Fertility reduction due to sub-fertile males is a major concern in breeder flocks. Phenotypic traits of broiler breeder males and their relationships with fertility can be used as reliable indicators for identification and removal of sub-fertile males from the breeder flocks. This study was conducted to investigate semen traits (semen volume, sperm motility, sperm viability and sperm count) and testes histomorphometric features including tubule differentiation index (TDI), spermiation index (SPI), Sertoli cell index (SCI) and mitotic index (MI) of broiler breeder males with the same age but different phenotypic traits. According to phenotypic traits, 12 broiler breeder males (Ross-308 strain) were classified into three equal groups. Group 1: roosters with fertile phenotypic traits (fertile), group 2: roosters with the lowest fertile phenotypic traits (sub-fertile) and group 3: roosters with moderate fertile phenotypic traits (moderate). The results confirmed potential relationship between phenotypic traits and fertility in broiler breeder males. Semen traits and histomorphometric features of broiler breeder males' testis of the group 3 were more similar to those of the fertile roosters. Therefore, it can be concluded that exclusion of these roosters from the breeder flock may have undesirable effects on flock fertility.
Keywords: Breeder male; Histomorphometry; Phenotype; Semen; Testis.