Supplementation of Beltsville extender with quercetin improves the quality of frozen-thawed rooster semen.

1. Excessive reactive oxygen species (ROS) production during the sperm freeze-thawing process leads to membrane lipid peroxidation, DNA damage, and motility loss.2. This study examined the effect of supplementation of Beltsville poultry semen extender with different concentrations of quercetin (and antioxidants) on the cryopreservation of rooster sperm.3. Semen samples were collected from six Ross broiler breeders via abdominal massage twice a week for 4 weeks (eight replicates), and were divided into five equal aliquots to be diluted in Beltsville extenders that contained different concentrations of quercetin: 0, 5, 10, 15, and 20 mM. Motility, membrane functionality, abnormal morphology, lipid peroxidation, mitochondrial activity, viability, apoptosis status, and fertility potential were assessed post thaw.4. The addition of 10 and 15 mM quercetin to the semen extender significantly increased the total motility, straight-line velocity (VSL), and sperm membrane functionality compared with the other groups (P ≤ 0.05). Moreover, 10 mM quercetin caused higher progressive motility (34.86 ± 3.80%), curvilinear velocity (VCL; 175.11 ± 3.20 µm/s), average path velocity (VAP; 44.35 ± 11.06 µm/s), viability (59.14 ± 1.36%), mitochondrial activity (80.14 ± 2.07%), lower abnormal morphology (19.21 ± 0.45%), and lower lipid peroxidation (2.7 ± 0.13 nmol/ml) compared with the other groups (P < 0.05). The rate of fertility and hatchability after artificial insemination was not affected by experimental groups.5. In conclusion, supplementation of Beltsville extender with 10 mM quercetin could be a suitable method to improve post-thawed rooster sperm quality resulting in better freeze/thaw characteristics.