Breakthrough in sexing semen
Over the past few weeks some special calves have been arriving on dairy farms. These are the first calves in the world born from AI straws which have been processed using new technology designed to deliver extra heifer calves.
The straws, collected from AI sires at the National Cattle Breeding Centre (NCBC) in Enfield, were the end product of a joint semen sex biasing project between NCBC and Arex Life Sciences based in Boston USA.
The collaborative project has been under way at laboratory level for some time and in December 2007 NCBC, through its partners Munster Cattle Breeding and Progressive Genetics, began the field trials of AI straws treated with this process.
About 1,400 inseminations with the processed straws from Holstein bulls were carried out, many of them on farms in Wexford and the midlands. The cows were chosen at random and fertility rate to the processed straws was normal.
Some 498 of the pregnant cows were scanned and this showed that the cows were carrying on average 57pc heifer calves and 43pc bulls. This was analysed as being highly statistically significant. There is a 95pc confidence that the true sex bias lies between 53pc and 62pc female. A check on the sex of all the calves born to the processed straws will be carried out over the next couple of months. The results are being submitted to Teagasc for their assessment.
Unlike other sexed semen products on the market internationally, the new NCBC/Arex process does not compromise semen fertility. The laboratory process is extremely gentle on the sperm and normal fertility is expected. However, the process does slow down the AI collection and freezing routine and NCBC has had to invest in extra lab equipment at Enfield.
The heifer bias semen has been branded Female Advantage. Female Advantage straws are already commercially available on a selection of the top EBI Holstein sires to DIY AI users through Munster Cattle Breeding and Progressive Genetics AI. The Female Advantage straws will sell to DIY farmers at a price premium of €6/straw. Farmers using the AI technician service should book in advance to ensure that the straws are supplied to the AI technician.
NCBC has the exclusive rights for the Female Advantage technology in Ireland and has the option also for the distribution rights in Northern Ireland and Britain.
Initially, only Holstein straws have been collected using the Female Advantage process. But already NCBC has had requests from suckler herdowners to apply the process on maternally proven beef bulls. Herdowners looking for suckler replacements would welcome Female Advantage semen. In particular, the process has been requested for Salers, Simmental and Limousin bulls.
The issue of getting excessive male calves has been a running sore among dairy farmers even though the national average from conventional semen works out at about 51pc male, 49pc female. The herdowners involved in the field trial have expressed great enthusiasm for the process and want to continue with Female Advantage products.
Existing approaches to sexing semen have been detrimental to the sperm and conception rates suffered, so much so that the use of sexed semen is mainly confined to maiden heifers.
For years, Irish farmers have waited for semen that delivers more heifers without affecting the fertility of the semen. Using the sex biased semen, dairy farmers can choose to continue to use dairy breeds and deliver extra replacement heifers for sale. Herdowners who have used dairy stock bulls in the past will now have an extra reason for switching to AI sires. Only top daughter and genomically proven dairy bulls are being used to process into Female Advantage product.
At a ratio of 57pc heifer and 43pc bull, calves actually deliver 37pc more heifer than bulls on the ground.
NCBC and partners continue to work to refine the process and hopefully increase the percentage heifers delivered by the Female Advantage semen.
- Bernard Eivers
Irish Independent
