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The ICBF has launched two new genetic evaluations for health traits – bovine tuberculosis (TB) and liver fluke resistance.
Genetic resistance to TB and liver fluke have been published for beef and dairy AI bulls that are either genotyped or have =20 progeny records in infected herds, the ICBF said.
Unlike other health traits which are included in the EBI or €uro-Star indices, genetic resistance to TB and liver fluke have been published as two stand-alone traits.
Incorporation
Over-time, the ICBF said that both traits will be incorporated into the EBI and €uro-Star indices and will be available for all animals.
Even though most cattle in a herd are managed as a uniform group, the ICBF said that there are differences in the genetic merit of cattle for resistance to TB and liver fluke infection, which translates to differences in the on-farm prevalence of TB and liver fluke infection.
Breeding values
Lower breeding values for resistance to TB and liver fluke are more desirable, according to the ICBF, meaning that fewer progeny are expected to become infected with a TB or liver fluke infection during their lifetime.
For each one percentage unit increase, 1% more progeny are expected to become infected.
Giving an example, the ICBF said that if a bull has a breeding value of 2% for TB resistance, on average 2% of his progeny are expected to be TB reactors in their lifetime.
Breeding values typically range from 0% to 20% for TB resistance and from 20% to 40% for liver fluke resistance.
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