French genetic evaluations on sheep breed stud animals offer a core set of 18 indexes on a wide range of sharply-defined criteria: 7 core–composite indexes put together based on results of individual on-farm and on-station performance testing; 10 core–composite indexes put together based on results of progeny testing.
For dairy sheep breeds, a further 9 production, morphology and composite net merit indexes are calculated.
This enables a breeder to make the best-informed choice based on the combination of traits that best fits their performance targets and priorities.
The Institut de l’Elevage is the official authorized publisher of the French genetic merit indexes for all assessed stud animals in cattle, sheep and goat breeds.
Improving carcass year traits is one of the top-priority selection objectives on specialized sheep-for-meat breeds. The aim is to improve farmed lamb weight gain (which is tied to dam-ewe milk yield value) and carcass quality (fat depth and muscling).
For hardy breeds, which are often exploited as terminal crosses with meat breeds, the selection objectives tend to hinge on improving maternal quality merit traits.
The various different production traits are measured through on-farm performance testing (on maternal value and weight gain traits), individual on-station testing (weight gain, fattening, muscling), plus progeny testing (carcass merit traits and maternal value traits) for certain breeds.
Building on the measurements taken during on-farm performance data recording, the indexes calculated focus on maternal value and weight gain type traits:
Building on the measurements taken at individual on-station testing on young rams, indexes are computed for 4 core meat value-related type traits:
Building on the measurements taken on at least 30 carcasses post-progeny testing, the indexes calculated focus on the following type traits:
A composite (net merit) index (’ISS’) can then be computed from the results for MDWG birth-to-slaughter, conformation, thickness of the back fat cover, and – on option – carcass yield .
There are four indexes on the Lacaune, Pyrenean (Basco-Béarnais and the two Manechs) and Corsican breeds for typing milk value traits:
Furthermore, the Lacaune breed has its own additional set of core and composite indexes: