不同日龄鸡对毒害艾美耳球虫的易感性研究

The susceptibility of chickens at different ages to Eimeria necatrix

为了评价不同日龄鸡对毒害艾美耳球虫的易感性,选择18、40、70日龄黄羽肉鸡各30只,每个日龄均分3组,即不感染对照组、感染Ⅰ组和感染Ⅱ组,其中感染Ⅰ组和Ⅱ组分别经嗉囊接种毒害艾美耳球虫孢子化卵囊3×104和6×104个/只,统计各组的血便数、平均增重、死亡率、病变记分等指标。结果:18、40、70日龄鸡感染卵囊3×104个/只时,死亡率分别为40%、50%和30%;感染6×104个卵囊/只时,死亡率分别为90%、60%和70%。死亡发生的高峰均在感染后第6天。各感染组的平均增重均显著小于各自的不感染对照组(P<0.05)。总体来看,低剂量组的平均病变记分要低于高剂量组,在18日龄鸡中差异显著(P<0.05),但在40日龄和70日龄鸡中差异不显著(P>0.05)。结果表明:不同日龄的鸡对毒害艾美耳球虫感染均具有很高的易感性,在高剂量时日龄大的鸡可能引起的死亡率有所降低,但对增重率和病变损害程度的影响并未减少。

In order to evaluate the susceptibility of chickens of different ages to Eimeria necatrix, yellow-feathered broilers at 18, 40, 70 days old were infected with 3 ×10^4 or 6 ×10^4 sporulated oocysts, respectively. The susceptibility was determined based on the number of bloody stool, average weight gain, mortality and lesion score. The results showed that the mortalities in 18, 40, 70-day-old chickens infected with 3x104 ooeysts were 40% , 50% and 30% , respectively, and those infected with 6×10^4 oocysts were 90% , 60% and 70% , respectively. Compared with the uninfected group, the average weight gain in the infected groups were reduced significantly （ P〈0.05 ）. The lesion scores of the groups infected with 3×10^4 oocysts were generally lower than those of the groups with 6×10^4 oocysts, but there was no significant difference （P〉0. 05 ） except among groups of 18-day-old chickens （P〈0.05）. It is concluded that the susceptibility of chickens to E. necatrix was almost equal among different ages, but the mortalities of young birds tended to be higher when infected with high dose of oocysts.