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Premier Sires
Lethal genes have been around for a long time, and will continue to occur in our national herd. It ’s not too long ago that we had never heard of BLAD or CVM, and new genes (good and bad) are being discovered with increasing frequency.
DataMATE has the potential to allow the industry as a whole to manage single genes, both lethal and beneficial. If DataMATE had been around in the days of BLAD, it would have been a great help. Already, it is proving a valuable tool for managing the incidence of CVM in the national dairy herd.
But DataMATE is just one of the methods Livestock Improvement uses to ensure the New Zealand dairy industry is well protected against lethal genes.
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Consider the management of CVM as an example case:
CVM (Complex Vertebral Malformation) is a recessive gene that occurs in some Holstein-Friesians descended from Carlin-M Ivanhoe Bell, an overseas bull. A mating between two CVM carriers has a 25% chance of producing progeny that are either aborted before term or are born malformed. The impact of CVM can be managed by avoiding the mating of carrier cows with carrier bulls.
The CVM gene was first identified in October 2000, at which point LIC was committed to the bulls already coming through the Sire Progeny Test. But we took immediate action.
- All Premier Sires bulls have been DNA tested so we know which bulls are CVM carriers.
- From 2002 onwards, bulls entering SPS have been DNA tested for CVM, and a CVM+ bull has to rank very high for other traits to be considered for progeny testing. (Only 4-8 out of 150 Holstein-Friesian bulls are now CVM+, so from 2006 onwards there will be a very low chance of a CVM carrier bull being selected for Premier Sires. )
- In the meantime, only highly ranked CVM+bulls that make a significant contribution to team BW and TOP that more than compensates for their CVM status have been (or will be)selected for use in Premier Sires.
We do not know the CVM status of cows to be inseminated with Premier Sires because the cows have not had the required DNA test. However, by knowing each cow ’s ancestry we estimate that we can provide protection for the great majority of matings by bulls likely to lead to double copy CVM calves.
- DataMATE can identify all cows that we estimate to have a 15%or greater chance of carrying a single copy of the CVM gene.
- DataMATE gives warning of a potential double-copy CVM mating, so the simple action of using the next BW bull of the same breed in the semen issue will prevent potential problems. (LIC ensures that there is no more than one CVM+bull per Long-Last Liquid issue. )
- Because they do not have the benefit of DataMATE, DIY Premier Sires farmers are provided with a complimentary Inbreeding and Gene List which will help them manage inbreeding and identify cows that should not be mated to CVM+bulls.
Livestock Improvement’s ability to manage CVM matings, and other matings involving other as-yet undiscovered genes, is extremely positive. It means that bulls with otherwise highly desirable traits are not wasted to the dairy industry. It ’s also important to realise that LIC has the ability to take – and indeed, , does take – corresponding positive actions to maximise the usage of bulls carrying favourable genes. In fact, this is the essence of Premier Sires.
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