Quality of fresh and frozen-thawed semen from Slovak native rabbit and its storage in the gene bank

Abstract

Aim of our work was to compare quality of fresh and frozen-thawed semen of four Slovak native rabbit breeds. In this study, semen from Nitra (n = 4), Zobor (n = 4), Holic Blue (n = 4) and Pastel Rex (n = 2) rabbit breeds was evaluated for possible inter-breed differences in fresh and frozen-thawed sperm quality traits. Individual male semen was diluted (v:v; 1:1) in a freezing medium composed of a commercial diluent, 16 % of DMSO, 4 % of Ficoll 70 and 2 % of sucrose and frozen in liquid nitrogen vapours before plunging into liquid nitrogen (LN2 ). Different motility traits, viability and plasma membrane integrity of fresh and frozen-thawed semen were evaluated in vitro using CASA and flow-cytometry. Our results revealed several differences in motility parameters among the breeds of rabbit. Fresh sperm of Slovak Pastel Rex rabbit showed the lowest (P ≤ 0.05) motility values when compared to the others. In terms of frozen-thawed semen, sperm total motility was similar among Nitra, Zobor and Pastel rabbit, while Holic showed higher (P ≤ 0.05) total motility than Pastel. In addition, Pastel showed the lowest (P ≤ 0.05) progressive movement among the breeds. Similarly to motility analysis, the highest ratio (P ≤ 0.05) of dead sperm and plasma membrane damage among the fresh sperm samples was found in Pastel semen. On the other hand, both Nitra and Pastel rabbits showed lower (P ≤ 0.05) viability of frozen-thawed semen than Holic and Zobor rabbit. In conclusion, this study confirmed variability in quality parameters measured in vitro among four Slovak native breeds of rabbit. Therefore, selection of good-quality insemination doses should be done in order to create a reserve of genetic variability of domestic rabbit in Slovakia.