The viability of in vitro produced sheep embryos is negatively affected by the presence of estradiol during in vitro maturation

in Reproduction in Domestic Animals (2005), 40(4), 92

Effet de prétraitements agoniste et antagoniste de GnRH sur la productîon d'embryons chez la brebis et la chèvre

in Proceedings: 8e Rencontres autour des Recherches sur les Ruminants (2001)

ln the superovulated ewe, previous studies have shown that GnRH agonist and antagonist pre-treatment improve embryo production. Consequently, an experiment on this subject was continued in order to ... [more ▼]

ln the superovulated ewe, previous studies have shown that GnRH agonist and antagonist pre-treatment improve embryo production. Consequently, an experiment on this subject was continued in order to simplify GnRH antagonist pretreatment in the ewe, and evaluate the efficiency of this technique in the superovulated goal. For the simplification of the pre-treatment, we compared the efficiency of the multiple low-dose (11' O.5mg/ day) antagonist regimen with a regimen of three injections of 1.5, 0.5, and O.5mgat 5 day intervals. The three injections regimen allowed a high ovulatory response, but a lower yield of transferable embryos (12 vs 8.3 ; P=O.08). GnRH agonist (Decapeptyl) and antagonist (Antarelix) pre-treatments were evaluated in superovulated goats. ln GnRH agonist treated goats (Decapeptyl1.8mg 22days before FSH) follicle number >3 mm was decreased (5.5 before vs 1.1 after treatment ; P<O.Ol) without an effect on the number of small follicles (2-3mm) and ovulatory response. Percentages of recovered and fertilised ova were significantly lower after Decapeptyl pre-treatment than without pre-treatment. Consequently a low number of transferable embryos per Decapeptyl treated goat was obtained (Decapeptyl + FSH: 2.2 vs FSH 4.7 ; P>O.l0). ln GnRH antagonist treated goats (Antarelix Il' 0.5mg / day before FSH) a decrease in follicle number >5 mm was observed as weIl as an increase in small follicle number (2-3mm) and ovulatory response after FSH treatment. However, this beneficial effect on ovulatory response was cancelled by an increase in the percentage of unfertilised ova and degenerated embryos. Consequently, in Antarelix treated goats the yield of embryo production was reduced (Antarelix +FSH 2.3 vs FSH 8.1 ; P<O.Ol). After in vitro fertilisation, the cleavage rate was also lower after Antarelix pre-treatment compared to the control group (84% vs 94%; P<O.Ol). However, this percentage was high (84%) as compared to the in vivo fertilisation rate (29%).A negative effect of Antarelix pre-treament on goat oocytequality is possible; nevertheless, transport and survival of spermatozoa in the genital tract are most probably affected in these conditions [less ▲]