鸡巨型艾美耳球虫早熟株免疫效果试验

Experimental study on the immune effect of a precocious line of Eimeria maxima

为确定使雏鸡获得良好免疫效果的最小巨型艾美耳球虫(E.maxima)早熟株接种量,分别于4日龄对免疫攻毒组以不同剂量进行首免,11日龄以首免2倍剂量对二次免疫攻毒组鸡进行二免。一次或二次免疫后7 d或10 d用同源亲本株进行攻毒,检测免疫攻毒鸡相对增重率、卵囊减少率、病变记分减少率(RLS)和抗球虫指数(ACI)。结果显示,一次免疫剂量≥400个孢子化卵囊/只或两次免疫的一免剂量和二免剂量≥100个孢子化卵囊/只和200个孢子化卵囊/只时,各免疫攻毒鸡的相对增重率≥85%,RLS≥70%,卵囊减少率≥75%,相对保护率≥90%,ACI≥170,均达到良好免疫效果。故将E.maxima早熟株的一次免疫最小免疫剂量定为400个孢子化卵囊/只,两次免疫最小免疫剂量定为一免100个孢子化卵囊/只和二免200个孢子化卵囊/只。

To determine the minimum inoculation dose of a precocious line of E.maxima in chickens,different doses of sporulated oocysts of the precocious line were orally administered to 4-day-old chickens the immunization groups.At the age of 11 days,the chickens in the second immunization group were immunized again with the double dose of the primary immunization.Chickens after one immunization for 7 days or twice for 10 days were challenged with sporulated oocysts of the parent strain,respectively.The relative weight gain rate,reduction of oocyst ratios,reducing rate of intestinal lesion scores and anticoccidial indexer were used to evaluate the efficacy.The results showed that the relative weight gain rate of chickens in the immunization groups was more than 85%,RLS was over 70%,the oocyst reduction rate was over 75%,the relative protection rate was more than 90%,and ACI was over 170,Once-immunization dose was more than or equal to 400 or twice-immunization dose was more than or equal to 100/200 sporulated oocysts of the precocious line for a chicken,which met the criteria and achieved a good immunogenicity.For once-immunization groups,a dose of 400 oocysts/feather was the minimum immunizing dose.And for twice-immunization groups,a dose of 100 oocysts/feather in the first immuization and a dose of 200 oocysts/feather in the second immunization were the minimum immunizing doses.