Sport improves function of roosters testicular Leydig cells by mediating FUNDC1

Roosters play a crucial role in breeder chicken production. A decline in reproductive performance during the late breeding stage is a major factor limiting economic returns. Testosterone, a key hormone for maintaining secondary sexual characteristics and supporting spermatogenesis, is primarily synthesized and processed within mitochondria. With advancing age, mitochondrial function deteriorates in roosters, leading to reduced testosterone synthesis and impaired reproductive capacity. This study aimed to elucidate the mechanisms through which rest and sport affect the reproductive performance of aging roosters. A total of 36 Tianfu Pink roosters aged 110 weeks were allocated into three groups with three replicates per group. After a 4-week intervention involving rest and sport regimens, natural mating was conducted to collect reproductive performance data. The results showed that rest and sport exerted anti-inflammatory effects, significantly improved semen quality and hatching performance, increased serum levels of testosterone and gonadotropins, enhanced systemic antioxidant capacity, and markedly upregulated FUNDC1 expression in the testes. In primary chicken testicular interstitial cells, overexpression or knockdown of FUNDC1 significantly enhanced or suppressed mitochondrial function, as well as the expression of genes and proteins related to antioxidant defense and testosterone synthesis. Moreover, FUNDC1 overexpression alleviated rotenone-induced mitochondrial damage and restored testosterone synthesis in testicular interstitial cells. These findings suggest that sport may enhance testosterone synthesis in testicular interstitial cells by modulating FUNDC1 expression, thereby improving mitochondrial function and antioxidant defense. This study provides theoretical and technical insights for improving the reproductive performance of breeding roosters during the late production phase.