Verde L S, Trenkle A
J Anim Sci. 1987 Feb;64(2):426-32. doi: 10.2527/jas1987.642426x.
Blood samples were taken from four large- and four small-frame steers each month for 12 mo to study the effect of size on plasma hormone concentrations in cattle from 5 to 17 mo of age. The rate of gain and daily feed intake were 45% (P less than .05) and 51% (P less than .001) greater for the large steers. The large-frame steers had higher mean concentrations of growth hormone (P less than .001), insulin (P less than .06), thyroxine (P less than .06) and cortisol (P less than .002). The concentration of growth hormone was highest in the young cattle (P less than .01) and gradually declined with increasing age. Insulin concentrations were lowest in the young cattle (P less than .01) and gradually increased with age. The results of this study suggested that there are differences in hormone concentrations that are related to size rather than being the result of differences in physiological maturity of different breeds of cattle.
在12个月的时间里，每月从4头大体型和4头小体型的阉牛身上采集血样，以研究体型对5至17月龄牛血浆激素浓度的影响。大体型阉牛的增重率和每日采食量分别比小体型阉牛高45%（P<0.05）和51%（P<0.001）。大体型阉牛的生长激素（P<0.001）、胰岛素（P<0.06）、甲状腺素（P<0.06）和皮质醇（P<0.002）的平均浓度更高。生长激素浓度在幼牛中最高（P<0.01），并随年龄增长逐渐下降。胰岛素浓度在幼牛中最低（P<0.01），并随年龄增长逐渐升高。本研究结果表明，激素浓度存在差异，这种差异与体型有关，而非不同品种牛生理成熟度差异的结果。
