Farm Ireland

Saturday 23 September 2017

Genetics is future of sheep breeding

Sheep Value Index set to help farmers increase profitability

Nirn McHugh

The importance of genetic improvement in animal production has long been established with approximately half of the gains that can be achieved in animal performance attributed to genetics.

Genetic improvement is permanent and cumulative so breeding decisions that you make today will impact future generations of animals in your flock. For example, if you were to use animals with "good" genes then the effects of these "good" genes will remain in the flock; on the downside the reverse is also true.

The contribution of genetics to profitable farming can be witnessed first hand in both the dairy and beef sectors in Ireland. Until recently the sheep industry had not witnessed these expected gains; however, with the establishment of Sheep Ireland in 2008, a dynamic genetic improvement breeding programme has been put in place. The ultimate goal is to be able to provide commercial farmers with estimations of the genetic merit of animals, which are comparable across breed, like that which has been achieved in dairy and beef cattle in Ireland.

Sheep Ireland

The aim of the national sheep breeding programme is to produce a low cost, easy care sheep with good maternal characteristics, and one that will produce a quality lamb with high growth rates that will reach slaughter at a young age.

Data is recorded on the traits of interest across a range of commercial and pedigree flocks and the weighting of each trait is dependent upon its economic importance to the average farm. All economically important traits are then summed into three sub-indexes which in turn are summed together into an overall breeding index. This index, called the Sheep Value Index, is a tool to help farmers in making more informed breeding decisions that can increase flock profitability.

The Sheep Value Index is a measure of the genetic ability of the animal's progeny to generate profit at farm level. The Sheep Value Index is further differentiated into four goal trait groups, or sub-indexes, each weighted by their relative economic importance:

•Production Sub-index -- This ranks animals based on their ability to produce good terminal progeny. This takes into account the progeny's carcass characteristics and days to slaughter (growth rate). Carcass characteristics are predicted from ultrasound information and live-weights.

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•Maternal Sub-index -- This ranks animals on the expected performance of their daughters and takes into account the daughter's mothering ability (milk), the difficulty of lambing, and the efficiency at which their progeny are finished.

•Lambing Sub-index -- This ranks animals for lambing traits and takes into account the lambing difficulty and survivability of the animal's lambs.

•Health Sub-index -- Not yet available but will be available once sufficient data is generated and will ideally contain traits such as: footrot, dag score, and faecal egg count (a trait used to measure parasite resistance), amongst others.

How to use the index

•Interpreting the €uro-value:

For each of the sub-indexes and the overall Sheep Value a corresponding €uro-value is published. The €uro-value is the predicted extra profit that will be generated for the animal's progeny compared to an 'average' lamb and is scored on a scale of 1 to 5 and compares all animals within each breed; a one star indicates that the animal lies within the bottom 20pc of ranked animals for the given trait and a five star corresponds to the top 20pc of animals For example a ram with an €uro value of €0.15 is expected on average to produce progeny that will generate €0.15 more profit compared to a ram with a €uro value of €0.

•Understanding the accuracy -- Another key component to the indexes are the accuracies that are published for every €uro-value. The accuracy explains the "confidence level" that is associated with each €uro-value.

The higher the accuracy of the given trait, the greater the information that is known about the animal and the greater the confidence we have that their published index value reflects the true genetic merit of an animal. Accuracy values must be viewed alongside the €uro values.

The lower the accuracy, the greater the extent to which the €uro value may move as more information is accumulated. One can get around low accuracies by using a team of rams, thereby spreading the risk.

•Selecting the most suitable animal -- Each farmer must next determine the most suitable animal for their production system. The next question is how to achieve that ideal animal.

For example, if farmers are interested in finishing all their lambs then they should pay particular attention to the production sub-index of the ram. On the other hand, if a farmer is looking to breed their own replacements then they should examine the maternal sub-index carefully, in combination with the production index.

Future research priorities

Although considerable progress has been achieved in sheep genetics in Ireland, ongoing research and explanation of how to exploit the research is necessary to further demonstrate the importance of sound breeding decisions on profitability.

Access to large quantities of accurately recorded data is one of the main obstacles to accurate genetic evaluations in Ireland. Traits such as health (footrot, susceptibility to parasites and fly strike), meat quality, lamb vigour and feed intake are economically important but in order to include such traits in genetic evaluations, tools must be developed to facilitate the accurate recording of the pertinent traits.

Additionally, research will be undertaken to validate the current Sheep Value Index under contrasting production systems. Such an experiment would involve groups of animals segregated on genetic merit (ie, high and low) and their performance and differences on profit compared to expectation based on predicted genetic merit. Genomic selection can also be of great benefit to the sheep sector, but the national breeding programs and validation studies must be prioritised initially.

Finally, genetic evaluations are a good tool for sheep farmers and enable them to make more informed breeding decisions and potentially increase profitability at farm level. However, before the Sheep Value Index is widely used within the industry farmers need to:

•Understand how to use the index;

•Have a good knowledge of the science behind the index;

•See the benefits of the index at farm level.

This process may take a number of years but with the correct breeding programme in place the results can be hugely successful.

Nóirín McHugh is a Teagasc specialist at Moorepark, Fermoy, Co Cork

Indo Farming