Challenges for local breed management in Mediterranean dairy sheep farming: insights from Central Greece.

Local breeds are recognized as an important element for the maintenance of various and specific farming systems. Challenges for local breeds' management, in a context of crossbreeding with exotic highly productive breeds, have been mainly studied in tropical countries. However, similar situation and challenges are likely to exist in Mediterranean countries subjected to climatic and feed scarcity issues. The objective of this work is to identify the challenges for local breed management in a regional context of informal crossbreeding with highly productive breeds. For this purpose, the case of dairy sheep farming in the region of Thessaly, in Central Greece, was examined. Semi-structured interviews were performed in 46 farms and processed through hierarchical classification on principal components. A follow-up on seven farms raising the Karagouniko sheep breed, the main local breed of the region, was carried on during one milk campaign. Results showed that a diversity of breeding strategies involving local purebred and crossbred flocks coexist in the region. The Karagouniko breed is facing several challenges. The supply in exotic breeding males and their crosses could be wide-scaled and involved a diversity of operators, whereas the supply in breeding males of Karagouniko breed was restrained to between-farm supply among flocks under milk recording scheme. In addition, the heterogeneity of access and quality of collective rangelands affected the farming of Karagouniko breed ewes, whose purebred flocks were significantly associated with the grazing on native grasslands. Finally, unfavorable dairies' policies led Karagouniko farmers to seek higher flock milk production through levers that could impact the vulnerability of the farm, such as earlier lambing period or earlier weaning age. Farmers also questioned the use of highly productive breeds as a potential lever to reach higher flock milk production.

A genomic map of climate adaptation in Mediterranean cattle breeds.

Domestic species such as cattle (Bos taurus taurus and B. t. indicus) represent attractive biological models to characterize the genetic basis of short-term evolutionary response to climate pressure induced by their post-domestication history. Here, using newly generated dense SNP genotyping data, we assessed the structuring of genetic diversity of 21 autochtonous cattle breeds from the whole Mediterranean basin and performed genome-wide association analyses with covariables discriminating the different Mediterranean climate subtypes. This provided insights into both the demographic and adaptive histories of Mediterranean cattle. In particular, a detailed functional annotation of genes surrounding variants associated with climate variations highlighted several biological functions involved in Mediterranean climate adaptation such as thermotolerance, UV protection, pathogen resistance or metabolism with strong candidate genes identified (e.g., NDUFB3, FBN1, METTL3, LEF1, ANTXR2 and TCF7). Accordingly, our results suggest that main selective pressures affecting cattle in Mediterranean area may have been related to variation in heat and UV exposure, in food resources availability and in exposure to pathogens, such as anthrax bacteria (Bacillus anthracis). Furthermore, the observed contribution of the three main bovine ancestries (indicine, European and African taurine) in these different populations suggested that adaptation to local climate conditions may have either relied on standing genomic variation of taurine origin, or adaptive introgression from indicine origin, depending on the local breed origins. Taken together, our results highlight the genetic uniqueness of local Mediterranean cattle breeds and strongly support conservation of these populations.