Early embryonic survival and embryo development in two divergent lines of rabbits selected for uterine capacity

¹ Departamento de Ciencia Animal. Universidad Politécnica de Valencia. P.O. Box 22012. 46071 Valencia. Spain

^* To whom correspondence should be addressed. E-mail: ropeibar{at}dca.upv.es.

	Abstract

The aim of this work is to study early embryo survival and the development stage of embryos in two lines divergently selected for high (H) and low uterine capacity (L) throughout 10 generations. A total of 162 female rabbits from the H line and 133 from the L line were slaughtered at 25, 48 and 62 h of gestation. There were no differences in ovulation rate (OR) and fertilization rate (FR) between lines in any of the three stages of gestation. Embryo survival (ES), estimated as the number of normal embryos recovered at a constant ovulation rate, was similar in both lines at 25 and 48 h. Embryo survival was higher in the H line (0.57 embryos) at 62 h of gestation. There was no difference in embryonic stage of development at 25 h, but at 48 and 62 h of gestation, the H line had a higher percentage of early morulae (83% versus 72%) and compacted morulae (55% and 38%) respectively. Divergent selection by uterine capacity appeared to modify embryo development, at least from 48 h of gestation, and embryo survival from 62 h.

Key Words: uterine capacity, selection, early embryo survival, embryo development, rabbit