Breeding objectives and reasoned strategy of implementation at the population level for French dairy sheep breeds

Abstract

One of the limiting factors identified in the 1950’s was low milk yield level of the French dairy ewes, which initiated the collaboration between breeder organizations and researchers that has been developed. Initially, the two possible genetic strategies, crossbreeding or purebred selection, were investigated. Finally the breeders chose in the 1970’s the selection of each local French dairy sheep breed in its specific area of production related to its PDO cheese. The success of the selection of the five involved local breeds is the result of a rationalized and optimized approach, in space (pyramidal management of the population), and in time (progressiveness of the breeding goals from milk yield only to global merit giving the same weights to milk traits and udder functional traits). This approach was validated by permanent exchanges between private and experimental flocks: it permits, on the one hand to conceive and validate simplified tools such as lactation sampling for fat and protein contents, and SCC, and on the other hand to understand the originality of the dairy selection environment when management decisions are taken at the flock level and not individually, which may induce sustainable indirect genetic responses (feed intake ability, milking speed, once daily milking ability) used by the breeders. This rationalized approach does not preclude the implementation of other solutions to address a strategic and unforeseen new goal, such as scrapie resistance in the 1990’s. For each of the five local breeds, diversification of new breeding objectives (once daily milking ability, functional longevity, milk persistency, resistance to gastrointestinal strongyles) is likely to occur since the 2015 starting of genomic selection in French dairy sheep breeds.