鸡胚接种柔嫩艾美耳球虫和堆形艾美耳球虫活卵囊的免疫保护试验

给18日龄鸡胚接种一定剂量的柔嫩艾美耳球虫(Eim eria tenella)和/或堆形艾美耳球虫(E.acervulina)孢子化卵囊,出雏后在无球虫环境中笼养,1~10日龄每天收集各组粪便样本,计数克粪便卵囊数(OPG),并于14日龄时以大剂量同源孢子化卵囊攻虫,以相对增重率(RWG)、饲料转化率(FCR)、相对卵囊产量(ROP)评价免疫保护效果。结果显示,以E.tenella或E.acervulina卵囊免疫18日龄鸡胚,其卵囊排出的潜隐期及达到峰值的时间与1日龄雏鸡接种组相一致,有相似的排卵囊曲线,提示其诱导免疫的建立是在出雏后开始建立的。攻虫后各免疫组的RWG由攻虫对照组的31.9%~51.7%提高到了76.5%~83.6%,RCR由攻虫对照组的4.11~4.89改善为2.72~2.96,ROP降至4.7%~23.5%。结果表明以一定剂量E.tenella和E.acervulina卵囊单独或混合经羊膜腔免疫18日龄鸡胚都可以建立起针对出雏后14日龄同源攻虫的良好免疫保护力。比较混合免疫E.tenella和E.acervulina卵囊组与单一接种E.tenella或E.acervulina卵囊组的免疫效果发现,混合免疫组的各项指标均稍优于后者。

Efficacy of immunoprotection against coccidiosis by in ovo vaccination with Eimeria tenella and E.acervulina oocysts

Efficacy of immunoprotection against coccidiosis was investigated by in ovo inoculation with the oocysts of Eimeria tenella and/or E.acervulina.The fertiled Lingnanhuang broiler chicken eggs were injected through amniotic sac on 18 d of incubation with the oocysts of E.tenella and / or E.acervulina.The hatched chickens were reared in wire-cages and oocysts outputs were detected using OPG(oocysts per gram of feces) during day 3~10 post-hatched.The vaccinated chickens were challenged with a high dose of the homologous oocysts of E.tenella and / or E.acervulina at 14 d posthatch,and the immunity efficacy against homologous Eimeria oocyst challenge was evaluated by relative weight gain(RWG),feed conversion rate(RCR) and relative oocysts production(ROP).The chickens inoculated in ovo with oocysts had significantly reduced oocysts output(ROPs were in range of 4.7%~23.5%), meanwhile,with significant increase in RWG(reached 76.5%~83.6%) and better FCR(ranged in from 2.72 to 2.96) compared to the nonimmunized counterparts.The results suggested the feasibility of immunizing chicken by in ovo injection with two different Eimeria species of oocysts.