Non-additive effects of RBP4, ESR1 and IGF2 polymorphisms on litter size at different parities in a Chinese-European porcine line

Background The aim of this work was to study the effects on litter size of variants of the porcine genes RBP4, ESR1 and IGF2, currently used in genetic tests for different purposes. Moreover, we investigated a possible effect of the interaction between RBP4-Msp I and ESR1-Pvu II polymorphisms. The I...
Ausführliche Beschreibung

Background The aim of this work was to study the effects on litter size of variants of the porcine genes RBP4, ESR1 and IGF2, currently used in genetic tests for different purposes. Moreover, we investigated a possible effect of the interaction between RBP4-Msp I and ESR1-Pvu II polymorphisms. The IGF2-intron3-G3072A polymorphism is actually used to select lean growth, but other possible effects of this polymorphism on reproductive traits need to be evaluated. Methods Detection of polymorphisms in the genomic and cDNA sequences of RBP4 gene was carried out. RBP4-Msp I and IGF2-intron3-G3072A were genotyped in a hyperprolific Chinese-European line (Tai-Zumu) and three new RBP4 polymorphisms were genotyped in different pig breeds. A bivariate animal model was implemented in association analyses considering the number of piglets born alive at early ($ NBA_{12} $) and later parities ($ NBA_{3+} $ ) as different traits. A joint analysis of RBP4-Msp I and ESR1-Pvu II was performed to test their possible interaction. In the IGF2 analysis, paternal or maternal imprinting effects were also considered. Results Four different RBP4 haplotypes were detected (TGAC, GGAG, GAAG and GATG) in different pig breeds and wild boars. A significant interaction effect between RBP4-Msp I and ESR1-Pvu II polymorphisms of 0.61 ± 0.29 piglets was detected on $ NBA_{3+} $. The IGF2 analysis revealed a significant increase on $ NBA_{3+} $ of 0.74 ± 0.37 piglets for the paternally inherited allele A. Conclusions All the analyzed pig and wild boar populations shared one of the four detected RBP4 haplotypes. This suggests an ancestral origin of the quoted haplotype. The joint use of RBP4-Msp I and ESR1-Pvu II polymorphisms could be implemented to select for higher prolificacy in the Tai-Zumu line. In this population, the paternal allele IGF2-intron3-3072A increased litter size from the third parity. The non-additive effects on litter size reported here should be tested before implementation in other pig breeding schemes. Ausführliche Beschreibung