McGuinness M C, Cogburn L A
Department of Animal Science and Agricultural Biochemistry, College of Agricultural Sciences, University of Delaware, Newark 19717-1303.
Domest Anim Endocrinol. 1991 Oct;8(4):611-20. doi: 10.1016/0739-7240(91)90031-e.
The purpose of this study was to determine if exogenous insulin-like growth factor-I (IGF-I) would improve growth rate or body composition of young broiler chickens. Broiler cockerels were given a daily intramuscular (im) injection of sodium acetate buffer (buffer control), 100 or 200 micrograms recombinant-derived human IGF-I (rhIGF-I) per kg body weight from 11 to 24 days of age. Exogenous IGF-I did not affect the average daily gain, average daily feed consumption, or the gain-to-feed ratio of broiler chickens. Although daily injection of 200 micrograms/kg of rhIGF-I reduced (P less than 0.05) body ash content, there was no significant effect of IGF-I treatment on either body fat or protein content. Plasma GH levels were depressed (P less than 0.05) by chronic treatment with rhIGF-I. In contrast, plasma levels of T3 and T4 were not affected by rhIGF-I treatment. The half-life of rhIGF-I in plasma was determined at 25 days of age in naive control or chronically-injected chickens after a single intravenous dose of 50 micrograms rhIGF-I/kg. We found a single compartment, first-order disappearance pattern of rhIGF-I from chicken plasma. The half-life (t1/2) of rhIGF-I in plasma was similar (t1/2 = 32.5 min) for naive controls (injected once) or chronically-treated chickens which had received a daily injection of rhIGF-I (100 or 200 micrograms/kg) for 14 d. These data indicate that daily injection of IGF-I cannot be used to enhance growth performance or body composition of broiler chickens when given during the early growth period. The depression of plasma GH levels in rhIGF-I-injected chickens supports a negative-feedback role of IGF-I on pituitary GH secretion.
本研究的目的是确定外源性胰岛素样生长因子-I（IGF-I）是否会提高年轻肉鸡的生长速度或身体组成。从11日龄至24日龄，给肉用小公鸡每日进行一次肌肉注射醋酸钠缓冲液（缓冲液对照）、每千克体重100或200微克重组人IGF-I（rhIGF-I）。外源性IGF-I不影响肉鸡的平均日增重、平均日采食量或料重比。虽然每日注射200微克/千克的rhIGF-I会降低（P<0.05）身体灰分含量，但IGF-I处理对身体脂肪或蛋白质含量均无显著影响。长期用rhIGF-I处理会使血浆生长激素（GH）水平降低（P<0.05）。相比之下，rhIGF-I处理不影响血浆T3和T4水平。在25日龄时，给未接触过的对照鸡或长期注射过的鸡静脉注射一次50微克rhIGF-I/千克后，测定血浆中rhIGF-I的半衰期。我们发现rhIGF-I在鸡血浆中的消除模式为单室一级动力学。未接触过的对照鸡（单次注射）或每日注射rhIGF-I（100或200微克/千克）14天的长期处理鸡，血浆中rhIGF-I的半衰期相似（t1/2 = 32.5分钟）。这些数据表明，在生长早期每日注射IGF-I不能用于提高肉鸡的生长性能或身体组成。注射rhIGF-I的鸡血浆GH水平降低，支持了IGF-I对垂体GH分泌的负反馈作用。
