出雏前后蛋鸡和肉鸡血清中甲状腺激素水平的比较

用放射免疫分析法测定了出雏前后肉鸡（ＡＡ）和蛋鸡（伊莎）血清中总甲状腺激素（Ｔ３，Ｔ４）和游离甲状腺激素（ＦＴ３，ＦＴ４）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。今后 Ｔ３水平的变化在品种间有所不同，肉鸡从１日龄到１０日龄斩下降，１日与５日龄差异显著；恧旧鸡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

Comparison of T3,T4 and FT3,FT4 levels in the sera of perinatal layer and broiler chickens

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.