Influence of different eCG doses on the rabbit doe ovary response, fertilizing aptitude and embryo development

Abstract

[EN] The aim of this experiment was to compare the ovary response, the fertilising aptitude and the embryo development of multiparous rabbit does having received during the whole career 0 (control: no injection, group 0), 8 or 25 IU of eCG (groups 8 and 25, respectively) 48 h before each 4 d post partum insemination. After the 11th series of insemination, two groups of 60 does were sacrifi ced 30 h or 14 d after insemination. The percentage of ovulating females does not vary according to the eCG treatment, but the ovulation rate (number of corpora lutea per ovulating does) and the fertilising rate (number of segmented ova/number of corpora lutea x100) increases with eCG dose [10.2, 11.1, 12.3 corpora lutea (P=0.011); 61.6 vs 97.5, 81.2% (P<0.001), for groups 0, 8 and 25 IU respectively]. In a same way, at 14 d of pregnancy, the embryo survival (1-(number of corpora lutea ¿ number of alive embryos/ number of corpora lutea)) increases with the injected amount of eCG (55.1 vs 69.9 and 83.1% for groups 0, 8 and 25, respectively, P=0.023). Moreover, eCG completely removes the fertilising failure independent of ovulation. Compared with the other does, lactating-non-receptive does have a lower fertilisation rate (70.0 vs 90.2%, P=0.008) and a weaker embryo survival (55.3 vs 83.5%, P<0.001). It is concluded that with intensive reproduction rhythm (4 d post partum insemination), an 8 IU of eCG injected 48 h before insemination is enough to enhance the ovulation rate, the embryo survival and the fertilisation rate of multiparous does.