Genomics sets new standard for livestock breeding

“DNA technology” is set to change the way some semen companies select bulls and is claimed to be the biggest development since frozen semen.

And as early as next spring farmers could see Genomic Estimated Breeding Values (GEBVs) replacing EBVs, increasing reliability from the genomic data, with EBVs being officially replaced in Canada and the USA in early 2009.

Semex Alliances senior geneticist Jacques Chenais reckons the change will enable producers to make more rapid genetic progress, particularly for low heritability traits like fertility, longevity and eventually health traits, ultimately increasing profitability.

So how does genomic selection work?

Genomic Selection involves analysis of DNA to predict the performance of a bull’s daughters rather than waiting years for them to come into milk. Young bulls can be pre-selected depending on their DNA profile before they are progeny-tested allowing a larger number young bulls from across more families to be screened as candidates, says Dr Chenais.

Currently Semex who are taking part in the North American Genomic Selection Project, has identified 58,000 markers to help predict the genetic merit of an animal allowing them to select on that basis. Dr Chenais says more than 5000 proven bulls in the project have been genotyped to see whether their genomic evaluations predict their proof.

“The genomic EBV combines the marker effects identified and parent averages, making GEBVs more accurate. But GEBVs are not as accurate as bull proofs,” he adds.

Understandably producers may already be questioning the accuracy of genomic selection as New Zealand breeding company LIC recently withdrew some of its genomically-tested bull teams due to a slide in their breeding worth evaluations.

“However, although this is a new technology and there are bound to be some surprises, the North American project has used more than 12,000 Holstein bulls compared to a significantly smaller number used by LIC.”

Practical use of genomics

“Using genomics in a herd is simpler than people may think. GEBVs look like EBVs, only more accurate, and should be used in the same way. They will benefit producers using young sires in their breeding programme as their chances of becoming elite will be greater,” he says.

Holstein Canada’s Glenn Cherry also reckons genomics will set the course for the future, with plans in place to develop a national DNA eartag collection system and DNA bank.

“A new Radio Frequency Identification Tag (RFID) which, takes a small patch of skin from the ear when inserted can be sent to a central DNA bank. This could help perform a low cost, basic genotype on a large number of registered animals,” he says.