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Genetic Parameters and Genomic Markers Associated with Mastitis Resistance in Dairy Sheep
Monthly records of four mastitis related traits and milk yield were analyzed for 609 Chios dairy ewes raised in four flocks in Greece. Heritable variation was observed in milk somatic cell count, total viable bacterial count in milk and California mastitis test results, especially in early and late lactation. Between animal repeatable variation was also observed in clinical mastitis in addition to these traits. All animals were genotyped with a 960-SNP DNA array including polymorphisms that had been found to have a significant effect on mastitis traits in three other exotic breeds. A genome-wide association study revealed 22 SNP with a significant effect on at least one of the traits studied in this independent population. The significance of 18 of these SNP, located on chromosomes 2, 5, 16 and 19, was confirmed with an ensuing mixed model analysis. None of these SNP affected milk production.
Keywords:
sheep, mastitis, markers
