Lee C Y, Hunt D W, Gray S L, Henricks D M
Department of Animal, Dairy & Veterinary Sciences, Clemson University, SC 29634.
Domest Anim Endocrinol. 1991 Oct;8(4):481-9. doi: 10.1016/0739-7240(91)90017-e.
Fifteen Angus bulls and 15 Angus steers 9 months of age and 275 kg of body weight were bled at 20-min intervals over a 6-hr period and serum GH and IGF-I concentrations were measured by RIA. There were no differences between bulls and steers in the mean GH concentration, pulse frequency and amplitude when analyzed by the computer program PULSAR. Mean IGF-I concentration was not different between the two sex phenotypes, nor was there a significant correlation between the integrated IGF-I and GH concentrations. Subsequently, five bulls and five steers were selected from the 30 animals, full-fed a diet for growth in individual pens for 3 months and bled at 15-min intervals over a 24-hr period. Bulls tended to show a greater weight gain and feed conversion efficiency (P less than .10) than steers during the 3-month period. Serum GH concentrations had a pulsatile pattern in all animals with no apparent diurnal rhythm during the 24-hr bleeding. Although mean GH concentration was not different between the two sex phenotypes, bulls tended to have lower baseline levels (P less than .10) and greater peak amplitudes than steers. Serum IGF-I concentrations fluctuated within a two-fold concentration range, with no obvious pulsatility similar to that of GH. Mean IGF-I concentrations of each of the 10 animals were correlated with mean peak GH amplitudes (r = .79), but not with mean GH. These results suggest that gonadal hormone(s) modulates the GH secretory pattern and increases IGF-I secretion which may be related to the greater growth rate of bulls compared with steers.
选用15头9月龄、体重275千克的安格斯公牛和15头安格斯阉牛，在6小时内每隔20分钟采血一次，采用放射免疫分析法测定血清生长激素（GH）和胰岛素样生长因子-I（IGF-I）浓度。通过计算机程序PULSAR分析发现，公牛和阉牛的平均GH浓度、脉冲频率和幅度没有差异。两种性别表型之间的平均IGF-I浓度没有差异，IGF-I和GH的综合浓度之间也没有显著相关性。随后，从这30只动物中选出5头公牛和5头阉牛，在个体栏中自由采食生长日粮3个月，在24小时内每隔15分钟采血一次。在3个月的试验期内，公牛的体重增加和饲料转化效率往往高于阉牛（P<0.10）。在24小时的采血过程中，所有动物的血清GH浓度均呈现脉冲式变化，没有明显的昼夜节律。虽然两种性别表型之间的平均GH浓度没有差异，但公牛的基线水平往往较低（P<0.10），峰值幅度高于阉牛。血清IGF-I浓度在两倍的浓度范围内波动，没有明显的类似于GH的脉冲性。10只动物中每只的平均IGF-I浓度与平均GH峰值幅度相关（r = 0.79），但与平均GH浓度无关。这些结果表明，性腺激素调节GH的分泌模式并增加IGF-I的分泌，这可能与公牛比阉牛生长速度更快有关。
