饲用金霉素对肉仔鸡免疫系统生长发育及免疫反应的研究

试验用１日龄ＡＡ商品代肉用公雏５４０只，随机分成３组，每组１８０只，分成１２个重复（１５只／重复），其中６个重复用作生产性能测定，另６个重复用于测定免疫学指标。在日粮中分别添加０（Ａ组）、５０（Ｂ组）、１５０ｍｇ／ｋｇ（Ｃ组）的金霉素（Ｃｈｌｏｒｔｅｔｒａｃｙｃｌｉｎｅ，ＣＴＣ）。试验表明：（１）在肉久日粮中添加１５０ｍｇ／ｋｇ ＣＴＣ，可以显著地提高肉伍鸡的增重速率和饲料转化效率（Ｐ〈０．０１）

EFFECTS OF CHLORTETRACYCLINE USED IN FEED ON THE DEVELOPMENT OF IMMUNE SYSTEM AND IMMUNE RESPONSE IN BROILERS

This research aimed at verify whether chlortetracycline(CTC) added to diet affects the immune response as well as the development of immune organs and performance in broilers.The basal diet composed of corn,soybean and so on.Three diets supplemented with CTC of 0(A group,control),50(B group) and 150 mg/kg feed(C group) were fed to three groups of 540 one day old Arbor Acres(AA) male broilers,the six ones of 12 replications of 15 broilers were used for determining the performance,and others for immune indexes.The results were as follows:(1) the diet with 150 mg CTC/kg increased significantly the body weight(BW) by 6 43% and the feed efficiency by 5 66% (P<0 01) compared with the control.B diet increased slightly the BW and feed efficiency (P>0 01).(2) The weights of immune organs to BW(as the index of immune organ)and the weights of thymus as well as spleen and the bursa of fabricius decreased significantly with the increasing of CTC in diet(P<0 01).The weights of all immune organs in broilers fed C diet with 150 mg CTC/kg by 21 or 49 days of age lowed significantly than those in control (P<0 05);B diet supplemented with 50 mg CTC/kg also decreased the weight of the immune organs(P>0 05).The inhibitory rate of the growth in immune organs raised significantly with the prolonging of the time for feeding CTC.(3) The proliferation of T lymphocytes induced by concanavalin A(Con A) or PHA and proliferation of B lymphocytes induced by LPS in peripheral blood were depressed obviously with CTC 150 mg/kg added in chick diet (P<0 05);The proliferation of T or B lymphocytes induced by different mitogens also depressed by diet containing 50 mg CTC/kg (P>0 05).(4) The higher the concentration of CTC in cultured medium,the lower the response of T lymphocytes to mitogen PHA.The inhibitory rate of CTC on proliferation in T cell was reversibly correlated with CTC content in diet (R=0 8295,P<0 05).