Differences in semen quality, testicular histomorphology, fertility, reproductive hormone levels, and expression of candidate genes according to sperm motility in Beijing-You chickens

Sperm motility is used to predict the semen quality and fertilization ability of breeder roosters. Indigenous chicken breeder roosters show variation in sperm motility, but less has been known about its relationship with other reproductive attributes. In this study, 40- to 44-wk-old Beijing-You breeder roosters with the high and low sperm motility phenotypes (n = 15 in each group) were identified and compared, with regard to their semen characteristics, reproductive hormone concentrations, testicular histomorphology, fertility capacity, and genes expression of hematopoietic prostaglandin D synthase (H-PGDS) and wingless-type MMTV integration site family, member 2 (WNT2). The low sperm motility roosters showed lower semen volume (P = 0.003) and sperm viability (P = 0.008). Like semen donors in the artificial insemination test, the low sperm motility roosters showed lower fertility than the high sperm motility roosters (P < 0.001). No difference in the serum concentration of follicle stimulating hormone (FSH, P = 0.347), luteinizing hormone (LH, P = 0.376), or testosterone (T, P = 0.068) was found between the high and low sperm motility roosters. Furthermore, among roosters with similar BW, the low sperm motility roosters had smaller testis mass (P = 0.037), seminiferous tubules diameter (P = 0.031), spermatogenic epithelium height (P = 0.001), and Johnsen score (P = 0.005) than the high sperm motility ones. Finally, the expression of both H-PGDS and WNT2, which are involved in the prostaglandin D₂ and WNT signaling pathways, respectively, was low in the testis of the low sperm motility phenotype roosters (P < 0.05). Thus, the findings of the present study indicated that the testis of low sperm motility showed impaired testicular histomorphology as compared to normal; the BW, testis weight, and serum FSH, LH, and T levels are associated with sperm production, but not with sperm motility, and that low expression of H-PGDS and WNT2 may be related with the abnormal testicular morphology of low sperm motility birds which deserves further functional validation studies.