农昌Ⅱ号蛋鸡和AA肉鸡胸腺生长指标的比较研究

Comparative Study on Growth Index of Thymus between Nongchang Ⅱ Layers and AA Broilers

选用健康1日龄爱拔益加(AA)肉鸡100只、农昌Ⅱ号蛋鸡120只在相同的饲养管理条件下同期饲养。各取AA肉鸡和农昌Ⅱ号蛋鸡10只分别于1、3、5、7、14、21、28、35、42、49日龄时和1、5、7、14、21、28、35、42、56、70、84、98日龄时称重后解剖,取其胸腺称重,计算胸腺指数,制作石蜡切片,并在光镜下观察其形态。结果表明:AA肉鸡在5和42日龄时胸腺指数较大,分别为4.62和5.09;42日龄时胸腺皮质最厚;胸腺小体5日龄时达到最大。而农昌Ⅱ号蛋鸡在56日龄时胸腺指数较大,胸腺皮质最厚。将胸腺指数、胸腺皮质厚度、胸腺小体大小3个指标结合在一起进行分析得出,肉鸡在5和42日龄时免疫能力较强,而蛋鸡在56日龄时免疫力较强,并且蛋鸡的免疫高峰期要明显晚于肉鸡,这可能与蛋鸡的生长周期长于肉鸡有关。

A total of 100 one-day-old healthy AA broilers and 120 one-day-old healthy Nongchang Ⅱ layers were selected and reared under the same feeding and management conditions. Ten AA broilers were weighed and anatomized at the age of 1, 3, 5, 7,14, 21, 28, 35, 42, 49 days, and the thymus samples were collected and weighed. The thymus index was calculated and paraffin sections of thymus tissues were prepared. The histological structure of thymus tissues were observed under light microscope. Ten Nongchang Ⅱ layers were also weighed and anatomized at the age of 1, 5, 7, 14, 21, 28, 35, 42, 56, 70, 84, 98 days, and the subsequent treatment was the same with AA broilers. The results showed that for AA broilers, the higher thymus index was observed at the age of 5（4.62） days and 42（5.09） days, and the highest thickness of thymic cortex and the biggest size of thymic corpuscle was observed at the age of 42 days and 5 days respectively. For Nongchang Ⅱ layers, higher thymus index and the highest thickness of thymic cortex was observed at the age of 56 days. Combined the analysis results of thymus index, thymic corpuscle thickness and thymic cortex size, the AA broilers has higher immunity level at the age of 5 days and 42 days, the Nongchang Ⅱ layers has higher immunity level at the age of 56 days. The presence of immunity peak period of the layers was obviously later than the broilers, which was associated with the fact that the growth cycle of layers was longer than broilers.