Arthington J D, Spears J W
University of Florida--IFAS, Range Cattle Research and Education Center, Ona, FL 33865, USA.
J Anim Sci. 2007 Mar;85(3):871-6. doi: 10.2527/jas.2006-518. Epub 2006 Oct 23.
The objective of this study was to investigate the effect of supplemental tribasic copper chloride (Cu(2)(OH(3))Cl; TBCC) vs. Cu sulfate (CuSO(4)) on Cu status and voluntary forage DMI in growing heifers. Two 90-d experiments were conducted using 48 non-pregnant, crossbred heifers (24 heifers/experiment; 355 +/- 10.7 and 309 +/- 9.9 kg for Exp. 1 and 2, respectively). In each experiment, 3 supplemental Cu treatments were randomly allocated to heifers in individual pens consisting of (1) 100 mg of Cu/d from CuSO(4), (2) 100 mg of Cu/d from TBCC, or (3) 0 mg of Cu/d. The 2 experiments differed by the form of supplement used to deliver the Cu treatments (corn- vs. molasses-based supplements for Exp. 1 and 2, respectively). Supplements were formulated and fed to provide equivalent amounts of CP and TDN daily but differed in their concentration of the Cu antagonists, Mo (0.70 vs. 1.44 mg/kg), Fe (113 vs. 189 mg/kg), and S (0.18 vs. 0.37%) for corn- and molasses-based supplements, respectively. All heifers were provided free-choice access to ground stargrass (Cynodon spp.) hay. Jugular blood and liver biopsy samples were collected on d 0, 30, 60, and 90 of each experiment. Heifer BW was collected on d 0 and 90. Heifer ADG was not affected by Cu treatment (average = 0.22 +/- 0.11 and 0.44 +/- 0.05 kg for Exp. 1 and 2, respectively; P > 0.20). In Exp. 1, heifers provided supplemental Cu, independent of source, had greater (P < 0.05) liver Cu concentrations on d 60 and 90 compared with heifers provided no supplemental Cu. In Exp. 2, average liver Cu concentrations were greater (P = 0.04) for heifers receiving supplemental Cu compared with heifers receiving no Cu; however, all treatments experienced a decrease in liver Cu concentration over the 90-d treatment period. Plasma ceruloplasmin concentrations did not differ in Exp. 1 (P = 0.83) but were greater (P = 0.04) in Exp. 2 for heifers receiving supplemental Cu compared with heifers receiving no Cu. In Exp. 1, voluntary forage DMI was greater (P < 0.05) for heifers provided supplemental Cu, independent of source, compared with heifers provided no Cu. In contrast, voluntary forage DMI was not affected (P > 0.10) by Cu supplementation in Exp. 2. These data imply that CuSO(4) and TBCC are of similar availability when offered to growing beef heifers in both corn- and molasses-based supplements. However, corn- and molasses-based supplements appear to affect Cu metabolism differently. These impacts may affect voluntary forage DMI in growing beef heifers.
本研究的目的是调查补充碱式氯化铜（Cu₂(OH)₃Cl；TBCC）与硫酸铜（CuSO₄）对生长中的小母牛铜状态和自愿采食量的影响。使用48头未怀孕的杂交小母牛进行了两项为期90天的试验（每项试验24头小母牛；试验1和试验2中的小母牛体重分别为355±10.7千克和309±9.9千克）。在每项试验中，将3种补充铜处理随机分配到各个栏中的小母牛，处理包括：（1）每天从CuSO₄中补充100毫克铜，（2）每天从TBCC中补充100毫克铜，或（3）每天不补充铜。两项试验的不同之处在于用于提供铜处理的补充剂形式（试验1和试验2分别为基于玉米和基于糖蜜的补充剂）。补充剂经过配方设计并投喂，以每天提供等量的粗蛋白和可消化总养分，但基于玉米和基于糖蜜的补充剂中铜拮抗剂钼（0.70对1.44毫克/千克）、铁（113对189毫克/千克）和硫（0.18对0.37%）的浓度不同。所有小母牛均可自由采食碎星星草（狗牙根属）干草。在每项试验的第0、30、60和90天采集颈静脉血和肝脏活检样本。在第0天和第90天测量小母牛体重。小母牛的平均日增重不受铜处理的影响（试验1和试验2的平均日增重分别为0.22±0.11千克和0.44±0.05千克；P>0.20）。在试验1中，与未补充铜的小母牛相比，补充铜的小母牛（无论铜源如何）在第60天和第90天的肝脏铜浓度更高（P<0.05）。在试验2中，与未补充铜的小母牛相比，补充铜的小母牛的平均肝脏铜浓度更高（P=0.04）；然而，在90天的处理期内，所有处理的肝脏铜浓度均有所下降。试验1中血浆铜蓝蛋白浓度没有差异（P=0.83），但在试验2中，与未补充铜的小母牛相比，补充铜的小母牛的血浆铜蓝蛋白浓度更高（P=0.04）。在试验1中，与未补充铜的小母牛相比，补充铜的小母牛（无论铜源如何）的自愿采食量更大（P<0.05）。相比之下，试验2中补充铜对自愿采食量没有影响（P>0.10）。这些数据表明，当在基于玉米和基于糖蜜的补充剂中提供给生长中的肉牛小母牛时，CuSO₄和TBCC的有效性相似。然而，基于玉米和基于糖蜜的补充剂似乎对铜代谢的影响不同。这些影响可能会影响生长中的肉牛小母牛的自愿采食量。
