This was a common criterion used for animals. The question arises, however: Is maximum optimum?
For human infants, requirements are estimated from the amount of each nutrient in the quantity of human milk ingested by infants whose growth rates are satisfactory. This is not generally the maximum rate.
The criterion of growth rate of breastfed babies was disputed even in fairly recent times, and mothers of breastfed infants were sometimes made to feel inadequate if their babies did not gain weight at the abnormally high rate seen in typical bottle-fed infants.