above are discussed in greater detail in The Biology of the Guinea Pig (Wagner and Manning, 1976).

Germ-free guinea pigs have been used in the study of specific disease states. Diets for germ-free and specific-pathogen-free guinea pigs have been discussed by Wagner and Foster (1976).

The guinea pig has a mean gestation period of 68 ± 2 SE days (range 59 to 72 days) (Labhsetwar and Diamond, 1970), which may contribute to its advanced development at birth. Dams usually bear 3 to 4 (range 1 to 8) offspring weighing an average of 85 to 100 g each (Ediger, 1976; Sisk, 1976; Apgar and Everett, 1991a). Guinea pigs born weighing less than 50 g have a low probability of survival (Ediger, 1976). Newborn animals can consume semisolid and solid food immediately, although weaning occurs at about 21 days of age when body weight is approximately 250 g (Ediger, 1976). Guinea pigs normally gain as much as 5 to 7 g/day during the rapid growth period when allowed to eat commercial natural-ingredient or purified diets ad libitum (Shelton, 1971; Navia and Lopez, 1973; Jeffery and Typpo, 1982; Liu, 1988; Typpo et al., 1990b). These gains occur routinely and are greater than those obtained with some of the diets used earlier (4 g/day; Woolley and Sprince, 1945). Growth slows after 2 months and maturity is reached at about 5 months. Weight gain can continue until 12 to 15 months of age and levels off at 700 to 850 g for females and 950 to 1,200 g for males (Ediger, 1976). Mating is most often successful when females are 450 to 600 g (2.5 to 3 months old; Ediger, 1976).

Estimates of the energy and nutrient requirements for growth of the guinea pig are presented in this chapter. Considerable variation in requirements can occur as a consequence of several factors—the same as those affecting the nutrient requirements of the rat or mouse: developmental stage, reproductive activity, and age; gender; strain. The nutrient requirements listed in this chapter represent mean values that are thought to be representative but not necessarily sufficient in all circumstances. Further research to quantify nutrient requirements and to identify sources of variation in nutrient requirements of the guinea pig is needed.

Recommendations in this chapter for nutrient concentrations have not been increased to allow a margin of safety for variations in dietary ingredients or for differences among guinea pigs. The data on which requirements are based were reported from several different laboratories using different colony management practices. They are adequate for guinea pigs in most laboratory conditions, but particular laboratory protocols, such as maintenance of germ-free colonies or testing of experimental drugs (see Chapter 1), may alter the requirements for one or more nutrients. The data are not sufficient to differentiate between adult maintenance requirements and growth, pregnancy, or lactation requirements; hence, estimates are provided for growth only (Table 4-1). When data were insufficient to determine requirements, adequate concentrations were determined on the basis of feeding studies that produced adequate growth or on well-established concentrations that produce adequate growth in the laboratory rat. If cited papers provided nutrient intake per day but did not specify

Front Matter (R1-R14)

Overview (1-2)

1 General Considerations for Feeding and Diet Formulation (3-10)

2 Nutrient Requirements of the Laboratory Rat (11-79)

3 Nutrient Requirements of the Mouse (80-102)

4 Nutrient Requirements of the Guinea Pig (103-124)

5 Nutrient Requirements of the Hamster (125-139)

6 Nutrient Requirements of the Gerbil (140-143)

7 Nutrient Requirements of the Vole (144-148)

Appendix (149-153)

Authors (154-156)

Index (157-176)