Culling all cows that do not give birth to a healthy calf prior to the next breeding season greatly reduces the chance of an infected cow spreading Trich to uninfected bulls. When a cow is bred by a bull infected with Trich the resulting infection usually causes abortion 15 to 80 days into the pregnancy. A small percentage of infected cows will abort later.  After aborting, infected cows may begin to cycle again before they have cleared the infection. Bulls that breed these cows may become infected with Trich. 

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