海兰灰与海兰褐蛋鸡免疫器官发育规律的研究OA

This study aimed to systematically compare the developmental patterns of major immune organs(spleen,bursa of Fabricius,and thymus)between Hy-Line Brown and Hy-Line Grey laying hens.A total of 138 newly hatched 1-day-old Hy-Line Grey and 138 Hy-Line Brown laying hens were selected and randomly divided into 2 groups according to breed,with 6 replicates per group and 23 birds per repli-cate.All birds were reared in cages.During the 63-day experimental period,one bird was randomly selected from each replicate cage every week to measure body weight and immune organ weights,for comparing the developmental patterns of immune organs between the two breeds.On this basis,the Gompertz model was applied to evaluate the developmental dynamics of the three immune organs.The results showed that the immune organ indices of both breeds presented a consistent trend of initial increase,subsequent decrease,and final stabilization.For Hy-Line Brown laying hens,the spleen and bursa of Fabricius indices peaked at 28 days of age,while the thymus index peaked at 21 days of age.For Hy-Line Grey laying hens,the spleen index peaked at 35 days of age,the bursa of Fabricius index peaked at 21 days of age,and the thymus index peaked at 28 days of age.Inter-breed comparison revealed that the spleen indices of the two breeds were significantly differ-ent at 7 and 28 days of age(P＜0.05).The bursa of Fabricius indices showed more substantial differences,with significant differences at 21,42,49 and 56 days of age(P＜0.05)and a highly significant difference at 35 days of age(P＜0.01).The thymus index only presented a highly significant difference between the two breeds at 56 days of age(P＜0.01).Gompertz model fitting results indicated minimal difference in spleen development between the two breeds:the inflection point age of spleen development was 23.460 6 days with an asymptotic weight of 2.571 7 g for Hy-Line Grey laying hens,and 22.077 3 days with an asymptotic weight of 2.721 2 g for Hy-Line Brown laying hens,with the two indicators being very close between breeds.The inflection point age of bursa of Fabricius development was 16.023 3 days for Hy-Line Grey laying hens and 7.577 2 days for Hy-Line Brown laying hens,which was delayed by approximately 9 days in the former.For the thy-mus,the inflection point age was 22.178 1 days with an asymptotic weight of 4.209 1 g for Hy-Line Grey laying hens,and 21.707 1 days with an asymptotic weight of 3.807 4 g for Hy-Line Brown laying hens;the inflection point ages were similar between breeds,while the as-ymptotic thymus weight was slightly higher in Hy-Line Grey laying hens.