New method for formulation of amino acid concentrations and ratios in diets of rats

Parameters derived from the application of the saturation kinetics model (SKM) to rat growth experiments were used to formulate a complete dietary amino acid mix for weanling rats. Dietary ratios and concentrations for indispensable amino acids (IAA) and arginine were calculated using the parameter K0.5. A curve shift technique was used to determine dietary concentrations for conditionally indispensable amino acids (CAA) and dispensable amino acids (DAA). The model was also used to determine a dietary ratio of (IAA + Arg)/(CAA + DAA). Using the dietary amino acid concentrations suggested by the model and an (IAA + Arg)/(CAA + DAA) ratio of 1, a growth response curve was constructed and compared to a similar curve using the amino acid mix of Rogers and Harper. The modeling approach produced a 10-15% improvement in growth over the Rogers and Harper mix. The SKM is discussed in terms of calculating an ideal nutrient ratio and choosing a desired response level. It is demonstrated that the model can rapidly produce accurate estimates for dietary amino acid levels, while minimizing required numbers of laboratory animals.