Effects of the porcine IGF2 intron 3-G3072A mutation on carcass cutability, meat quality, and bacon processing

A SNP in a regulatory region of intron 3 within the porcine IGF2 gene (IGF2-G3072A) is associated with increased lean deposition and decreased fat deposition in pigs with paternal A alleles (A(Pat)) compared with pigs with paternal G alleles (G(Pat)). However, data regarding fresh and processed meat quality characteristics of pigs with different alleles for this polymorphism are limited. A single heterozygote (AG) boar was bred to homozygous (AA) commercial Yorkshire-cross sows producing F-1 barrows and gilts with either G(Pat) or A(Pat). Two farrowing groups of barrows and gilts were group housed, provided ad libitum access to a diet that met or exceeded NRC nutrient recommendations throughout production, and slaughtered at 176 d (+/- 4 d) of age. Fresh LM quality and estimated percent fat-free lean measurements were taken on the left side of carcasses, while carcass cutouts were completed with right sides. Fresh belly and bacon processing traits were characterized for only block 1 pigs. Pig was treated as the experimental unit for all analyses. Ending live weight and HCW were not affected by IGF2 allele; however, 10th rib backfat thickness was 0.41 cm less (P = 0.01), loin eye area was 4.0 cm(2) greater (P = 0.01), and predicted fat-free lean was over 2 percentage units greater (P < 0.01) in A(Pat) pigs compared with G(Pat) pigs. Furthermore, boneless lean cuts from the shoulder, loin, and ham were heavier (P < 0.05) in A(Pat) pigs compared with G(Pat) pigs. Minolta L* value was 2.36 units greater (P = 0.03) but cooking loss was 1.82 percentage units greater (P < 0.01) in A(Pat) pigs compared with G(Pat) pigs. Additionally, despite reductions in subcutaneous fat, extractable intramuscular lipid from the LM was 0.64 percentage units greater (P = 0.02) in A(Pat) pigs compared with G(Pat) pigs. Bellies were 7.17 mm thinner (P = 0.01), had 7.27 cm less flop distance (P = 0.05), and tended to have 1.34 units greater iodine value (P = 0.09) in A(Pat) pigs compared with G(Pat) pigs. While not statistically different (P = 0.30), the magnitude of difference in slicing yield as a percentage of green weight was 1.57 percentage units between bellies from A(Pat) pigs (85.83%) and bellies from G(Pat) pigs (87.40%). Pigs with G(Pat) had superior belly quality that may positively impact commercial bacon production. However, pigs with A(Pat) yielded a greater amount of lean product at the expense of producing lighter LM color and increased cooking loss.