Preface

Skeletal muscle is the single largest organ mass in the vertebrate body. As a source of food, it represents most of the value in a meat-producing animal. Both the growth characteristics of muscle and the quality of the resulting meat determine the ultimate worth of a carcass. In recent years, tremendous strides have been made in the field of muscle biology, particularly in our understanding of the mechanisms controlling skeletal muscle growth and development, and the impact these factors have on meat production and quality. Many of the past difficulties that meat and animal scientists have experienced when attempting to address specific problems (e.g., stress susceptibility and poor meat quality in swine) have been due to a lack of understanding the underlying biological mechanisms driving muscle growth, metabolism, and its conversion to meat. This book is designed to provide the advanced reader with state-of-the-art knowledge about skeletal muscle and meat, and also as a platform for further investigation of specific issues. At the same time, this comprehensive review provides the newcomer with a sound background in applied muscle biology and meat science.

Chapter 1 provides a detailed analysis of muscle structure with an emphasis on muscle proteins, microstructure, membrane composition, and contraction. This discussion lays the groundwork for succeeding chapters.

An understanding of the growth and development of skeletal muscle and some of its components such as fat and connective tissue is crucial to our ability to manipulate production of the meat animal and subsequent meat quality characteristics.

Chapters 2 through 7 address issues relevant to muscle growth and development. Accordingly, myogenesis and the biology and nature of satellite cells are reviewed. Adipogenesis, essential for muscle development and growth and so critical to meat quality, is discussed in Chapter 3. Chapter 4 reviews current issues related to the fetal stage of muscle development, with emphasis on the sensitivity of the fetus to maternal nutritional status and resulting fetal programming of skeletal muscle. The characteristics of muscle fiber types and mechanisms of in vivo protein degradation are the subjects of Chapters 5 and 6. Finally, a discussion of collagen and other matrix constituents and their contribution to muscle growth and quality concludes this part of the book.

Chapters 8 through 14 review key aspects of postmortem changes in mammalian and fish muscle that are responsible for meat quality characteristics. Thus, the first chapters in this middle section discuss, arguably, the two most important biological changes in postmortem muscle: proteolysis and glycolysis. A recurrent problem in the production of pork has been superior lean growth coupled with the development of poor quality "acid meat." Chapter 10 reviews recent research related to alterations in protein signaling pathways that are related to development of this genotype in pigs. Color has been recognized for decades as one of the premier quality traits of meat. Chapter 11 presents a comprehensive review regarding mechanisms governing meat color. Chapter 12 discusses multiple factors responsible for lipid oxidation in meat and strategies for its prevention. Recognition of the beneficial properties of specific fatty acids in meat has prompted interest in components such as ω-3 long-chain polyunsaturated fatty acids and conjugated linoleic acids. Chapter 13 reviews recent progress in nutritional management for enrichment of these meat constituents and the subsequent impact on meat quality. This section concludes with Chapter 14, a comprehensive review of the unique fish myotome and the postmortem changes it undergoes.

The penultimate chapter (Chapter 15) addresses molecular techniques that are increasingly utilized in breeding programs, including molecular mapping and marker-assisted breeding. Finally, the book concludes with an essay (Chapter 16) dedicated to animal welfare and the ethics of using animals for food, an especially timely discussion given the concerns of animal rights activists.

In summary, this book focuses on biological changes in skeletal muscle and meat. Given recent developments in energy costs and distribution, and changes in the commodities markets driven by the demand for biofuels, the challenges for animal production agriculture will only increase. Increased appreciation for the underlying biological mechanisms related to animal and meat production can only help solve the challenges. Thus, this book is suitable as a text for advanced courses in applied muscle biology and meat science; it further serves as a reference for scientists and industry personnel involved in meat science, as well as animal growth and development.