Effects Of Colistin Sulfate On The Growth And Development Of Immune Organ And Erythrocyte Immunity Function In Chickens

Objective: To study the effect of dietary colistin sulfate on the weight, the index and the tissue structure of immune organs, and erythrocyte immunity function. It would provide a theoretical basis to add colistin sulfate reasonably in poultry production. Methods: 160 one-day-old Avian chickens were randomly divided into five groups, and fed on diets as follow: basic diet (Colistin sulfate 0mg/kg, controlâ… ) and different dose diets (Colistin sulfate 20 mg/kgâ…¡, 40mg/kgâ…¢, 60mg/kgâ…£, 80mg/kgâ…¤) respectively for six weeks. The thymus, bursa of fabricius and spleen were weighed and fixed in Bouin liquid. Afterwards the tissues were made into paraffin section and stained with HE, then observed with microscope and photographed. The erythrocyte C₃bR and IC ratios were tested respectively each week. The thymus, bursa of fabricius and spleen were made into electron microscopic section in groupâ… andâ…¤at 42 days age. Results: The absolute weights and the indices of immune organs in groupâ…¢,â…£,â…¤dropped obviously compared with those of groupâ… (P＜0.05 or P＜0.01). Microscopically, the widths of thymic in groupâ…¢,â…£,â…¤decreased greatly compared with those of groupâ… in 28～42 days age (P＜0.05 or P＜0.01). The areas of lymph follicle, lymph cortex and lymph medullary in bursa of fabricius, the areas of splenic corpuscle and periarterial lymphatic sheath in spleen in groupâ…¤decreased remarkably compared with those of groupâ… in 21～42 days age(P＜0.05 or P＜0.01), so did those of groupâ…¢andâ…£in 28～42 days age (P＜0.05 or P＜0.01). Ultrastructurally, the nuclear membranes of lymphocyte and reticular cell were broken; the rough-surfaced endoplasmic of lymphocyte, reticular cell and plasma cell were swelling in immune organs; the crista of mitochondrion was broken in plasma cell of spleen. Meanwhile, the erythrocyte C₃bR and IC ratios decreased markedly as the chicken grew and colistin sulfate dosage increased, especially in 60mg/kg and 80mg/kg groups when compared with those of control group. Conclusions: This study indicates that the absolute weights and indices of immune organs and the erythrocyte immunity functions were decreased in various degrees by different doses of colistin sulfate, which shows both time and dose dependence. Lymphocyte and reticular cell of immune organ were broken in the groupâ…¤. It's suggested that the dose of colistin sulfate should be lower than 40mg/kg in the chicken feeds, and 60, 80mg/kg colistin sulfate should be forbidden in the chicken feeds.