Divergent selection for uterine capacity in rabbits. II. Correlated response in litter size and its components estimated with a cryopreserved control population1

Abstract

Our objective was to evaluate the correlated responses to selection for litter size and its components after 10 generations of divergent selection for uterine capacity (UC). A total of 294 intact females from the 11th and 12th generations of divergent selection for high and low UC and from a cryopreserved control population was used (139, 112, and 43 females, respectively). Uterine capacity was assessed as litter size in unilaterally ovariectomized females. Traits recorded on females for up to five parities were litter size (LS) and number born alive (NBA). Laparoscopy was performed in all females at d 12 of their second parity, and the ovulation rate (OR) and number of implanted embryos (IE) were recorded in these females. Embryo survival (ES = IE/OR), fetal survival (FS = LS/IE), and prenatal survival (PS = LS/OR) were computed. Correlated responses in LS and in its components were inferred using Bayesian methods. Correlated responses in LS were asymmetric. The divergence between high and low lines was 2.35 kits, mainly because of a higher correlated response in the low line (1.88 kits). The lower LS in the low line was associated with a lower PS (control - low = 0.14), because of decreases in ES and FS.

Identification of differentially expressed genes in the oviduct of two rabbit lines divergently selected for uterine capacity using suppression subtractive hybridization

“…In conclusion, the present study provides a list of candidate genes differentially expressed in the oviduct of two lines of rabbits divergently selected for UC. The genes overexpressed in the L line seem to be related to a decrease of early embryo development and survival, in agreement with previous results found in this line Mocé et al 2005;Santacreu et al 2005;Peiró et al 2007). However, further studies are necessary to elucidate the relevance of those genes and proteins on rabbit reproductive traits.…”

“…However, when only RT-qPCR expression values from the females used for SSH construction (3 from each line) were analyzed, both genes exhibited higher levels of expression (1.5 fold and 2-fold increase in OVGP1 and ANXA1 expression, respectively) in the H line compared with the L line (data not shown). Several factors may explain this result including: 1) a sampling effect in the selection of the animals for SSH, 2) the inclusion in the RT-qPCR analysis of animals with less extreme phenotypes or 3) divergent selection for UC was more effective in the L line than in the H line (Argente et al 1997;Santacreu et al 2005;Mocé et al 2005) and hence, animals from the H line showed more variability in gene expression because they may be less genetically uniform than L animals. Of the 3 validated genes by RT-qPCR from L line, HSD17B4 and PGR are involved in "reproductive development process".…”

Identification of Single-Nucleotide Polymorphism in the Progesterone Receptor Gene and Its Association With Reproductive Traits in Rabbits

“…This difference was approximately half of the difference found using intact does (2.35 kits; Santacreu et al 2005).…”

“…The high (H) line showed a higher litter size (2.35 kits in intact females) and also a higher number of embryos before implantation (1.8 embryos in intact females) than the low (L) line . This difference was not due to a higher ovulation rate (Mocé et al 2002;Santacreu et al 2005) or fertilization rate (Santacreu et al 1996), both of which were similar in both lines. A difference of 1 embryo between lines was observed at 72 hr of gestation in favor of the H line, using intact does (Mocé et al 2004).…”

“…There were no relevant differences in fertilization rate at both 48 and 72 hr of gestation between homozygote genotypes, P s ¼ 100%. We consider 0.25 embryos as a relevant value for EES since we found half of the difference in the number of implanted embryos between the H and L lines at 72 hr of gestation (Mocé et al 2004;Santacreu et al 2005). We did not find a relevant difference between the GG and AA genotypes for EES at 48 hr of gestation, but the precision of the estimation was low.…”