Correlated responses to selection for intramuscular fat in several muscles in rabbits

The aim of this study was to evaluate the effect of six generations of selection for intramuscular fat (IMF) in muscle Longissimus thoracis et lumborum (LTL) at 9 wk. in IMF and fatty acid (FA) composition of muscles with diverse metabolic profile in rabbits. Direct response to selection was 0.33 g of IMF/ 100 g of LTL, around 0.4 SD per generation. A positive correlated response was observed in IMF of Biceps femoris, Supraspinatus and Semimembranosus proprius muscles at 9 wk., representing around 0.2 SD of the trait per generation. Selection affected similarly the FA composition of all muscles at 9 wk., high-IMF line showing greater monounsaturated but lower polyunsaturated FA percentages than low-IMF line, whereas no differences were observed for saturated FA. Traits were also measured at 13 wk. and correlated responses were in the same direction. Our results suggest a common genetic background for IMF and FA composition in muscles with different metabolic profile in rabbits.