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The genomic architecture of mastitis resistance in sheep

Genetics study helps scientists understand mastitis resistance.

A flock of sheep.

Mastitis, caused by bacterial infection of the udder, is the most prevalent disease in dairy sheep and has major economic, hygienic and welfare implications.

Scientists and animal breeders believe that marker assisted breeding for enhanced mastitis resistance may provide a means to control the disease, alongside optimized management practices. This approach requires the identification of the genes and genomic regions driving mastitis resistance.

Using non-invasive tests (milk somatic cell count, total viable bacterial count in milk and the California mastitis test) data was collected for mastitis traits in 609 Greek Chios ewes. The ewes were genotyped using a custom-made DNA array based on quantitative trait loci (QTL) for mastitis resistance. We then conducted genomic association studies to identify genomic regions significantly associated with mastitis resistance in this validation population.

The expression of candidate genes for mastitis resistance identified within the detected genomic regions was measured in immune related tissues and cells and the mammary gland using the sheep gene expression atlas dataset, also produced by researchers at the Roslin Institute. Using this approach scientists were able to identify pathways, molecular interaction networks and functional gene clusters related to mastitis resistance. 

Their findings have potential applications in marker based assisted breeding for mastitis resistance.

Further work will investigate the expression of genes in genomic regions associated with milk yield and highlight any potential correlation with mastitis resistance.

Original Publication:

Banos et al. 2017 The genomic architecture of mastitis resistance in dairy sheep, BMC Genomics, 18:624, https://doi.org/10.1186/s12864-017-3982-1

Related links:

Sheep gene insights could help farmers breed healthier animals