Genetic selection for reproductive performance

Reproductive traits have low heritability so genetic gains are slow, but cumulative. Australian Sheep Breeding Value (ASBV) traits available for reproduction include conception (CON), litter size (LS) and ewe rearing ability (ERA). This allows producers to focus on the traits that will lead to the most improvement in the flock if there is a specific aspect of reproduction that needs to be improved. The three reproduction ‘component traits’ (CON, LS and ERA) are also available as one combined trait called weaning rate (WR, formerly number of lambs weaned [NLW]), which is useful if producers are chasing an overall improvement in reproductive performance. 

Direct measures of reproductive performance are the most reliable and are the preferred way to make genetic improvement to reproduction, but they can be expensive and difficult to collect for some ram breeders and commercial flocks. If genetic improvement in reproduction is important to the breeding objective, it will prove a crucial part of the ram selection criteria and breeding objective. Direct measures that can be utilised on-farm include pregnancy scanning and wet and drying at lamb marking.  

For further information on genetics see MMFS Module 9 Boost Business with Breeding.