Clapper J A, Clark T M, Rempel L A
Department of Animal and Range Sciences, South Dakota State University, Brookings 57007, USA.
J Anim Sci. 2000 Oct;78(10):2581-8. doi: 10.2527/2000.78102581x.
The purpose of this research was to determine whether serum concentrations of steroids, IGF-I, and relative amounts of serum IGF-binding proteins (IGFBP) differ in growing boars (n = 11), barrows (n = 11), and gilts (n = 12) from 70 to 140 d of age. Pigs of similar age and weight were housed in pens of three or four and given ad libitum access to a 17% CP corn-soy diet and water. Pigs were weighed and blood samples were collected every 14 d beginning at 70 d of age. Serum concentrations of IGF-I and steroids were determined by RIA and relative amounts of IGFBP were determined by ligand blot analysis. By 84 d of age and continuing through 140 d of age, mean serum concentrations of IGF-I were greater (P < .05) in boars than in barrows or gilts. Relative amounts of 46-kDa IGFBP3 and 28-kDa IGFBP-4 were similar (P > .05) among pigs at 70 d of age; however, boars and barrows had greater (P < .05) relative amounts of 24-kDa IGFBP-4 and 41-kDa IGFBP-3 than gilts. Relative amounts of IGFBP-2 were greater (P < .01) in barrows than in gilts or boars at 70 d of age. From 84 d of age through 140 d of age, relative amounts of both forms of IGFBP-3 and the 28-kDa IGFBP-4 were greater (P < .05) in boars than in gilts or barrows. Relative amounts of IGFBP2 were greater (P < .05) in barrows than in gilts or boars at 98 d of age, but by 140 d of age relative amounts were greater (P < .05) in boars and barrows than in gilts. Mean serum concentrations of estradiol-17beta were similar (P > .05) between gilts and boars at 70 d of age, but by 98 d of age, and continuing through 140 d of age, mean serum concentrations of estradiol-17beta were greater (P < .05) in boars than in gilts. Mean serum concentrations of testosterone in boars increased (P < .05) with increasing age and were greatest at 128 and 140 d of age. Serum concentrations of testosterone were negatively correlated (P < .01) with relative amounts of serum IGFBP-2 but positively correlated (P < .01) with serum concentrations of IGF-I and estradiol-17beta. Serum concentrations of estradiol-17beta were positively correlated (P < .01) with serum concentrations of IGF-I in boars. Changes in serum concentrations of IGF-I and relative amounts of IGFBP resulting from changes in serum concentrations of estradiol-17beta and testosterone may contribute to growth differences observed among sexes.
本研究的目的是确定70至140日龄的生长公猪（n = 11）、阉公猪（n = 11）和后备母猪（n = 12）的血清类固醇、IGF-I浓度以及血清IGF结合蛋白（IGFBP）的相对含量是否存在差异。将年龄和体重相近的猪以三或四头为一组饲养在栏中，自由采食17%粗蛋白的玉米-大豆日粮和饮水。从70日龄开始，每14天对猪称重并采集血样。通过放射免疫分析（RIA）测定IGF-I和类固醇的血清浓度，通过配体印迹分析测定IGFBP的相对含量。到84日龄并持续至140日龄时，公猪的平均血清IGF-I浓度高于阉公猪或后备母猪（P < 0.05）。70日龄时，猪之间46 kDa的IGFBP3和28 kDa的IGFBP-4相对含量相似（P > 0.05）；然而，公猪和阉公猪的24 kDa的IGFBP-4和41 kDa的IGFBP-3相对含量高于后备母猪（P < 0.05）。70日龄时，阉公猪的IGFBP-2相对含量高于后备母猪或公猪（P < 0.01）。从84日龄至140日龄，公猪的两种形式的IGFBP-3和28 kDa的IGFBP-4相对含量均高于后备母猪或阉公猪（P < 0.05）。98日龄时，阉公猪的IGFBP2相对含量高于后备母猪或公猪（P < 0.05），但到140日龄时，公猪和阉公猪的相对含量高于后备母猪（P < 0.05）。70日龄时，后备母猪和公猪的雌二醇-17β平均血清浓度相似（P > 0.05），但到98日龄并持续至140日龄时，公猪的雌二醇-17β平均血清浓度高于后备母猪（P < 0.05）。公猪的睾酮平均血清浓度随年龄增长而升高（P < 0.05），在128和140日龄时最高。睾酮的血清浓度与血清IGFBP-2的相对含量呈负相关（P < 0.01），但与IGF-I和雌二醇-17β的血清浓度呈正相关（P < 0.01）。公猪中，雌二醇-17β的血清浓度与IGF-I的血清浓度呈正相关（P < 0.01）。由雌二醇-17β和睾酮血清浓度变化导致的IGF-I血清浓度和IGFBP相对含量的变化可能是造成不同性别生长差异的原因。
