North Central Research Extension Center


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Bull Fertility Testing

It‘s recommended that breeding bulls undergo a breeding exam/fertility test annually.  Most bulBull Fertility Testingl sellers have their offerings tested or guarantee they will be satisfactory breeders and pass a test performed latter.  Bulls being sold at less than a year of age and have been developed under a heavy feeding program, may not be quite mature enough or conditioned properly to get a fair test before the selling.  An exam only identifies reproductive soundness on the date of the test.  Since a multitude of things may occur in the interim of a test and when turned out to breeding, a test closer to breeding may be preferred.

North Dakota veterinarians participated in project last spring to summarize incidence and reasons for failure of bulls to pass breeding soundness exams.  Out of almost 6,000 bulls tested 660 failed for an average overall failure rate of 11%.   Within yearling age bulls, the failure rate was 17%, mostly for reasons associated with semen morphology.  Failure rate for rested bulls remained quite high.  DNA testing  of calves from herds running multi sire breeding pastures for sire identification is also interesting in regards to sire fertility and dominance.  We find there are sire(s) often producing no or few progeny within breeding groups.

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