The Addition of Water to Purified Diets and its Effect upon Growth and Protein Efficiency Ratio in the Rat

The data reported here demonstrated that the addition of 20% of water to a 9% protein purified diet used for protein efficiency ratio (PER) evaluations resulted in a significantly increased rate of gain and a higher PER than that obtained when no water was added to the diet. These effects were also observed at protein levels of 6 and 12% but not at 18%. When either agar, guar gum or gelatinized starch were included in the 9% protein diet, the addition of 20 or 50% of water resulted in an increased rate of gain and a higher PER. The results observed in these experiments emphasize the need for further investigation of the factors involved in PER determination and a possible re-evaluation of previous studies wherein abnormal moisture content may have been observed.