This study aimed to identify motile sperm subpopulations in extended boar semen and to observe the presumptive seasonal variation in their distribution. Data from 4837 boar ejaculates collected over a two-year period were analyzed in terms of kinematic parameters by Computer Assisted Sperm Analysis (CASA). Individual sperm data were used to determine subgroups of motile sperm within the ejaculates using cluster analysis. Four motile sperm subpopulations (SP) were identified, with distinct movement patterns: SP1 sperm with high velocity and high linearity; SP2 sperm with high velocity but low linearity; SP3 sperm with low velocity but high linearity; and SP4 sperm with low velocity and low linearity. SP1 constituted the least overall proportion within the ejaculates (P < 0.05). Season of semen collection significantly influenced the different proportions of sperm subpopulations. Spring was characterized by similar proportions of SP1 and SP4 (NS) and higher proportions of SP3. Summer brought a decrease in both subgroups containing fast sperm (SP1 and SP2) (P < 0.05). During autumn, increases in SP2 and SP4 were recorded. Winter substantially affected the proportions of all sperm subpopulations (P < 0.05) and SP2 became the most represented subgroup, while SP1 (fast and linear) reached its highest proportion compared to other seasons. In conclusion, extended boar semen is structured in distinct motile sperm subpopulations whose proportions vary according to the season of collection. Summer and autumn seem to have a negative impact on the fast and linear subpopulation. Cluster analysis can be useful in revealing differences in semen quality that are not normally detected by classical evaluation based on mean values.

Oxidative stress is associated with impaired post‐thaw sperm quality. As mitochondria are the main source of reactive oxygen species (ROS) in sperm, the goal of this study was to evaluate effects of the mitochondria‐targeting antioxidant Mitoquinone (MitoQ) during cryopreservation of bull sperm. Semen was collected from 11 Simmental bulls (two ejaculates per bull) and diluted in Triladyl^® supplemented with various concentrations of MitoQ (0, 0.2, 2, and 20 nM) to a final concentration of 65 × 10⁶ sperm/ml. After thawing (0 and 3 hr), we assessed the following sperm traits: sperm motility by computer‐assisted sperm analysis (CASA), DNA fragmentation index by SCSA^® and plasma and acrosome membrane integrity, intracellular calcium concentration, esterase activity, mitochondrial membrane potential and synthesis of ROS using two multicolour flow cytometric assays. After 3 hr of incubation, 20 nM MitoQ increased (p < .05) sperm ROS synthesis compared to Control, whereas none of the other quality parameters were altered (p > .05). Therefore, we concluded that addition of MitoQ to semen extender before cryopreservation of bull sperm was unable to improve post‐thaw sperm quality. Furthermore, 20 nM of MitoQ increased frozen‐thawed sperm ROS synthesis, without apparent negative effects on the evaluated sperm traits.

The treatment of cystic ovarian disease (COD) in dairy cows is still controversial, and some researchers recommend using gonadotropin-releasing hormone (GnRH) regardless of the type of cysts. The aim of this study was to comparatively evaluate the reproductive performance of cows diagnosed with follicular or luteal cystic structures, after treatment with either buserelin acetate (GnRH agonist) or dinoprost (prostaglandin F2-alpha or PGF2α). The diagnosis was established by ultrasonographic examinations performed twice a month starting 40-45 days after calving, until the cows were diagnosed pregnant after artificial insemination. Both types of cysts were treated either with 21 µg buserelin acetate or 25 mg dinoprost, resulting in four subject groups. After treatment, the estrus rate in cows with follicular cysts treated with dinoprost (55.1%) was significantly lower (P<0.05) than in cows treated with buserelin acetate (77.5%) or in cows diagnosed with luteal cysts (77.2% for dinoprost and 72.4% for buserelin acetate). The conception rate was higher (P<0.05) in cows with follicular cysts treated with buserelin acetate (67.7%) than in those treated with dinoprost (60%) or in those with luteal cysts (56.9% for dinoprost and 47.5% for buserelin acetate). These results show that it is preferable to differentiate between the two types of ovarian cysts before treatment. Luteal cysts can be treated with either PGF2α or GnRH analogues, with better results when PGF2α is used. Contrastingly, follicular cysts are better treated with GnRH analogues. When differentiation is not possible, GnRH analogues are recommended over PGF2α.