Breeding healthier sheep moves a step closer

Irish farmers may be able to breed healthier sheep in the coming years through the adaption of a new health sub-index.

The health sub-index, developed by Sheep Ireland, will play a small role in both the Terminal and Replacement indices – which are already in use on many Irish sheep farms.

Traits such as daginess (dag score) and lameness will be incorporated under the new sub-index. It is also hoped that other health traits, such as mastitis and parasite burdens, will be included in the future.

Huge differences in health traits

To develop the sub-index, Teagasc and Sheep Ireland examined data over 10,000 individual records on the most important health traits from pedigree animals.

These pedigree animals form the backbone of the star-rated rams that farmers select from at sales.

This work found some stark differences in the health traits, particularly lameness, between lambs born to different rams managed under the same conditions.

For example, in one flock where two rams produced lambs across multiple years, 91% of lambs born to one ram showed no signs of lameness, whereas for the other ram only 20% of lambs showed no signs of lameness.

Breeders can access the information

ICBF Geneticist, Thierry Pabiou, spoke at a recent Sheep Ireland industry meeting, where he said: “The health traits are in the 2017 genetic evaluation. Breeders can access this data through the Sheep Ireland website.”

Pabiou added that the introduction of the health sub-index will have no major effect on a ram’s rating, as it only accounts for a small proportion of the proof.

Despite the advancement, Sheep Ireland has no plans to display health sub-index data on the Sheep Ireland Euro-Star catalogue.

But, it may be displayed as an individual trait on LambPlus breeders’ online profiles in the future and, perhaps, on the Sheep Ireland ‘ram search’.

Initial accuracy will be very low given the amount of health data collected up to this point, but this will increase over time, it says.

This does not mean that health traits are not economically important as they most certainly are, it added, but higher impact traits such as ‘lamb survival’ and ‘number of lambs born’ will always have a more prominent role within the Euro-Star indexes.