Laboratory housing conditions and water and food intake are all important factors that should be considered when designing an experiment because they may have different physiological and psychological effects on rodent which can also affect the outcome of the study.

Laboratory rodents are usually on one kind of diet throughout their whole life (complete life-cycle diet). For this reason, the careful choice of the diet is crucial in maintaining healthy rodent stock in animal facilities. The food chosen for long term feeding should contain enough protein, fat, minerals, and other ingredients which are necessary for reproduction and growth in conventional, specific-pathogen-free (SPF), or germ-free environments where the intestinal flora is undefined, defined, or absent, respectively. The reason why the different manufacturers nutrition parameters are varying (in some cases between batches as well) is that the nutrient content of the processed raw seeds, depend on the season, and different storage conditions.

Therefore, it can be stated that most of them have appropriate nutrition profiles for complete life-cycle feeding.

Nutritive requirements for laboratory mice:

Proteins
The requirement for protein to support maximal growth or reproduction depends on the content and digestibility of the amino acids in the diet and the growth and reproductive potential of the mice in question (Keith and Bell, 1988). The protein requirements for reproducing mice depends on the mouse strain, it should be between 16.7% to 24%, while for growth, the requirements are 14–20% (Nutrient Requirements of Laboratory Animals,Fourth Revised Edition, 1995).

Lipids
Lipids are important components of the mouse diet because they provide essential fatty acids and a concentrated energy source. The lipids also helps in the absorption of fat-soluble vitamins. Unsaturated fatty acids, such as linoleic and linolenic, are dietary requirements of mice (Decker et al., 1950; Bell, 1962; Morris, 1944). A diet with a fat concentration of 5% is recommended for feeding different mice strains.

Carbohydrates
The diets usually contain high concentrations of carbohydrates and starch. However, studies showed that diets with high concentrations of fructose or sucrose increased liver fatty acid synthesis and decreased extrahepatic fatty acid synthesis as opposed to diets high in glucose or starch (Herzberg and Rogerson, 1982).

Minerals
Wolinsky and Guggenheim (1974) and Ornoy et al. (1974) reported that Swiss mice consuming a diet containing only 0.2 g Ca/kg showed signs of calcium and phosphorus deficiency and experienced decreased weight gain, bone ash, and serum calcium. It has also been reported, that diets containing 4.0 to 8.0 g Ca/kg and 3 to 12 g P/kg support growth and reproduction in mice (Morris and Lippincott, 1941; Mirone and Cerecedo, 1947; Wolinsky and Guggenheim, 1974; Bell and Hurley, 1973).

Vitamins
Little work has been done to establish the different requirements of water-soluble and fat-soluble vitamins of the laboratory mice and they vary widely among different studies (Bell, 1962; Cuthbertson, 1957; Lane-Petter, 1963; Porter and Lane-Petter, 1962; Spector, 1956). The amounts of these essential ingredients in a diet are dependent on availability for absorption, presence or absence of antagonists, and balance or equilibrium (Albanese, 1963).

Fiber
Although a fiber source is routinely included to increase bulk in diets for mice, and it is a potentially beneficial dietary constituent in lower percentages (3-4%) in high concentrations it depresses performance.

Summary

The appropriate nutrition of experimental animals during their complete lifetime is an important issue for successful animal maintenance and accurate experimentation. The adequacy of diets needs to be examined from different aspects. Besides reproduction and growth several other criteria like longevity, nutrient storage, enzyme activity should be taken into consideration. Diets which support maximal growth are not necessarily optimal for reproduction. Therefore, the nutrition needs of different animal strains and/or ages could to be different, but the parameters stay between minimal and harmful ranges.