Identification of Selection Signatures for Milk Performance Traits among Indigenous Dairy Cattle Breeds using High Density Genomic Information

Selection process for milk performance traits has left remarkable selection signatures in the genome and their identification can guide to utilize under genomic breeding programs for improving productivity in dairy cattle.

This study utilizes genotype data of Sahiwal (19), Tharparkar (17) and Gir (16) to identify selection signatures in the genomes of Sahiwal-Gir (SW-GR), Sahiwal-Tharparkar (SW-TP) and Tharparkar-Gir (TP-GR) breed pairs by using F_ST approaches. The highest F_ST peaks (F_ST >0.25) were considered as selection signature region. The functional genes underlying signature regions controlling milk performance traits were also annotated.

We identified 41, 29 and 60 selection signatures exhibiting footprints of positive selection among SW-GR, SW-TP and TP-GR breed pairs, respectively. The selection signals controlling milk performance traits were detected as ACADL, SLC26A2, PLCB1, SYT9 genes mapped on chromosome 2, 7, 13 and 15, respectively for SW-GR breed pair. Selection signature regions in the genome of SW-TP breed revealed genes ATPAF1, LEF1, PPARGC1B, EIF6 and ACSS3 for milk production. Furthermore, PLA2R1, SCP2, ATPAF1, CACNA2D1, LEF1 and SUMF1 genes were identified in TP-GR breed pair controlling metabolism and morphogenesis of mammary gland. Moreover, HSPB6, LTBP1, SLIT3, FSHR and ASIP genes were also found in association with thermo-tolerance, disease resistance, immunity, reproduction and coat colour in our indigenous dairy cattle breeds.