At the last national sheep conference, Dr Noirin McHugh of Teagasc presented the latest validation results as part of her presentation on “Accelerating sheep genetic improvement in Ireland”. The data used in this validation was from 2013 to 2015 and based on 7,644 commercial lambs.

It is important to point out that the star ratings used in this validation were taken at mating time, therefore all the differences seen in Table 1 were predicted before the ewe was even put with the ram. These differences are at an individual trait level.

The one-star data represents the one-star rams that were mated with one-star ewes. The five-star data represents five-star rams mated with five-star ewes.

Lambs from five-star parents had 7% less lamb mortality and required less assistance at birth. Ewes with a five star rating for the replacement index were on average 4.18kg lighter (lighter ewes are easier to feed), but had a greater number of lambs born (+0.13 lambs) compared with the one-star ewes.

Progeny from five-star parents were also heavier at 40-day weighing and at weaning compared with progeny from one-star animals. While each of the differences across the traits may seem minor, when they are all combined, you have ewes that have more lambs, with less lambing difficulty, with heavier lambs at weaning, all from a slightly smaller ewe.

Read the full focus section on sheep breeding here