Andrews A H
Res Vet Sci. 1975 Mar;18(2):134-8.
Twenty-nine British Friesian cattle fed the same diet, slaughtered at various weights and including bulls, steers (castrated males) and females (heifers) were examined. The stage of their rostral tooth development was recorded both visually and radiographically. Insufficient animals were present in each sex and slaughter weight treatment group to allow any comparison between them. When the data for each sex were compared, no statistically significant differences were seen between the mean ages at which bulls, steers and heifers attained each stage of dental development as determined from their radiographs. The results for all 29 cattle were then combined. This combined data showed a relationship between age and those stages of tooth formation which could be differentiated by examination of the X-ray films. As most phases of tooth formation occurred within well defined limits, it is suggested that radiographs of rostral tooth development might be used to estimate the age of cattle.
对29头食用相同饲料、在不同体重时屠宰的英国弗里斯兰牛进行了检查，这些牛包括公牛、阉牛（去势雄性）和母牛（小母牛）。通过视觉和X射线摄影记录了它们吻部牙齿的发育阶段。每个性别和屠宰体重处理组中的动物数量不足，无法对它们进行任何比较。当比较每个性别的数据时，从X射线片确定的公牛、阉牛和小母牛达到牙齿发育各阶段的平均年龄之间没有统计学上的显著差异。然后将所有29头牛的数据合并。这些合并数据显示了年龄与通过X射线片检查可区分的牙齿形成阶段之间的关系。由于牙齿形成的大多数阶段发生在明确的范围内，因此建议吻部牙齿发育的X射线片可用于估计牛的年龄。
