Articles

Ovulation rate and embryo survival in the pig : genetic aspects

Abstract

Current knowledge on the genetic variation in ovulation rate (OR) and embryo survival (ES) is reviewed. Between-breed range of variation is high for both traits (from 8 to 10 ovules and 20 to 25 percentage points for OR and ES, respectively). Direct heterosis effects are quite small (2-3 % for OR ; 1-2 % for ES). On the other hand, embryo survival exhibits an important maternal heterosis effect (about 8 % ). The heritability of ovulation rate is relatively high (0.30). The heritability of embryo survival is less well established, but it seems comparable or slightly higher than values obtained for prolificacy (about 0.15). The genetic correlation between OR and ES is negative, but both traits have positive relationships with litter size. The few available estimates unfortunately do not allow to specify their size. Otherwise, relationships with the Major Histocompatibility Complex (SLA) and reciprocal translocations have been demonstrated. Other links are suspected with the H blood-group and the transferin locus. Potential improvements in litter size from using these omponents are then discussed. Some prospects are likely to exist, but no conclusion can currently be drawn, due to our limited knowledge on the genetic variation in OR and ES and problems encountered with modelling embryo survival.

Authors


J.P. BIDANEL

bidanel@inra.fr

Affiliation : INRA Station de Génétique quantitative et appliquée, 78350 Jouy-en Josas

Country : France

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