Dr Theirry Pabiou presented the relevant updates to the genetic evaluations at the Sheep Ireland Industry Meeting held on Monday 29th April 2019 in Tullamore Court Hotel, County Offaly.
The reason we update Genetic evaluations is so that we can produce more accurate genetic evaluations which will lead to:
- More accurate ram selection
- More profitable decisions
- Greater difference between 1 and 5 Star rams
- More confidence/emphasis placed on Star ratings
Adding Carcass Data to the Evaluation
For the first time, Carcass data will be used in the Irish Sheep genetic evaluations. The majority of the carcass data collected to date has been collected from the CPT flocks with over 6,000 records collected to date.
Previously Days to Slaughter was predicted based on the live weight of the animal at 100/150 days of age, however this did not fully take into account how the animal would kill out. The Figure below shows an extreme example of two CPT Charollais Sires. Both rams produced progeny of a similar liveweight at 150 days of age (37.5kg). Previously both these rams would have received a very similar Days to Slaughter value. However, in the new evaluation, using the carcass records of these animals we can see the progeny of the first sire hit the required carcass weight after 192 days, while the progeny from the second sire took 205 days, that’s an extra 13 days for animals that had the same live weight at 150 days.
This particular update will benefit the bloodlines that produce heavier carcase weight, and not just liveweight (even though these traits are strongly correlated). For flocks that have carcass data available on their performance recorded progeny, this can now be loaded via the Sheep Ireland website to help increase the accuracy of their EuroStars.
Genetic Parameters Update
The main outcome of this process is that the heritability’s of most of the traits recorded with Sheep Ireland have increased. This tells us 2 important messages, that quality of data being collected from pedigree flocks is of much better quality than it was in 2009, and the volume of data being collected on commercial animals has increased. Two very positive messages. These increases in heritability’s will also lead to higher accuracies in the genetic evaluations in 2019, which is another positive step forward.
Across-breed Evaluations
Until now, the Sheep Ireland genetic evaluations all happened within breed. This year for the first time the Sheep Ireland genetic evaluations will be run on an across-breed basis, allowing to compare rams from different breeds against each other using the Sheep Ireland Index’s and/or traits. This will also make the genetic evaluations for performance recording commercial (crossbreed) flocks more informative as they will now be able to compare all the ewes in the flock against each other.
This also helps to increase the accuracy of the evaluations as the amount of data available for each breeds comparison has increased.