Researches About The Development Characteristics Of Immune Organs Between Jianchang Duck And Meat Duck

One of the main factors to determine the state of development of immune organs in animal is inheritance, and in present duck production, the breeding breed meat duck with high manual selection tends to exhibit less strong as native breed in the ability of disease resistance. To investigate the development characteristics of immune organs in meat duck and native duck, we choosed a kind of local duck (named as Jianchang duck) and a kind of meat duck breed to research. In our study, we compared the development characteristics of immune organs at different stages of the two differernt kinds ducks. During the ducks’growth period, we detected the immune organ index and observed the lymphocyte differentiation status by histological analysis. At the same time, we explored the development of immune organs and their effections on the immunity functions by testing the physiological indexes of blood including the content of INF-y and globulin by ELISA,and detected key genes expression levels involved in the immune response such as TLR4, IL-2ad IgM. The results we obtained were listed as follows:1. During the whole gowth period of duck, the thymus, spleen and the bursa of Fabricius were sustained development and increases. In the embryonic period, the thymus indexes, spleen indexes and the bursa of Fabricius indexes of both the Jianchang duck and meat duck stayed in a low level, which were significantly lower than those is other times without obvious change. After hatching out, all indexs were increased:index of spleen and bursa of Fabricius began to rise at week1, but thymus index began to rise at week2. All of the three indexed reached the first peak at week2, in particular thymus index was above4.5. After week2, indexes began to decline in different way and then rise again.Then two varieties revealed different growth patterns, and they reached the second peak at wee8, when the thymus index and spleen index of Jianchang duck were dominant. Throughout the entire process of duck growth up, the spleen of meat duck developed quickly, but the thymus and bursa of Fabricius holds the development advantages in Jianchang duck.2. The correlation coefficients of Jianchang duck body weight and thymus index, spleen index, bursal of Fabricius index were0.738,0.096and-0.282, respectively, which were0.631,0.140and-0.461respectively in meat duck. The correlation coefficients of The organ indexes between embryonic period and after hatching out at different time stages of Jianchang duck were very stable, which maintained around0.7except week8. But the correlation coefficients in meat duck were abnormal without regularity.3. From week2to week8, there was an common appearance in the lymphocyte count increased of all organs in both Jianchang duck and meat duck, and in which increase of the thymus and bursa of Fabricius were more obvious, and the bladder structure of bursa of Fabricius cell was also more complete. There were no significant differences between the tissue structures of the two breeds at week2. But in week8, the number of lymphocytes in Jianchang duck thymus and bursa of Fabricius was much more than that in meat duck, while the number of splenic lymphocytes was much more in meat duck.4. Week2,the INF-y content in both meat duck and Jianchang duck serum were high, after which they decreased slowly. To week10, INF-y levels significantly increased, and then began to decline. In the whole process, Jianchang duck revealed some advantages over meat duck, which were slightly higher than that of meat duck except week2. The contents of serum immunoglobulinin in Jianchang duck has increased slowly during the period of week2to8,and then declined slowly too, While which was relatively low and fluctuated in meat duck during the period.5. Week2, the expression of IL-2in thymus and the expression of TLR4in spleen in Jianchang duck were higher than which in meat duck. And in week8, the expression of TLR4in the spleen in meat duck was higher than which in Jianchang duck, and the expression of IL-2in the thymus in meat duck was higher too. But the IgM’s expression in Jianchang duck still got more advantages. So, the development levels of the thymus and bursa of Fabricius of Jianchang duck were higher than meat duck, while development level of spleen was lower than meat duck. Secondly, and different immune organ development status determined the differences of immune function of Jianchang duck and meat duck.