Joint Media statement from LIC and CRV Ambreed
Use of DNA sequence technology by farmer cooperative Livestock Improvement (LIC) has led to the discovery of a recessive small calf gene - opening the door to managing Small Calf Syndrome out of the dairy industry.
David Hemara, Acting CEO of LIC, said “This is an important discovery. Identifying the gene means we can start managing a problem which has existed on farms for decades.”
The Small Calf Syndrome affects predominantly Holstein Friesian and a lesser number of crossbred animals. Incidence of the Syndrome has been assessed to be around one to two affected calves in the average 400 cow New Zealand herd per year.
David Hemara said that LIC’s large genetics database and ongoing research programme enabled the Cooperative to “go back 30 years screening the DNA of our bulls, and beyond that through pedigree records. That research suggests the genetic variation existed in the early 1960s and possibly before then. We can’t be sure of when or where it started.”
David Hemara said LIC understands that the gene’s discovery will be of interest to dairy farmers with Holstein Friesian or crossbred animals.
“Our programme of gene discovery and DNA sequencing is improving our ability to isolate negative genes. This is a good thing for the dairy industry.”
Eradicating the genetic variation from the national herd is a priority for genetics companies and CRV Ambreed CEO, Angus Haslett, emphasised the discovery’s importance “to all New Zealand breeding companies and farmers.
“Over the years a number of genetic variations have been discovered and managed out of the industry and this will be no different. CRV Ambreed will work with LIC to manage this genetic variation so its impact is minimised on New Zealand farms in the future.”
David Hemara said “This is the latest in a range of genetic variations which have been discovered, and largely eliminated, over the years. Diseases like CVM and BLAD used to be present in New Zealand herds but their incidence has been reduced thanks to their discovery and managed removal from the national herd.
INFORMATION PACK (1 May 2013) - SMALL CALF SYNDROME
New Zealand dairy farms commonly lose between two and four percent of calves each year for a variety of reasons.
Over the last 10 to 15 years LIC has received a number of calls (up to 20) from farmers about small calves being born. We undertook three farmer surveys over the last six years to establish how widespread the condition was so we could concentrate our research to establish whether there was a genetic link to the condition. The resulting survey data suggested the condition might have a genetic basis.
LIC has only now been able to confirm this genetic link through its ongoing investment in DNA sequencing technology.
DNA sequence technology allows the entire DNA profile of an animal to be mapped out. This technology has allowed LIC scientists to map and compare the DNA of many different AI sires and to identify specific differences in their DNA.
Comparing the DNA sequence of a large number of sires has enabled LIC to identify a specific segment of DNA (one piece out of 3.2 billion) which is linked to the Small Calf Syndrome. Its presence has also been confirmed in a number of AI sires in New Zealand.
The mode of inheritance for this genetic variation is recessive because an animal needs two copies of the variation before it is affected ie both parents. Where both parents carry the recessive variation there is a one in four chance that the progeny will be affected.
It is impossible to predict where and when this genetic variation first occurred. LIC has gone back 30 years conducting DNA screening on all its bulls and beyond that through pedigree records which suggest the gene variation existed in the 1960s and possibly earlier.
Why has LIC been able to find this genetic variation now when it’s been in the population for decades?
LIC invests millions of dollars every year in genetics research. For the first time we are now able to map the entire genome of dairy animals and compare those DNA sequences to other animals in the population to identify key genetic differences. LIC has recently developed one of the largest dairy sire DNA sequence sets in the world.
Our goal is to continue to research these DNA sequences to identify both positive and negative variations. Identifying positive genetic variations enables us to add this knowledge to our genomic selection tools which improves our breeding programmes and leads to better cows. Identifying negative genetic variations enables them to be managed down in the population.
What do calves with Small Calf Syndrome look like?
They are generally healthy calves but significantly smaller at birth or as they grow out.
What is the frequency of the Small Calf Syndrome in the average New Zealand Holstein Friesian herd?
The average herd of 400 cows could expect to have 60 cows which are carriers. If this herd was mated to a cross-section of Holstein Friesian bulls in New Zealand LIC expects one to two calves would result.
Putting this into perspective, since the 1960s a quarter of one percent (0.25%) of calves bred from Holstein Friesian or crossbred type animals each season are likely to have been affected by the Small Calf Syndrome.
Are carrier cows affected in any way?
Dairy animals which carry one copy of this gene are known as carriers. Both cows and bulls can be carriers. They are healthy and not affected by the genetic variation.
Are all small calves caused by this Syndrome?
No. A proportion of small calves will be small because of this genetic variation but there are a range of other factors which can affect the size of calves eg BVD, scours, disease, etc.
What can farmers do to avoid breeding calves with Small Calf Syndrome?
The gene’s discovery has led to the development of a DNA screening test which LIC is applying to all its bulls. The test will also be made available to other genetics companies so they, in turn, can screen their bulls.
LIC AB Technicians use DataMate, a handheld computer which contains each farm’s herd records and into which potential matings are entered giving an alert for a number of factors (like inbreeding etc).
Where it is possible that a cow is a carrier because of her ancestry, the use of DataMate will minimise carrier to carrier matings reducing the incidence of calves with the Small Calf Syndrome. This will mean the present incidence of one to two affected calves per average Holstein Friesian herd will reduce to almost zero over time.
LIC will ensure that bulls which enter the LIC Sire Proving Scheme in future do not carry this genetic variation.
The good news is that the discovery of the genetic variation means that, in time, the Small Calf Syndrome will be managed out of the national herd.
What high use LIC bulls are carriers of the genetic variation?
The following high use LIC bulls have been identified as carriers of the genetic variation:
Brightwater DC Carl
Glenmead RE Holiday-ET
Hazael Eminence Dano
Kingsmill RE Lancer
LIC will be making the screening test available to all genetics companies with the expectation that they will test their AI sires and publish the results.
How many LIC bulls have been carriers of the gene variation?
We estimate that, over 30 years, around 350 LIC bulls have carried this genetic variation. Given that LIC is the only genetics company to have applied the screening test to its bulls, we are unaware of the numbers of bulls used by other genetics companies.
Will LIC remove all high use sires from its bull teams?
No. All LIC bulls are being screened for the genetic variation and any which are carriers will be clearly identified on DataMate ensuring that an alert is given to minimise the chances of the mating of a carrier bull to a carrier cow.
What is the difference between a recessive genetic variation and a dominant one?
The Small Calf Syndrome is a recessive genetic variation which means both parents must carry a copy of the genetic variation in order for the progeny to have a chance of being affected (one in four chance). A dominant defect is where progeny only need to carry one copy of the gene to be affected.
Will more negative genetic variations be discovered?
Yes and it is vitally important that LIC continues this research. The most recent human research in this area has confirmed that most humans carry 40-110 variations with negative effects. LIC expects to discover more genetic variations in dairy animals and that bovines will have a similar number of these negative gene variations. LIC is committed to researching and discovering those genetic variations because discovery provides the ability to manage them out of the national herd.
Is this the first recessive gene discovered in dairy animals?
No. There have been numerous examples of recessive undesirable genes discovered in dairy animals around the world eg CVM, BLAD, DUMPS, Brachyspina, Factor XI and Mulefoot. The discovery of each genetic variation has led to the introduction of managed programmes which have significantly reduced them in dairy populations both internationally and in New Zealand.
What should farmers be doing this calving season?
Our advice to farmers is that calving in 2013 should be ‘business as usual’ and they should make their normal assessment as to which calves are suitable to rear. As always calvings should be recorded. DataMate can also be used during the mating season to reduce the incidence of this gene variation going forward