Known mutation (A3072G) in intron 3 of the IGF2 gene is associated with growth and carcass composition in Polish pig breeds

IGF2 is one of the genes that control muscle development. Moreover, IGF2 is imprinted, as only the paternal allele is expressed in the offspring. Using real-time PCR for IGF2 genotyping (Carrodegous et al. 2005), we evaluated the frequency of the IGF2 A3072G mutation (Van Laere et al. 2003) in pigs: Polish Landrace (PL, N = 271) and Large White (LW, N = 267). Our results are consistent with previous reports, showing that the A allele is common in breeds Subjected to strong selection for lean meat content (A allele frequency was 0.79 in LW and 0.69 in PL). Moreover, we compared body composition, growth performance and meat quality traits in pigs carrying opposite genotypes (A/A and G/G) in the IGF2 gene. The association study revealed that the A allele increases the weight of loin (WL) (additive gene effect = 450 +/- 50 g in LW and 213 +/- 64g in PL), weight of ham (WH) (544 +/- 48 g in LW and 302 +/- 72 g in PL), loin eye area (LEA) (4.9 +/- 0.46 cm(2) in LW and 2.1 +/- 0.95 cm(2) in PL), carcass meat percentage (CP) (3.12 +/- 0.27% in LW and 1.89 +/- 0.47% in PL), and decreases average backfat thickness (ABF) (-0.2 +/- 0.036 cm in LW and -0.2 +/- 0.048 cm in PL). Additionally, in PL, the A allele increases the weight of tenderloin (WT) (11 +/- 0.01 g), average daily gain (ADG) (30.7 +/- 17.29 g), and decreases feed intake (F) (-121 +/- 45 g) and days of feeding (DF) (-3.5 +/- 2.08 days). No significant effects were observed for meat quality traits. Our results Suggest that selection based on the IGF2 mutation in Poland may be very useful in PL and LW pigs, where the G allele is still relatively frequent.