Dispelling myths on external factors affecting post-thawing motility of canine spermatozoa: a retrospective study on 1242 samples

Alessandra Paganotto (1) , Camille Langlade (1) , Emilie Rosset (1) , S. Buff (2, 1)

1 VAS - VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement
2 ICE - Interactions Cellules Environnement - UR

Although the characteristics of canine ejaculates have been the subject of a number of studies, the literature on the influence of donor traits and external factors on post-thawing outcome remains scarce, in particular regarding the possibility of repeating semen collection twice in the same day. The purpose of this retrospective study was to analyse characteristics influencing post-thawing motility. This analysis is based on 1,242 ejaculates frozen at VetAgro Sup between 1995 and 2021. Records included spermatozoa concentration, motility and morphology evaluated at the time of collection and 4 weeks after, age and dog weight, straw size, whether the collection was the first or second of the day and season. Depending on spermatozoa concentration, the ejaculate was divided into 0.25 or 0.5 mL straws. All samples were cryopreserved with a tris-egg yolk and 6% glycerol extender and stored following the same protocol. Thawing control was carried out by placing the straw in a water bath (37°C) for 45 s and motility was analysed after 5 min by at least 2 different clinicians. The influence of external parameters on motility loss was evaluated with ANOVA and Pearson’s r for group differences and variable relationships respectively. The number of collections performed on the same day was only found significantly correlated with the number of spermatozoa (p<0.001), with a lower presence for the second ejaculate. However, the collection repetition was not significantly correlated with post-thawing motility loss. In fact, motility loss did not differ among any of the analysed donor-related and external parameters, ie. age, weight, season, straw size. Recent work on ejaculates collected at short intervals for one cryopreservation process noted that their combination allows a growth in quantity without compromising semen quality. We further observed in our study that the second ejaculate can also be utilised independently without a significant change in post-thawing motility. In addition, we found that neither age, time of the year, dog’s weight, straw size or sperm morphology influenced post-thawing motility loss. Semen cryopreservation in dogs can therefore be performed successfully without these parameters’ influence on the outcome.

Domaines: Médecine vétérinaire et santé animale; Reproduction sexuée; Biotechnologies

Alessandra Paganotto, Camille Langlade, Emilie Rosset, S. Buff. Dispelling myths on external factors affecting post-thawing motility of canine spermatozoa: a retrospective study on 1242 samples. 9th International Symposium on Canine and Feline Reproduction, ICAR 2022 Satellite & 24th EVSSAR Congress, Jun 2022, Milano, Italy. ⟨hal-03720243⟩