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

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

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)在肉仔鸡日粮中添加 150mg/kgCTC ,可以显著地提高肉仔鸡的增重速率和饲料转化效率 (P <0 0 1) ,改善率分别为 6 4 3%和 5 6 6 % ;B组与对照组相比 ,差异不显著。 (2 )随着日粮中CTC添加量的增加 ,肉仔鸡胸腺、脾脏和法氏囊的萎缩程度逐渐增加。当CTC添加量达到 150mg/kg时 ,无论前期还是后期肉仔鸡胸腺、脾脏和法氏囊的重量都明显低于对照组 (P <0 0 5) ;添加 50mg/kg的CTC对免疫器官重量也有一定程度降低。随着饲用时间的持续 ,CTC对免疫器官生长的抑制率明显提高。 (3)C组鸡外周血T 淋巴细胞对丝裂原ConA或PHA的反应性以及B 淋巴细胞对丝裂原LPS的反应性明显低于对照组 (P <0 0 5)。添加 50mg/kgCTC也会抑制T或B细胞的增殖。 (4 )随培养介质中CTC浓度的逐渐增加 ,PHA对T淋巴细胞刺激的反应性逐渐降低 ,呈明显的负相关 (R =0 82 95)。

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).