The efficiency of transvaginal oocyte aspiration in Remonta Argentino jennies

Abstract

The donkey population has dramatically decreased during the last years and several species and breeds are considered vulnerable or at risk of extinction. Assisted reproductive techniques, such as transvaginal oocyte aspiration (TVA) and in vitro embryo production, can be used to preserve the genetics of valuable individuals and therefore be implemented in conservation programs. In Argentina, the donkey breed "Remonta Argentina" has been used for mule production since 1920 but no studies have been performed on this breed. Our objective was to compare the efficiency of TVA between female Remonta Argentino donkeys (weight: 320-350 kg and height: 1,42 m) and mixed breed mares (weight: 400-500 kg and height: 1,60 m). TVA was performed in both species as described by Ferrante et al. (Anais do I Simpósio Internacional de Reprodução, Clínica e Cirurgia Equina do Rio de Janeiro. 2019), usingten cyclic jennies and six mares, aspirating follicles between 5 to 25 mm. Data were analysed using a Chi square test and a significance level of 0.05% (p<0.05). A total of 18 TVA sessions were performed in mares, flushing 137 follicles and recovering 97 oocytes (71% recovery rate). In jennies, 39 TVA sessions were performed, flushing 335 follicles and recovering a total of 253 oocytes (75.5% recovery rate). No significant differences were observed in recovery rates between these two species. Our results show that in the Remonta Argentino breed, recovery rates are relatively high and comparable with domestic horses. This makes this breed ideal for obtaining a good number of TVA oocytes to use as a model to improve oocyte maturation and in vitro embryo production in donkeys.