Porcine intramuscular fat content and composition are regulated by quantitative trait loci with muscle-specific effects

Intramuscular fat (IMF) storage is a biological process with a strong impact on nutritional and technological properties of meat and also with rel- evant consequences on human health. The genetic ar- chitecture of IMF content and composition phenotypes has been thoroughly studied in pigs through the iden- tification of QTL and the estimation of genetic param- eters. A question that has not been elucidated yet is if the genetic determinants of IMF-related phenotypes are muscle specific or, conversely, have broad effects on the whole skeletal muscle compartment. We have ad- dressed this question by generating lipid QTL maps for 2 muscles with a high commercial value, gluteus medius (GM) and longissimus thoracis et lumborum (LTL), in a Duroc commercial population (n = 350). Our data support a lack of concordance between the GM and LTL QTL maps, suggesting that the effects of poly- morphisms influencing IMF, cholesterol, and fatty acid contents are modulated to some extent by complex spa- tial factors related to muscle location, metabolism, and function. These results have important implications on the implementation of genomic selection schemes aimed to improve the lipid profile of swine meat. © 2011 American Society of Animal Science, All rights reserved.