Rojas L X, McDowell L R, Martin F G, Wilkinson N S, Johnson A B, Njeru C A
Animal Science Department, University of Florida, Gainesvile 32611, USA.
J Trace Elem Med Biol. 1996 Dec;10(4):205-9. doi: 10.1016/S0946-672X(96)80036-8.
A 12-week experiment was conducted to compare supplemental ZnMet, ZnSO4, and ZnO on Zn, Cu and metallothionein (MT) concentrations in various fluids and tissues of 32 yearling cattle. Supplemental Zn (360 mg per day) was fed for four weeks, withdrawn for four weeks, and then resumed for another four weeks. Mineral (Zn and Cu) concentrations were determined in serum, liver, pancreas, kidney, bone, bone marrow (metacarpus), hair, hoof and neck muscle (sterno mandibularis), and Zn only in erythrocytes, skin and cornea. Metallothionein levels were determined in liver, pancreas and kidney. There were no treatment differences (p > 0.05) in serum or erythrocyte Zn content for all days of collection. Serum Cu concentrations tended to decrease with all treatments. There were no treatment differences (p > 0.05) in Zn and Cu tissue concentrations and liver, kidney and pancreas MT concentrations. Tissue Cu concentrations did not drop in the supplemented treatments when compared to controls. At adequate levels of dietary Zn, bioavailability of supplemental Zn sources may be less important than under conditions of limited dietary Zn or if very high levels of supplemental Zn are fed.
进行了一项为期12周的试验，比较蛋氨酸锌、硫酸锌和氧化锌对32头一岁龄牛的各种体液和组织中锌、铜及金属硫蛋白（MT）浓度的影响。补充锌（每天360毫克）持续4周，停喂4周，然后再继续补充4周。测定了血清、肝脏、胰腺、肾脏、骨骼、骨髓（掌骨）、毛发、蹄和颈部肌肉（胸骨下颌肌）中的矿物质（锌和铜）浓度，以及红细胞、皮肤和角膜中的锌浓度。测定了肝脏、胰腺和肾脏中的金属硫蛋白水平。在所有采集日，血清或红细胞锌含量在各处理间均无差异（p>0.05）。所有处理组的血清铜浓度均有下降趋势。锌和铜的组织浓度以及肝脏、肾脏和胰腺中的金属硫蛋白浓度在各处理间无差异（p>0.05）。与对照组相比，补充处理组的组织铜浓度并未下降。在日粮锌水平充足时，补充锌源的生物利用率可能不如在日粮锌有限或补充锌水平非常高的情况下重要。
