This fourth revised edition of Nutrient Requirements of Laboratory Animals integrates new information gained in the latest review of the world literature on nutrient requirements of laboratory animals. At our request many individuals provided the subcommittee with published materials from theses and other sources not recovered in a standard literature search.

The committee sought to make this publication a valuable reference to investigators whose expertise was other than nutrition. Examples of natural-ingredient and purified diets reported in the literature are provided. The subcommittee attempted to maintain clarity by identifying the chemical nature of the minerals and vitamins used in supplements to the diets. In addition, in the tables the subcommittee elected to use mass units of measure that can be used directly by diet manufacturers with minimal calculation. Molar and other units of measure can be found in the discussions included within each chapter. The references used in each chapter are listed as part of the chapter rather than compiled in a master reference list.

The intent of Chapter 1 is to provide a general narrative with critical references for those who are looking for a basic understanding of the formulation of diets for the expected feeding of laboratory animals used in biological research.

Chapter 2, which focuses on the laboratory rat, contains new information on amino acid, fatty acid, mineral, and vitamin requirements. To the extent possible, requirements for maintenance, growth, and reproduction are presented separately. A new section entitled ''Potentially Beneficial Dietary Constituents" was included because these materials cannot be shown to be a dietary essential although their inclusion may be beneficial to animals maintained in laboratory settings. Examples of natural-ingredient diets and purified diets that can be used to support animals on long-term studies are also presented. These diets have been shown to be effective for the commonly used strains of rats and mice.

Chapter 3 focuses on the laboratory mouse and integrates new information to create an updated nutrient requirements table along with summary tables of sources used to estimate protein and amino acid requirements for various strains. As with the rat, those ingredients for which a requirement cannot be shown are included in the section on potentially beneficial dietary constituents.

The new information on the guinea pig is presented in Chapter 4, which also includes a new section on growth and reproduction and a new natural-ingredient diet and additional purified diets. In addition to updating the requirements reported previously, estimates are now available for the requirements for indispensable amino acids. A table summarizing the sources used to estimate protein and amino acid requirements is part of this chapter.

Chapter 5 summarizes the latest update on hamsters. New sections and summary tables on the origin of hamsters, their biological characteristics, growth, and reproductive development are included. New purified diets and a natural-ingredient diet that can be used for long-term studies are presented. A nutrient requirements table is not included. Few, if any, studies devoted to determining the nutrient requirements of the hamster could be found. The subcommittee concluded that the hamster, partly because of pregastric fermentation, is sufficiently different from the mouse and rat so that requirements identified for these species should not automatically be applied to the hamster.

Chapter 6 contains data on the gerbil. Information on the biology and origin of gerbils used in research is included. Little new information on nutrient requirements could be found.

Chapter 7 focuses on voles. New sections on the biological characteristics and husbandry are incorporated in this edition. The limited information available on the voles' requirement for various nutrients is presented in the text.

New appendix tables are provided, detailing the amino acid and fatty acid composition of some ingredients commonly used in purified diets as well as molecular weights and international unit standards of various forms of vitamins. These tables may be of assistance in formulating purified diets.