Effect of the porcine IGF2-intron3-G3072A substitution in an outbred Large White population and in an Iberian x Landrace cross.

The IGF2-intron3-G3072A substitution has been recently described as the causal factor of the imprinted QTL for fat deposition and muscle growth detected within the porcine IGF2 region. The objective of this study was to investigate the IGF2 substitution effect in a Large White outbred population and in an Iberian x Landrace F2 cross. The results showed that the substitution has significant effects on fatness, growth, and shape traits with estimated effects in the expected direction. These results agree with those obtained in the F2 cross, where the IGF2-intron3-G3072A substitution is segregating only in a small family. In addition, a QTL scan has been performed in the F2 population for the traits used in the IGF2 substitution effect validation. Results of this study demonstrated that there are QTL segregating in swine chromosome 2 other than the IGF2 substitution for carcass weight, LM area, and pH measured at 24 h after slaughter. The results confirm the relevance of the IGF2 substitution, but they also show that there are still valuable mutations to be revealed in this chromosome.