Oberbauer A M, Krook L, Hogue D E, Currie W B, Thonney M L
Department of Animal Science, Cornell University, Ithaca, NY 14853.
J Nutr. 1988 Aug;118(8):976-81. doi: 10.1093/jn/118.8.976.
The effects of excess dietary calcium on bone growth were quantified in 44 ewes fed ad libitum diets that contained one of four levels of dietary calcium (0.37, 0.56, 1.13 and 1.80%) and 0.42% phosphorus. Animals were slaughtered at one of six ages, circulating concentrations of hormones and minerals were measured and bone morphometry was evaluated. None of the diets impaired normal bone growth of the metacarpal as evaluated by overall length, cortical index and growth plate width. Circulating plasma concentrations of calcium and gastrin increased as dietary calcium levels increased, but all values were within the normal range for sheep. Plasma phosphorus was unaffected by the level of dietary calcium. Diet had no affect on T3, T4 or estradiol-17 beta. Age significantly (P less than 0.05) affected the metacarpal length, growth plate width and circulating calcium and phosphorus. The metacarpal in these ewes was 95% of mature length by 172 d of age. Attainment of mature length preceded growth plate closure by slightly over 300 d. These results demonstrate that elevated dietary calcium levels do not adversely influence bone growth and that the presence of an intact growth plate does not infer that further bone growth will occur.
在44只自由采食的母羊中，对过量膳食钙对骨骼生长的影响进行了量化。这些母羊的日粮含有四种水平的膳食钙（0.37%、0.56%、1.13%和1.80%）之一以及0.42%的磷。在六个年龄阶段之一对动物进行屠宰，测量激素和矿物质的循环浓度，并评估骨形态计量学。通过掌骨的总长度、皮质指数和生长板宽度评估，没有一种日粮损害掌骨的正常骨骼生长。随着日粮钙水平的增加，循环血浆钙和胃泌素浓度升高，但所有值均在绵羊的正常范围内。血浆磷不受日粮钙水平的影响。日粮对T3、T4或雌二醇-17β没有影响。年龄显著（P<0.05）影响掌骨长度、生长板宽度以及循环钙和磷。这些母羊的掌骨在172日龄时达到成熟长度的95%。达到成熟长度比生长板闭合早略超过300天。这些结果表明，日粮钙水平升高不会对骨骼生长产生不利影响，并且完整生长板的存在并不意味着会有进一步的骨骼生长。
