Effect of rabbit line on a program of cryopreserved embryos by vitrification

Abstract

-The aim of this study was to assess the application of a cryopreservation program to preserve two selected rabbit lines. One of them was selected by litter size at weaning, line V (Synthetic breed). The second, line R (synthetic breed), was selected by growth rate. In this study, embryos were collected, from donor does belonging to the 7th and 15th generations of lines R and V, respectively, were vitrified and were stored from 1992-1993. Those embryos from donor does belonging to the 17th and 21st generations of lines R and V respectively, were vitrified and sotred from 1998-1999. Embryo transfers were carried out in 1999. Morphologically normal embryos at the morulae stage were cryopreserved by vitrification in a 2.8 M dimethyl-sulfoxide + 3.5 M ethyleneglycol + 0.3 g·L -1 bovine serum albumine in Dulbecco phosphate buffered saline solution. The main problem in the cryopreservation program was the low embryo production efficiency: significant differences were obtained in recovery efficiency between lines and line R showed the lowest proportion of donor does with 55% (at least 4 normal embryos) vs. 72% in line V. However, after transfer in recipient does of line V, the fertility rate at birth (81%), the rate of alive born by pregnant recipients (43%) and the number of males and does with offspring (9 to 18 different males, 12 to 32 females) enabled the different generations from each line to be re-established and studies on the selection process genetic gain to be developed. cryopreservation / embryo / line / rabbit

Embryo vitrification in rabbits: Consequences for progeny growth

“…The effect of the genotype on the rederivation efficiency of cryobanked embryos in the rat, mouse, and rabbit has been observed [3,[12][13][14]. In fact, Vicente et al [15] reported that cryopreserved embryos from paternal rabbit lines (selected for growth characteristics) showed reduced survival rate after transfer (10% less) compared with cryopreserved em-bryos from maternal lines (selected for reproductive char-acteristics such as litter size at birth or at weaning). One management tool used to achieve higher survival rates after thawing consists of transferring the embryos of paternal lines to recipient does from a maternal line.…”

Effect of Feed Restriction in a Rabbit Line Selected for Growth Rate on Reproductive Performance: Ovulation Induction, Oocyte Quality, Embryonary and Fetal Losses

“…When line R does are induced to ovulate with GnRH analogues, no significant failures are observed in ovulation frequency: between 95-100% of AI females treated with a GnRH analogue ovulated (Viudes-de-Castro et al, 1995;Mehaisen et al, 2004;Vicente et al, 2003Vicente et al, :2012. Additionally, the GnRH analogue injected after AI could increase systemic LH blood concentrations and could promote more LH receptors in the follicles than GnRH naturally secreted after natural mating (Pieper et al, 1981).…”

“…Specifically, paternal rabbit lines selected uniquely for growth rate are characterised by elevated growth rate and adult live weight , but reduced reproductive performance (Mehaisen et al, 2004;Vicente et al, 2012). In previous studies comparing paternal and maternal rabbit lines, differences have been reported in ovulation frequency, ovulation rate, prenatal survival, gestational losses and consequently in litter size (Vicente et al, 2003;. Specifically, works carried out with line R, selected by weight daily gain, reported severe reproductive characteristics.…”

“…Nevertheless, estimates of genetic correlation in rabbits between the litter size and growth traits are low and contradictory, as the magnitude and the sign of the correlations could depend on the correlated reproductive trait, as well as the population or strain under study. In previous studies comparing paternal and maternal lines, differences have been reported in ovulation frequency, ovulation rate, gestational losses and consequently in litter size (Vicente et al, 2003;. Recent estimations of the effects of inbreeding on litter size exclude it as the factor explaining the differences observed between the paternal and maternal lines (Gadsby et al, 1983).…”

“…These ovulation failures were related to reduced LH plasma concentrations when females did not ovulate naturally, while in all line R does induced to ovulate with GnRH analogues ovulation occurred in 95-100% (Viudes- de-Castro et al, 1995;Vicente et al, 2003;Naturil-Alfonso et al, 2016). It has been shown that fasting modifies the responses of the anterior pituitary gland to GnRH activity, leading to a reduced synthesis of LH by pituitary cells Ferguson et al, 2003).…”