Kegley E B, Spears J W, Brown T T
Department of Animal Science and Interdepartmental Nutrition Program, North Carolina State University, Raleigh 27695-7621, USA.
J Anim Sci. 1997 Jul;75(7):1956-64. doi: 10.2527/1997.7571956x.
Forty-eight Angus crossbred steers (263 +/- 2 kg initial BW) were blocked by weight and randomly assigned within weight group to treatment. Treatments consisted of control or .4 mg of supplemental Cr as Cr-nicotinic acid complex/kg of DM. Steers were fed diets containing 90% corn silage (DM basis) and 10% of a soybean meal-mineral-vitamin supplement. After 56 d on the dietary treatment, half of the steers in each treatment were transported 343 km and unloaded in an unfamiliar location. The next day, d 58, shipped steers were returned to the feedlot (50 km). On d 58 after shipped steers were returned to the feedlot, all steers were inoculated with infectious bovine rhinotracheitis virus (IBRV) intranasally. Average daily gain from d 0 to 80 was increased (P < .10) by supplemental Cr. There was a shipping x time interaction for serum cortisol concentrations. Shipping increased (P < .02) serum cortisol on d 58, but 7 d after transport there were no effects of shipping on serum cortisol. Transportation increased (P < .05) the ratio of neutrophils to lymphocytes. Supplemental Cr did not affect rectal temperature after the IBRV challenge or the antibody response to IBRV or porcine red blood cells. Immunoglobulin G antibody response to porcine red blood cells was decreased (P < .09) by shipping. Supplemental Cr as Cr-nicotinic acid improved ADG of growing steers, regardless of whether they had been stressed by shipping. Supplemental Cr did not affect any of the immune responses that were measured.
48头安格斯杂交阉牛（初始体重263±2千克）按体重进行分组，然后在体重组内随机分配处理方式。处理方式包括对照组或每千克干物质补充0.4毫克的铬（以烟酸铬复合物形式）。阉牛饲喂的日粮含有90%的玉米青贮料（干物质基础）和10%的豆粕 - 矿物质 - 维生素补充剂。在日粮处理56天后，每种处理方式下的一半阉牛被运输343公里并卸载到一个陌生的地点。第二天，即第58天，运输后的阉牛被送回饲养场（50公里）。在运输后的阉牛回到饲养场的第58天，所有阉牛经鼻内接种传染性牛鼻气管炎病毒（IBRV）。补充铬使从第0天到第80天的平均日增重有所增加（P < 0.10）。血清皮质醇浓度存在运输×时间的交互作用。运输使第58天的血清皮质醇升高（P < 0.02），但运输7天后运输对血清皮质醇没有影响。运输使中性粒细胞与淋巴细胞的比例升高（P < 0.05）。补充铬对IBRV攻毒后的直肠温度或对IBRV或猪红细胞的抗体反应没有影响。运输使对猪红细胞的免疫球蛋白G抗体反应降低（P < 0.09）。无论阉牛是否因运输而受到应激，以烟酸铬形式补充铬都能提高生长阉牛的平均日增重。补充铬对所测量的任何免疫反应均无影响。
