Principles of Animal Nutrition

Guoyao Wu

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781351646376
• Edition: 1
• Topic: Medicine
• Subtopic: Nutrition, Dietics & Bariatrics

Animals are biological transformers of dietary matter and energy to produce high-quality foods and wools for human consumption and use. Mammals, birds, fish, and shrimp require nutrients to survive, grow, develop, and reproduce. As an interesting, dynamic, and challenging discipline in biological sciences, animal nutrition spans an immense range from chemistry, biochemistry, anatomy and physiology to reproduction, immunology, pathology, and cell biology. Thus, nutrition is a foundational subject in livestock, poultry and fish production, as well as the rearing and health of companion animals.

This book entitled Principles of Animal Nutrition consists of 13 chapters. Recent advances in biochemistry, physiology and anatomy provide the foundation to understand how nutrients are utilized by ruminants and non-ruminants. The text begins with an overview of the physiological and biochemical bases of animal nutrition, followed by a detailed description of chemical properties of carbohydrates, lipids, protein, and amino acids. It advances to the coverage of the digestion, absorption, transport, and metabolism of macronutrients, energy, vitamins, and minerals in animals. To integrate the basic knowledge of nutrition with practical animal feeding, the book continues with discussion on nutritional requirements of animals for maintenance and production, as well as the regulation of food intake by animals. Finally, the book closes with feed additives, including those used to enhance animal growth and survival, improve feed efficiency for protein production, and replace feed antibiotics.

While the classical and modern concepts of animal nutrition are emphasized throughout the book, every effort has been made to include the most recent progress in this ever-expanding field, so that readers in various biological disciplines can integrate biochemistry and physiology with nutrition, health, and disease in mammals, birds, and other animal species (e.g., fish and shrimp). All chapters clearly provide the essential literature related to the principles of animal nutrition, which should be useful for academic researchers, practitioners, beginners, and government policy makers. This book is an excellent reference for professionals and a comprehensive textbook for senior undergraduate and graduate students in animal science, biochemistry, biomedicine, biology, food science, nutrition, veterinary medicine, and related fields.

1

Physiological and Biochemical Bases of Animal Nutrition

The word “animal” is derived from the Latin word animalis, meaning “having breath,” “having soul,” and “living being.” All animals are multicellular, eukaryotic, and motile organisms of the kingdom Animalia (Dallas and Jewell 2014). With adequate intake of nutrients, they survive, grow, develop, and reproduce as important parts of the ecosystem. Animals can be divided into two broad groups: vertebrates (animals with a backbone; e.g., amphibians, birds, fishes, mammals, and reptiles) and invertebrates (animals without a backbone; e.g., corals, clams, crabs, insects, lobsters, oysters, shrimp, spiders, and worms). On the basis of the types of food they consume, animals are classified as (1) carnivores (e.g., cats, dogs, ferrets, minks, and tigers) whose diets consist mainly of nonplant materials (e.g., meat, fish, and insects); (2) herbivores (ruminants [e.g., cattle, deer, goats, sheep, cervids, and New World camelids], horses, and rabbits) whose diets are composed primarily of plant materials; or (3) omnivores (e.g., humans, pigs, poultry, rats, and mice) whose diets include both plant and animal materials (Bondi 1987; Dyce et al. 1996). Among companion animals, cats are obligate carnivores, whereas dogs are facultative carnivores, and these two members of the order Carnivora have very different patterns of nutrient metabolism and requirements.

Wilson (1992) estimated that there were 1,032,000 animal species in nature, including 18,800 species of fish and lower chordates, 9,000 species of birds, 6,300 species of reptiles, 4,200 species of amphibians, and 4,000 species of mammals. Despite the vast diversity among vertebrates and invertebrates, animals exhibit greater similarities in physiology, metabolism, and nutrition than differences (Baker 2005; Beitz 1993; Wu 2013). To date, our understanding of animal nutrition is based primarily on practical feeding and scientific studies of a limited number of terrestrial vertebrate species (including cats, cattle, chickens, dogs, ducks, ferrets, goats, guinea pigs, horses, humans, mice, minks, pigs, rabbits, rats, sheep, and turkeys), and other aquatic and terrestrial species, including fish, shrimp, insects, and Caenorhabditis elegans (Cheeke and Dierenfeld 2010; McDonald et al. 2011; NRC 2002). In recent years, tremendous progress in the nutrition of wild animals has been made (Barboza et al. 2009).

Human civilization has a rich history of studies investigating the nutrient requirements of livestock, poultry, and fish during their life cycle under various physiological and pathological conditions (Baker 2005; Bergen 2007). This is because these agriculturally important animals are the major source of high-quality proteins, as well as vitamins and minerals, for consumption by humans and their companion animals to sustain their optimal growth, development, reproduction, and health (Davis et al. 2002; Reynolds et al. 2015; Wu et al. 2014b). Animal production accounts for 50%–75% and 25%–40% of the total amount of agricultural output in industrialized and developing nations, respectively (Wu et al. 2014a). Thus, research on farm animals has great scientific, social, and economic significance. In addition, rats and mice have long been used as animal models to discover dietary requirements for nutrients and metabolic diseases resulting from their deficiencies. Furthermore, elucidation of metabolic pathways has been facilitated by the occurrence of inherited diseases (knockdown or knockout of genes) in humans and animals (Brosnan et al. 2015; Vernon 2015). Therefore, extensive knowledge exists in the literature regarding the physiological and biochemical bases of nutrition in farm and laboratory animals (Asher and Sassone-Corsi 2015; Dellschaft et al. 2015; Rezaei et al. 2013), as well as humans (Bennett et al. 2015; Meredith 2009). Integration of these large databases provides a strong foundation for this book.

Fundamental Concepts of Animal Nutrition

Definition of Nutrients and Diets

A nutrient is defined as a compound or substance needed to support the maintenance, growth, development, lactation, reproduction, and health of animals. A list of known nutrients required by animals is given in Table 1.1. Food is an edible material that contains nutrients. Food for farm animals (e.g., livestock, poultry, fish, and shrimp) is commonly known as feed. On the basis of their composition and use, feeds are classified as (1) dry forages (e.g., dried pasture, leaves, stems, green chop, and hay) and roughages (e.g., hay, straws, and hulls with >18% crude fiber); (2) gre...