根据死亡和增重判断早熟株的致病性较亲本株大大降低，但其免疫原性也有一定程度的下降。

The precocious line was much less pathogenic than the parent strain judged by mortality and weight gains, but its immunogenicity was reduced to some degree.

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根据死亡和增重判断早熟株的致病性较亲本株大大降低，但其免疫原性也有一定程度的下降。

The precocious line was much less pathogenic than the parent strain judged by mortality and weight gains, but its immunogenicity was reduced to some degree.

youdao