Alfaro E, Neathery M W, Miller W J, Crowe C T, Gentry R P, Fielding A S, Pugh D G, Blackmon D M
Department of Animal and Dairy Science, University of Georgia, Athens 30602.
J Dairy Sci. 1988 May;71(5):1295-300. doi: 10.3168/jds.S0022-0302(88)79686-1.
Sixteen intact male Holstein calves averaging 86 kg and 63 d of age were assigned randomly to four treatment groups. The four treatment diets contained .17, .67, 1.31, and 2.35% Ca on an as-fed basis. The resulting Ca:P ratios with P held constant at about .34% were .47:1, 1.92:1, 3.83:1, and 7.20:1. Calves were fed diets at 3% of their body weights for 4 wk. Magnesium in the bone ash and serum was lowered by the 2.35% Ca treatment. Serum inorganic P was also reduced by the highest Ca diet during the last 2 wk of the experiment. Liver had the highest concentration of Zn in calves fed .67% Ca, and the muscle from calves fed 1.31% Ca diet had the lowest amount of Zn. Copper was reduced in pancreas for 1.31% Ca diet, but Ca was highest in the muscle and heart at the .67% Ca treatment. Weight gains and feed efficiencies were not affected by Ca. Fecal pH was different among treatments and increased as Ca intake increased. Young growing dairy calves can adapt to a wide range of Ca intakes and Ca:P ratios and maintain a moderate growth rate for 4 wk. It appears that excessive dietary Ca may affect concentrations of Zn, Fe, Cu, and Mn in some body tissues, but the magnitude of the effect is relatively small.
16头平均体重86千克、年龄63天的健康雄性荷斯坦犊牛被随机分配到四个处理组。四种处理日粮按饲喂基础计算含钙量分别为0.17%、0.67%、1.31%和2.35%。在磷含量保持恒定在约0.34%的情况下，所得钙磷比分别为0.47:1、1.92:1、3.83:1和7.20:1。犊牛按体重的3%饲喂日粮，持续4周。2.35%钙处理降低了骨灰和血清中的镁含量。在实验的最后两周，最高钙日粮也降低了血清无机磷含量。在饲喂0.67%钙的犊牛肝脏中锌浓度最高，而在饲喂1.31%钙日粮的犊牛肌肉中锌含量最低。对于1.31%钙日粮，胰腺中的铜含量降低，但在0.67%钙处理时，肌肉和心脏中的钙含量最高。体重增加和饲料效率不受钙的影响。不同处理间粪便pH值不同，且随钙摄入量增加而升高。幼年生长奶牛犊能够适应广泛的钙摄入量和钙磷比，并在4周内保持适度的生长速度。看来，过量的日粮钙可能会影响某些身体组织中锌、铁、铜和锰的浓度，但影响程度相对较小。
