Abstract
Sperm motility is a key determinant of male fertility and is regulated by coordinated interactions within the spermatogenic niche. To investigate the basis of sperm motility divergence in geese, 60 ganders with sperm motility values within the physiological range were ranked, and the top and bottom 10% were assigned to high-sperm-motility (H) and low-sperm-motility (L) cohorts (n = 6). Semen characteristics, testicular histology, and plasma endocrine, antioxidant, and metabolic indices were compared between cohorts, and for single-cell RNA sequencing, three ganders were selected from each cohort to form the H and L groups for testicular analysis. Compared with the L cohort, the H cohort showed significantly higher sperm motility, semen volume, testis weight, testicular parenchyma area, seminiferous epithelium thickness, seminiferous tubule diameter, and plasma levels of testosterone, luteinizing hormone, total antioxidant capacity, superoxide dismutase, catalase, albumin, and high-density lipoprotein cholesterol, but significantly lower testicular interstitium area, and plasma levels of prolactin, corticosterone, malondialdehyde, H(2)O(2), and glucose. Single-cell transcriptomic profiling identified the major testicular cell populations and indicated that differences in sperm motility were most strongly associated with round spermatids, elongated spermatids, Sertoli cells, and Leydig cells. In the H group, round spermatids were enriched in pathways related to axoneme and cilium organization, oxidative phosphorylation, and protein folding and translation, consistent with enhanced sperm structural maturation. Sertoli cells displayed enhanced tight-junction, glycolytic, and glutathione-metabolism signatures, suggesting improved barrier integrity, redox buffering, and a lactate-associated metabolic bridge that supports developing germ cells. Leydig cells exhibited enhanced pathways related to steroidogenesis, mitochondrial respiration, and redox homeostasis. In contrast, elongated spermatids in the L group retained broader mitochondrial, cytoskeletal, and protein quality-control signatures, suggesting delayed or less efficient terminal maturation. Overall, these findings suggest that high sperm motility in geese may be associated with enhanced endocrine-metabolic support within the somatic niche and stronger axonemal assembly-related programs during late spermatid maturation, providing single-cell-resolved insights into cellular states associated with fertility variation in early mature ganders.