出雏前后蛋鸡和肉鸡血清中甲状腺激素水平的比较

Comparison of T 3,T 4 and FT 3,FT 4 levels in the sera of perinatal layer and broiler chickens

用放射免疫分析法测定了出雏前后肉鸡 （ Ａ Ａ） 和蛋鸡 （伊莎） 血清中总甲状腺激素 （ Ｔ３、 Ｔ４） 和游离甲状腺激素（ Ｆ Ｔ３、 Ｆ Ｔ４ ） 的水平。结果表明： 肉鸡和蛋鸡血清总 Ｔ３水平在１４胚龄和１８胚龄时较低， １日龄时显著上升， 肉鸡表现尤为突出。出雏后 Ｔ３ 水平的变化在品种间有所不同， 肉鸡从１日龄到１０日龄逐渐下降， １日龄与５日龄差异显著 （ Ｐ＜ ００１）； 而蛋鸡１日龄至５日龄 Ｔ３水平显著升高。除１日龄肉鸡 Ｔ３ 水平显著高于蛋鸡外， 其它日龄蛋鸡 Ｔ３ 水平显著高于肉鸡（ Ｐ ＜ ００１）。血清中 Ｔ４水平从１４胚龄到１８胚龄上升显著； 出壳后肉鸡血清中 Ｔ４ 水平逐渐上升， 而蛋鸡 Ｔ４ 水平则逐渐下降， 正好与 Ｔ３ 水平变化相反。肉鸡血清中 Ｆ Ｔ３ 水平高于蛋鸡， ５日龄时差异极显著 （ Ｐ ＜ ００１）， 与生长速度呈正相关； 而 Ｆ Ｔ４ 水平正好相反， 蛋鸡显著高于肉鸡 （ Ｐ ＜ ００５）。

Serum levels of T 3,T 4 and free T 3(FT 3),free T 4(FT 4)were measured in perinatal broiler and layer chickens using radioimmunoassay.Blood samples were taken on embryonic days(E)14 and 18 and neonatal days(D)1,5 and 10.Serum T 3 levels were found low at E14 and E18 but increased dramatically at hatching.In the broiler,T 3 levels increased 10 fold from E18 to D1.After hatching,the developmental changes of T 3 levels displayed different patterns between two strains of chicken.T 3 level in broilers went down from D1 to D10,while the opposite was up for the layer.Layer chickens displayed a significantly higher value of T 3 than broilers at all age groups investigated except D1.T 4 in both strains of chicken gradually rose during embryonic period.After hatching,T 4 levels kept going up in the broiler but went down in layers,which is inversely correlated with the changes of T 3.At D5,serum levels of FT 3 were significantly higher in the broiler than in the layer,showing a positive correlation with the growth rate.In contrast,the FT 4 in layers was higher than that in broilers on D5 of posthatching.