Plouzek C A, Trenkle A
Department of Animal Science, Iowa State University, Ames 50011.
Domest Anim Endocrinol. 1991 Jan;8(1):73-9. doi: 10.1016/0739-7240(91)90041-h.
The influence of age, sex and castration on plasma concentrations of insulin-like growth factor-I (IGF-I) and other metabolic hormones related to growth was studied in cattle. Plasma was sampled from bulls, steers, heifers, and ovariectomized heifers at 20-min intervals for 12 hr at 5, 8, 12, and 15 mo of age. Plasma samples from each animal taken during each 12-hr period were composited for analysis of IGF-I, testosterone, total estrogens, thyroxine, triiodothyronine, insulin, and glucose. The mean plasma IGF-I concentration in all cattle increased from 61.6 to 158.6 ng/ml as the animals aged (p less than .01). Over all ages, bulls had greater concentrations of IGF-I than steers, heifers, or ovariectomized heifers (P less than .01). Bulls also had higher concentrations of testosterone (P less than .01) and total estrogens (P less than .01). Triiodothyronine concentration was greater in ovariectomized heifers than in bulls (P less than .01) or steers (P less than .05). Females had higher concentrations of thyroxine than males (P less than .01). Concentrations of triiodothyronine in the cattle were greater (P less than .01) during the winter and early spring as compared with the summer. Concentrations of insulin and glucose were not influenced by sex or castration; however, insulin increased in all cattle with age (P less than .01). The mean increase in IGF-I concentration with age within each of the four groups was associated with an increase in concentration of plasma insulin but the differences due to sex were not related to differences in insulin.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了年龄、性别和去势对牛血浆中胰岛素样生长因子-I（IGF-I）及其他与生长相关的代谢激素浓度的影响。在5、8、12和15月龄时，每隔20分钟从公牛、阉牛、小母牛和去卵巢小母牛采集血浆，持续12小时。将每只动物在每个12小时时间段采集的血浆样本混合，用于分析IGF-I、睾酮、总雌激素、甲状腺素、三碘甲状腺原氨酸、胰岛素和葡萄糖。随着动物年龄增长，所有牛的血浆IGF-I平均浓度从61.6 ng/ml增加到158.6 ng/ml（P<0.01）。在所有年龄段，公牛的IGF-I浓度高于阉牛、小母牛或去卵巢小母牛（P<0.01）。公牛的睾酮（P<0.01）和总雌激素浓度也更高（P<0.01）。去卵巢小母牛的三碘甲状腺原氨酸浓度高于公牛（P<0.01）或阉牛（P<0.05）。雌性的甲状腺素浓度高于雄性（P<0.01）。与夏季相比，牛在冬季和早春的三碘甲状腺原氨酸浓度更高（P<0.01）。胰岛素和葡萄糖浓度不受性别或去势影响；然而，所有牛的胰岛素浓度随年龄增加（P<0.01）。四组中每组IGF-I浓度随年龄的平均增加与血浆胰岛素浓度增加相关，但性别差异与胰岛素差异无关。（摘要截短至250字）
