Effect of age, season, breed composition, and sperm counting chamber on boar semen quality in tropics

Understanding the factors affecting semen quality is important for optimizing male reproductive efficiency. The present study aimed to evaluate the seminal quality associated with breed, age, season, and sperm counting chamber in boar ejaculates. A total of 22 sexually mature and healthy boars from maternal and sire commercial breeds were utilized as semen donors, with an average age (mean ± standard deviation) of 21.0 ± 7.2 months. Boars were housed individually in well-ventilated pens and fed a standard breeder mix. Semen samples were collected from each boar in dry and rainy season. The boars were grouped according to age into three categories: <12 months, 12-24 months, and >24 months. Only ejaculates with at least 75 % morphologically normal sperm and more than 8.5 x 109 total sperm per ejaculate were used. The samples were analyzed using the Computer-Assisted Semen Analysis (CASA) ISAS®v1 system. Results showed that younger boars (<12 months) exhibited higher total and progressive sperm motility and faster swimming patterns compared to older boars. The percentages of total motility and fast spermatozoa were increased by rainy season. The kinematics variables showed significant differences (P<0.05) between sperm counting chambers. Duroc and Landrace breeds presented spermatozoa with greater total motility, while terminal sire line breeds showed accelerated linear progressiveness (P<0.05). Overall, the impact of various factors on seminal and kinematic variables in boar ejaculates, including age, season, genetic breed composition, and sperm counting chamber enables to better understand the semen quality of boar ejaculates. This highlights the importance of optimizing swine reproductive management practices in sexually active boars.