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 Zea land and Synthetic) on the survival rate at birth of frozen embryos wa s studied. Morulae were obtained 64-66 h post-coitum from 32 multiparo us does naturally mated with males of the same strain (1 6 does of Syn thetic strain (SY) and 16 does of the White New Zealand strain (NZ)). Morphologically normal morulae were slowly frozen in 1.5 M DMSO and st ored in liquid nitrogen. After thawing, intact embryos from both strai ns were transferred into the oviducts of 32 recipient does of both str ains (1 6 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 highe r pregnancy rate than those of the NZ strain (87.5% versus 25% respect ively; 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 ve rsus 8 +/- 4 % in NZ recipient does (P < 0.01). However, when the surv ival rate was analyzed in pregnant recipient does, no significant diff erences were found between embryo strains and recipient strains, the a verage survival rate was almost-equal-to 32%. The major factor in the differential survival rate between SY and NZ embryos was due to the ge notype of recipient does.