Effect of recipient doe genotype on survival rate at birth of frozen rabbit embryos

The effect of the genotype of 2 selected rabbit strains (White New Zealand and Synthetic) on the survival rate at birth of frozen embryos was studied. Morulae were obtained 64-66 h postcoitum from 32 multiparous does naturally mated with males of the same strain (16 does of Synthetic strain (SY) and 16 does of the White New Zealand strain (NZ)). Morphologically normal morulae were slowly frozen in 1.5 M DMSO and stored in liquid nitrogen. After thawing, intact embryos from both strains were transferred into the oviducts of 32 recipient does of both strains (16 SY strain does and 16 NZ does). Significant differences were observed in pregnancy rate and survival rate at birth between strains of recipient does. The recipient does of the SY strain showed a higher pregnancy rate than those of the NZ strain (87.5% versus 25% respectively; P < 0.05). When the survival rate at birth was analyzed in all recipient does, this was found to be 28 +/- 4% in SY recipient does versus 8 +/- 4% in NZ recipient does (P < 0.01). However, when the survival rate was analyzed in pregnant recipient does, no significant differences were found between embryo strains and recipient strains, the average survival rate was approximately 32%. The major factor in the differential survival rate between SY and NZ embryos was due to the genotype of recipient does.