O'Kelly J C, Wallace A L
Biol Neonate. 1979;36(1-2):55-62. doi: 10.1159/000241207.
The patterns of plasma concentrations of thyroxine (T4), triiodothyronine (T3) and cholesterol were determined in tropically adapted (ZX) and temperate (SH) breeds of cattle in the first 6 days of their lives in a tropical environment. T4 concentrations were high at birth and fell to within normal adult values at 6 days of age. In contrast, plasma cholesterol levels were low at birth and increased daily to the highest values on day 6. T3 levels increased from birth to maximum values at 12 h after birth and then declined progressively. The T4/T3 molar ratios were high at birth and decreased to lower values on day 2. T4 and cholesterol levels were higher (p less than 0.001) in ZX than in SH calves, and in calves born in winter were higher (p less than 0.001) in females than in males. There were significant (p less than 0.001) animals within-breed differences in all parameters. The results are discussed with reference to the use of physiological and biochemical indices for the early selection of cattle suited to tropical conditions.
在热带环境中，对热带适应性品种（ZX）和温带品种（SH）的犊牛出生后前6天的血浆甲状腺素（T4）、三碘甲状腺原氨酸（T3）和胆固醇浓度模式进行了测定。T4浓度在出生时较高，在6日龄时降至成年正常水平。相反，血浆胆固醇水平在出生时较低，且每日升高，在第6天达到最高值。T3水平从出生时开始升高，在出生后12小时达到最大值，然后逐渐下降。T4/T3摩尔比在出生时较高，在第2天降至较低值。ZX犊牛的T4和胆固醇水平高于SH犊牛（p<0.001），且冬季出生的犊牛中，雌性的T4和胆固醇水平高于雄性（p<0.001）。所有参数在品种内的动物之间均存在显著差异（p<0.001）。结合生理和生化指标在早期选择适合热带条件的牛方面的应用对结果进行了讨论。
