An outline of sexed semen trials on diary cows

The View from Teagasc: Sexed semen is used on dairy cows to increase the number of dairy heifer calves born, and results in 90 per cent heifers and 10 per cent bull calves, compared to 50 per cent of each from conventional semen.

There is, however, a reduction in conception rates when using sexed semen. Previous data from the US and New Zealand suggest a 10-15 per cent drop in conception rate with frozen-thawed sexed semen compared with conventional, while using fresh sexed semen may only result in a 5 per cent drop in conception rate.

Teagasc, along with the Irish Cattle Breeding Federation and partner AI companies, ran a large-scale sexed semen field trial during spring 2013. The study was designed to verify the conception rates attainable when using sexed semen under Irish conditions, and enable Teagasc to provide recommendations for the future use of sexed semen on Irish dairy farms.

More than 15,000 inseminations were carried out on 392 farms as part of the trial, using conventional, fresh sexed and frozen-thawed sexed semen. A selection of 4,000 animals (cows and heifers) from the trial was scanned for pregnancy diagnosis earlier in the summer. These preliminary results indicate that frozen-thawed sexed semen has performed far better than expected, with a drop of only 7 per cent (49 per cent vs 42 per cent) in conception rates compared with conventional semen.

Conception rates using fresh sexed semen were disappointing though, at around 12-15 per cent lower than those achieved with conventional semen. The scanning also confirmed that 90% of cows pregnant to sexed semen inseminations are carrying a heifer calf. The excellent performance of the frozen-thawed sexed semen has beneficial implications for the potential future use of the technology in Irish dairy herds.

A more detailed analysis of the preliminary results will be presented at the National Dairy Conference next Tuesday and full results of the trial will be available in spring 2014 following calving.

By Ian Hutchinson, Teagasc, Moorepark Animal and Grassland Research and Innovation Centre

The 2013 Teagasc National Dairy Conferences will take place at Limerick Racecourse, Patrickswell, Co Limerick on Tuesday, November 12, and the Slieve Russell Hotel, Ballyconnell, Co Cavan on Wednesday, November 13. The theme for the conference is ‘Strategies for Sustainable Success’. The conference will outline the key strategic decisions required by farmers in the areas of grassland, breeding and business planning in order to successfully grow their dairy business and to harvest the potential.

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