Sheep embryos derived from FSH/eCG treatment have a lower in vitro viability after vitrification than those derived from FSH treatment

In the non breeding period, the effect of two superovulatory treatments (eC G/FSH in single dose or FSH alone in four decreasing doses) on the producti on of embryo quality following in vitro viability after vitrification proce dures was investigated using forty-four adult Sarda breed ewes. In sheep tr eated with eCG/FSH, the mean number of corpora lutea was significantly (P<0 .05) higher (11.8<plus/minus>4.0 vs. 8.05 +/-3.8), although the recovery ra te was significantly (P<0.01) lower (74.6 vs. 59.9) than with FSH alone. Af ter vitrification (ethylene glycol and glycerol) was repeated three times, the rates of re-expansion at first and second warming were significantly (P <0.01) higher in embryos derived from FSH alone than in those with both gon adotrophins (94.9 and 41.9 vs. 72.8 and 18.6) and after the last vitrificat ion the hatched blastocyst rates were 22.5 and 7.6. After differential stai n, blastocysts derived from FSH alone showed a mean number of cells signifi cantly higher than blastocysts from eCG/FSH (184.2 vs. 157.7). It was concl uded that superovulatory treatment with eCG/FSH may increase the ovarian re sponses compared with FSH alone, but these embryos showed a reduction in vi ability rates after repeated vitrification.