Pregnancy rate after fixed-time transfer of cryopreserved embryos collected by non-surgical route in Lacaune sheep
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Figueira, Lucas Machado
Alves, Nadja Gomes
Batista, Ribrio Ivan Tavares Pereira
Brair, Viviane Lopes
Lima, Renato Ribeiro
Oliveira, Maria Emilia Franco [UNESP]
Fonseca, Jeferson Ferreira
Souza-Fabjan, Joanna Maria Gonçalves
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This study investigated the feasibility of applying fixed-time (cryopreserved) embryo transfer in ewes. Embryos (n = 106) were non-surgically recovered from superovulated donors (n = 39) on day 6–7 after oestrus. Straws containing one or two embryos (morulae and/or blastocysts) subjected to either slow freezing (SF, n = 62) or vitrification (VT, n = 44) were randomly used within fixed-time embryo transfer on Day 8.5. Recipient ewes were nulliparous (n = 58) bearing corpora lutea after synchronous oestrous induction protocol. The pregnancy rate was higher (p =.03) in SF (39.4%) than VT (16.9%) and survival rate tended (p =.08) to be higher in SF than in VT (25.8% vs. 15.9%). Lambing rates were similar (p =.13) between SF (20.9%) and VT (15.9%). Embryos recovered by non-surgical route after cervical dilation treatment and later cryopreserved by either slow freezing or vitrification produced reasonable pregnancy rates after FTET.
embryo cryopreservation, multiple ovulation and embryo transfer, ovine
Reproduction in Domestic Animals.