Effects of different ages on frozen semen quality and in vitro fertilization efficiency in Wannan black pigs

According to previous studies, the quality and fertilization rate of fresh sperm from boars of different ages were significantly different. However, the difference of freeze–thaw sperm quality and fertility in boars of different ages is unclear. In this study, boars of a Chinese native breed were assigned into two groups. Each group consisted of five boars aged aged either 2–3 years (young boars = YB) or 5–6 years (aging boars = AB) A total of 60 ejaculates for each group were collected and cryopreserved. Semen quality and in vitro fertility of post-thaw sperm was evaluated. The results showed that the concentration and motility of fresh sperm collected from AB were similar to YB, but their semen volume was higher than that in YB (p