肌纤维是肌肉组织的最主要组成部分，可根据其代谢特性、收缩功能和肌球蛋白重链多态性进行不同分类。肌纤维类型及组成与猪肉品质密切相关，因此了解肌纤维的生长发育规律、类型分化与转化及其营养调控，对提高肌肉生长效率和改善肉品质具有重要意义。

The major component of skeletal muscle is the muscle fibers, which can be classified into different types based on metabolic characteristics, contractile properties, and myosin heavy chain polymorphism. The types and composition of muscle fiber are closely associated with pork quality. Therefore, the understanding of muscle fiber development regularity, fiber type differentiation and conversation, and their nutritional manipulation will help to improve efficiency of muscle growth and pork quality in animal production.［Chinese Journal of Animal Nutrition, ２００9，２1（6）:８０３-８０８］