Candidate genes were found on ROH islands in various breeds, and their association with important traits were highlighted (e.g., ABCA7 with JER milk protein content; PENK with behavior fear response in BRA; SPP1 with mammary health status in IND; IFNAR1 and IFNAR2 with immune system features in TAB; SPEF2 with male infertility in both CCD and CCB; and PRLR with milk production in CCD; LRRTM1 and LRRTM4 with negative regulation of JAK-STAT cascade in CUR). The gene discussed is SPEF2; the disease is male infertility.