Effect of Pig Domestication on Skeletal Muscle Development, Microstructure, and Genetic Mechanism Involved in Myofibre Type Formation

The wild boar and modern highly selected pigs are phenotypically distant European pig breeds reared in contrasting conditions and present ideal model to better understand the mechanisms behind meat quality deterioration related to domestication and selection pressure, which provoked substantial modifications in the ontogenic development as well as contractile and metabolic properties of skeletal muscles. The skeletal muscle of domestic pigs are less mature at birth and contains a lower number of myofibres compared to wild boars; however, expansive myofibre hypertrophy, protein accretion as well as additional myofibre formation are accelerated in the early postnatal period in some muscles in domestic pigs. A comparative view of the cellular and subcellular mechanisms underlying the skeletal myofibre development could help to design a breeding program that would improve the balance between the growth performance, muscularity and meat quality. This chapter therefore outlines the influence of domestication on myofibre formation and differentiation during growth and provides a comparative view on the developmental expression pattern of the MyHC isoforms, the activity of different metabolic enzymes, and the expression of selected genes responsible for the metabolic diversity of the myofibres. Additionally, there is a special emphasis on the type, composition, and histomorphological traits of myofibres.