Experimental concurrent infections with Ostertagia ostertagi and Cooperia oncophora in the calf.

An experiment was conducted to investigate the effects of experimental concurrent infection with Ostertagia ostertagia and Cooperia oncophora compared with the effects of monospecific infections with O ostertagi under conditions designed to mimic natural conditions on pasture during a grazing season. The present experiment was not able to demonstrate any significant effect of C oncophora on the course of an O ostertagi infection. Neither did C oncophora influence the build up of immunity to O ostertagi as demonstrated by post mortem worm count results from challenge infections with hypobiosis-prone larvae.