Effects of supplemental antioxidants on in vitro fertility measures for cryopreserved boar spermatozoa.

This work aims to evaluate how supplementing a commercial freezing media with butylated hydroxytoluene (BHT), or reduced glutathione (GSH), or their combination affected in-vitro measures of boar sperm after cryopreservation. One ejaculate was collected from 30 high-fertility boars in a weekly collection rotation. Samples were diluted 1:1 in an extender and cooled before overnight shipping at 17 °C to the freezing lab. On arrival, samples were split into the treatments with the following additions before cryopreservation; 1) semen without additional antioxidants (Control), 2) semen with 1 mM BHT, 3) semen with 2 mM GSH, and 4) semen with 1 mM BHT+2 mM GSH. Semen was evaluated for motility kinetics at 30, 120, and 240 min after thawing. Flow cytometry assessments were performed at 60 min after thawing. At all-time points evaluated, total and progressive motility were greater (P ≤ 0.05) in semen cryopreserved with GSH than in Control. No (P > 0.05) differences between Control and other treatment groups were observed in viability, or acrosomal and mitochondrial membrane integrity; however, the proportion of capacitated spermatozoa were reduced (by -21.17%) in semen treated with BHT + GSH compared to Control (P ≤ 0.05). In contrast, there was a higher (P ≤ 0.05, +21.18%) superoxide anion production in the Control than in the BHT + GSH. For IVF, semen cryopreserved with both antioxidants (BHT + GSH) had a negative (P < 0.05) impact on fertilization rate (-54.11%) compared to Control. However, for the blastocysts rate, there were more (+22.75%) blastocysts (P ≤ 0.05) for BHT compared to Control. These results indicate that commercial media supplemented with GSH increased motility but impaired in vitro fertilization rate. On the other hand, media supplemented with BHT improved the in vitro fertilizing ability of the frozen-thawed sperm cells. Therefore, we suggest the supplementation with 1 mM of BHT in the formula of commercial freezing media used in the present experiment.

Fertility responses of melatonin-treated gilts before and during the follicular and early luteal phases when there are different temperatures and lighting conditions in the housing area.

This study was conducted to determine whether exogenous melatonin affected gilt fertility when there were different housing temperature and lighting conditions. Prepubertal gilts (n = 72) were fed (MEL, 5 mg/day) or not fed (CON) melatonin while housed in rooms where temperatures (31.0 ± 1 °C) and daily lighting (240 lx) duration differed: 8 (8 H); 16 (16 H); or 24 (24 H) h in winter and summer replicates. Gilts were moved into rooms (day 1) and administered PG600 on day 6. Gilts detected in estrus were inseminated and slaughtered on day 33 of gestation to determine pregnancy and litter responses. There was no treatment x room effect on estrus (77.8 %), follicle sizes, or number of corpora lutea, but MEL-treated gilts had a longer (P = 0.02) estrous duration (2.0 d) than gilts of the CON (1.7 d) group. Pregnancy rate (92.6 %) and embryo number (13.5) were not affected by treatment or room conditions. There was a treatment x room effect, however, with embryo survival being less (P = 0.01) by ∼23 % in gilts of the CON-24H than CON-16H, MEL-8H, and MEL-24H groups. In the summer replicate, there were also fewer large follicles, a lesser estrous detection percentage, viable embryos, and embryo survival rate than during the winter (P < 0.05). Overall, MEL treatment had positive effects on estrous duration and embryo survival, especially in the summer when there were varying lighting regimens and room temperatures in which gilts were housed.