Effect of Dietary Supplementation with Salmon Oil on Canine Frozen–Thawed Semen

The objective of this study was to evaluate the effect of omega-3 oral supplementation on frozen–thawed semen quality in stud dogs. Nine healthy male dogs of various ages (2–11 years old), weights (10–36 kg), and breeds were included. Their daily diets were supplemented with salmon oil at 180 mg DHA/7 kg BW. Semen was collected before salmon oil oral administration (D0), after 90 days of daily administration (D90), and 90 days following suspension (D180). Samples underwent standard freezing procedures and were stored for at least 30 days; then, they were thawed at 37 ◦C for 1 min. Samples (n = 27) were assessed post-thawing for motility (MOT%), membrane integrity (HOST%), and viability (EN%). A second aliquot of the same samples underwent a thermoresistance test at 37 ◦C, with MOT% and EN% evaluated at 2 and 4 h post-thawing. Data were analyzed using repeated measures ANOVA, considering days of administration (D0, D90, D180), incubation times at 37 ◦C (T0h-T2h-T4h) and their interaction. Significance was set at p < 0.05. An increase in MOT% was observed after 90 days of fish oil administration (D0 = 56.67 ± 5.1% vs. D90 = 71.67 ± 5.1%, p < 0.05); however, this effect was not maintained at D180 (45.56 ± 5.1%). Similar results were observed for HOST and EN. During the thermoresistance test, a significantly higher MOT% was observed at T4h on D90 compared to D0 (p < 0.05). These findings indicate that daily salmon oil supplementation at 180 mg DHA/7 kg for 90 days improves semen motility, membrane integrity and viability, supporting a role for omega-3 fatty acids in semen undergoing cryopreservation.