Influence of pharmacological experiments of chemicals and other factors in diets of laboratory animals

Abstract

Results derived from animal experimentation depend to a considerable degree on the health and welfare of the animal from which the results are obtained. This, in turn, reflects the quality of housing, care, and nutrition provided the animal. Most diets designed for a particular species provide a reasonable balance of nutrients in quantities sufficient for normal growth and maintenance and reproduction of that species. Under usual conditions of animal feed manufacture, however, concentrations of essential ingredients may vary appreciably in different batches of a formulation made with different lots of natural ingredients, even though the guaranteed analysis shown on the label remains correct. A feed may also contain intentional or unintentional additives and other biologically active components. Variations in the concentrations of essential dietary components, as well as the presence of extraneous materials, can significantly influence the performance of an experimental animal consuming the diet and can thus lead to a biased interpretation of esperimental results. Investigators must consider factors which can result in efficient or inefficient utilization of energy, the variation in prepared diets whether from natural or purified products, and how these can modify the animal and change the response to a given experimental regimen. Proteins, fat, carbohydrates, vitamins, and minerals can all have pharmacological as well as physiological effects on a biological system. The control of vitamin D metabolism and calcium, parathormone, calcitonin among others are important factors subject to dietary modification. A conditioned marginal or frank deficiency of folic acid can result from oral contraceptives and administration of anticonvulsants; if studies are done in animals using these types of chemicals, dietary folate will be highly significant. Newer information about the role of ascorbic acid in activation of lipase and lipid mobilization is of direct concern to those using research animals requiring a source of dietary ascorbic acid. Trace elements, some amino acids, natural enzyme inducers, and toxic contaminants, all of which can affect the response of experimental animals, are highly important to the quality of animal research in pharmacologic investigations.