 ppm铜；2）来自三碱式氯化铜（TBCC）的10 ppm铜；3）来自TBCC的30 ppm铜；或4）30 ppm铜，TBCC和有机铜的比例为50:50。在第0、24、48和72天收集体重、颈静脉血和肝脏样本。在试验1中，补充无机铜和有机铜的小母牛肝脏铜浓度没有差异。与未补充的对照相比，每种来源都导致肝脏铜浓度增加（P < 0.05）。补充铜的小母牛血浆铜蓝蛋白浓度更高（P < 0.05），与铜源无关。与未补充的对照相比，补充铜的小母牛平均日增重（ADG）有增加的趋势（P = 0.11）。在试验2中，在第24、48和72天，采食30 ppm铜的阉牛肝脏铜含量高于采食10 ppm铜的阉牛（P < 0.05）。补充有机铜的阉牛干物质采食量（DMI）低于补充10或30 ppm TBCC的阉牛。这些数据表明，在这些研究中评估的无机和有机铜源在以糖蜜补充料形式提供时有效性相似。对于饲喂糖蜜基补充料的肉牛，可能需要大于10 ppm的日粮铜浓度以确保吸收。
