The ETB-2 was given by drenching after being implanted 24 hours, while control groups were given saline water.

• 采用接种后24小时灌胃给药，ETB-2A、ETB-2B、ETB-2C分别为39/kg/d、4.；58/kg/d、6g/kg/d，对照组则以生理盐水灌胃。