Holland M D, Hossner K L, Tatum J D, King M E, Mauck H S, Odde K G
Dept. of Anim. Sci., Colorado State University, Fort Collins 80523.
J Anim Sci. 1988 Dec;66(12):3190-6. doi: 10.2527/jas1988.66123190x.
Serum samples and BW were obtained from 2-yr-old beef heifers, pregnancy with either single (SF, n = 12) or twin (TF, n = 7) fetuses, at 7-d intervals from d 190 of gestation until calving. Serum insulin-like growth factor I (IGF-I) concentrations of SF heifers gradually declined from d 190 (69.9 +/- 1.0 ng/ml) to d 263 (55.6 +/- .8 ng/ml), then exhibited a slight increase by d 277 (63.4 +/- 1.1 ng/ml). Serum IGF-I concentrations of TF heifers essentially paralleled, yet were lower (P less than .05) than, concentrations in SF heifers for all days tested except d 197 and 205. The SF heifers pregnant with heifer fetuses (n = 6) had higher IGF-I concentrations (P less than .1) than heifers pregnant with bull fetuses (n = 6) for all days tested except d 214 and 235. Instantaneous absolute growth rate (IGR) of SF heifers declined from 1.485 kg/d at d 190 to .257 kg/d by d 277. Rate of decline in IGR of TF heifers was much greater (P less than .0001). Correlations between serum IGF-I concentrations and IGR for SF and TF heifers were .79 (P less than .001) and .59 (P less than .05), respectively. These data suggest that number and sex of fetus influence maternal concentrations of IGF-I and that the combined growth rate of the dam and conceptus during gestation is related to serum IGF-I concentration.
从2岁的怀孕肉用小母牛获取血清样本和体重数据，这些小母牛怀有单胎（SF，n = 12）或双胎（TF，n = 7）胎儿，从妊娠第190天到产犊期间每隔7天采集一次。SF小母牛的血清胰岛素样生长因子I（IGF-I）浓度从第190天（69.9±1.0 ng/ml）逐渐下降至第263天（55.6±0.8 ng/ml），然后在第277天略有增加（63.4±1.1 ng/ml）。除第197天和第205天外，在所有测试日，TF小母牛的血清IGF-I浓度基本与SF小母牛平行，但低于SF小母牛（P<0.05）。在所有测试日，除第214天和第235天外，怀有雌性胎儿的SF小母牛（n = 6）的IGF-I浓度高于怀有雄性胎儿的小母牛（n = 6）（P<0.1）。SF小母牛的瞬时绝对生长率（IGR）从第190天的1.485 kg/d下降至第277天的0.257 kg/d。TF小母牛IGR的下降速率更大（P<0.0001）。SF和TF小母牛的血清IGF-I浓度与IGR之间的相关性分别为0.79（P<0.001）和0.59（P<0.05）。这些数据表明，胎儿的数量和性别会影响母体IGF-I的浓度，并且妊娠期间母体和胎儿的综合生长速率与血清IGF-I浓度有关。
