A SUCROSE-DMSO EXTENDER FOR FREEZING RABBIT SEMEN

The aim of this study was to define a simple extender for freezing rab bit semen from selected males used to inseminate selected does to obta in embryos for an embryo bank. Four experiments were carried out. In t he first experiment, freezing extender was defined on the basis of the results of the post-thawing motility rate. Three factors and their in teractions were studied: final concentration of dimethyl sulphoxide (D MSO) (1, 1.25, 1.5 and 1.75 M), egg yolk (0% of 10 v/v) and sugar (non e, or 0.5 M of glucose, lactose, sucrose, or maltose). The sucrose and 1.75 DMSO improved significantly the post-thawing motility rate (sucr ose 1.75 M DMSO extender. 42 +/- 3%). In the second experiment, this f reezing extender was used to freeze semen from three lines. The post-t hawing motility and normal acrosome rates were similar among the lines when the covariates, fresh motility and normal acrosome rates, respec tively, were used in the analysis (52 +/- 1 and 66 +/- 1%, respectivel y). In the third experiment, frozen semen from the White New Zealand l ine (NZ) was tested by morphological normality and viability of embryo s recovered. Recovery data from NZ does inseminated with fresh and fro zen semen were compared. No significant differences were found in the number of normal embryos obtained per donor doe (8.9 +/- 0.5) and in t heir survival after vitrification (52% of live foetuses at 29 days of gestation). The sucrose-DMSO extender and freezing procedure used in t his work can offer satisfactory results to apply in conservation and g enetic programmes.