Comparison of Characteristics and Differences in Early Immune Organ Development in Different Strains of Tianfu Broiler

To effectively develop and utilize high-quality Tianfu broilers, this study evaluated the morphological and structural characteristics of the immune organs of such broilers with different strains (HS1 and HS2) at different developmental stages and analyzed the distribution of mast cells by toluidine blue staining. Moreover, the localization and expression of immunoglobulin, complement C3, C4 and CD3 in immune organs were also detected. The results showed that although there was no significant difference in the development of immune organs in the HS1 and HS2, the number of lymphatic follicles and capsule thickness in the spleen and bursa of Fabricius in HS1 were greater than those in HS2. Additionally, the number of mast cells in the spleen of HS1 was greater at Day 1 and Day 21 and was significantly higher than that of HS2 ( p <0.05); the number of mast cells in the bursa of Fabricius reached 9.17 on Day 7, which was significantly higher than that of HS2 ( p <0.05). Moreover, the serum IgA and IgM levels in HS1 were higher than those in HS2 on Day 14 and 21 ( p <0.05). In addition, the complement C3 content in HS1 was significantly or extremely significantly higher than that in HS2 on Days 1, 14 and 21 ( p <0.01, p <0.05), respectively, but significantly lower than in HS2 on Day 7 ( p <0.05). These results indicated that the disease resistance of the HS1 line was stronger than that of the HS2 line, which lays a foundation for future disease-resistance breeding of Tianfu broilers.