Hybrid Vigour

Many traits can be easier to improve through crossbreeding and the exploitation of hybrid vigour alongside within-breed selection using EBVs.

Hybrid vigour is the improvement in performance that is achieved by a crossbred over and above the average performance of its two purebred parents.



Whilst hybrid vigour can enhance growth and carcase traits, it has far more impact on low heritability traits influencing reproductive performance and longevity, these include:

  • Lamb survival
  • Ewe fertility
  • Ewe prolificacy
  • Ewe survival and longevity
Producers breeding their own female replacements need to consider whether these are to be purebred or crossbred.

Advantages of breeding purebred females

  • Simple system, where only one breed is required
  • Potential marketing advantages from purebred sales
  • Greater uniformity amongst breeding and sale stock
Advantages of breeding crossbred females
  • Exploitation of hybrid vigour
  • Wide access to different genetics
  • Faster potential rates of genetic change
Breeding strategies can be developed to incorporate hybrid vigour into the genetic makeup of both the ewe and the lamb.



Breeders can enhance important traits like ewe fertility and longevity by exploiting hybrid vigour.