New genomically enhanced reproduction breeding values for Merino sheep allow targeted selection for conception rate, litter size and ewe rearing ability

K Bunter1, A Swan1, D Brown1,2

1Animal Genetics and Breeding Unit, UNE; 2Meat and Livestock Australia

In 2019 Sheep Genetics introduced new breeding values for maternal breeds which separated net reproduction rate into its component traits: conception rate, litter size, and ewe rearing ability. This will allow breeders to specify breeding objectives more accurately (focussing more on lamb rearing relative to litter size for example). The new traits show considerable genetic variation and reliable predictive ability across the maternal breed population, even given low heritabilities. This paper will show results from the equivalent analysis for Merinos, which is still under development. Key differences between analyses for maternal breeds vs merinos will be highlighted.

Because we have only recently begun the work in Merinos a short extension may be necessary, if possible. I trust it is possible to upload an updated abstract at a later date.


Kim is a Principal Research Scientist with the Animal Genetics and Breeding Unit and has a keen interest in developing genetic evaluation systems for reproductive performance of females.

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