Comparative histological study of lymphatic tissues of native laying hens with increasing age to evaluate the immune response

Today, due to population growth and the fact that white meat and eggs are cheap and healthy, the industry for the production of these products is expanding. In the laying and broiler industry, the study of the immune system is considered to assess the body's readiness to fight diseases. In this study, fourteen native laying hens, seven 5-week-olds and, seven 50-week-olds were evaluated to assess the immune system. At the end of the course, after blood sampling, macro examination of thymic lymph nodes, bursa of Fabricius, and spleen were performed. Then the parameters of blood, lymphatic organ weight relative to chicken weight, measurement of lymph follicle diameter, number of follicles were evaluated. The most abundant cells in birds were red blood cells. Measuring the length and width of a blood cell was no different from its standard. The lymphatic organs of the bursa of Fabricius, thymus, and spleen were histologically devoid of any lesions. The correlation coefficient between the live weight of chickens and the weight of lymphatic organs did not interfere between any of the groups. The parameters studied can be an indicator of the bird's health, indicating the potential strength of the immune response to common infections on the farm or on the open environment of birds.