118 W. M. Wallace, W. B. Weil and A. Taylor 



mixture (NaHCOg, 7-4 g.; KCl, 12-0 g.; CaCOg, 12-0 g.; 

 (NHJaHPO^, 14-9 g. ; MgSO^, 2-5 g.; KI, 0-001 g.) to pro- 

 duce the compositions shown in Table I. The salt mixture 

 was compounded to imitate the ion ratios found in fat- 

 free cow's milk. Ferrous sulphate, 2-0 g., copper sulphate, 

 • 22 g. and aureomycin, • 25 g. per kg. of diet were incorpor- 

 ated in the mixtures. A vitamin mixture (Vitamin Diet 

 Fortification, Nutritional Biochemicals Corporation) in quanti- 

 ties calculated to make all diets equal in this respect was 

 added to the mixtures. 



* Moisture + Fibre (calculated by difference) 



Prior to the beginning of the feeding experiments, all 

 animals had been weaned to a commercially produced small 

 animal feed (Friskies, The Carnation Milk Company) known 

 to produce excellent growth, general health and reproduction 

 in the albino rat. Preliminary feeding trials with the high 

 protein experimental diets in comparison with the Friskie 

 diet indicated equal effectiveness as measured by weight gain, 

 general appearance, activity, gentleness and lack of morbidity. 



Eight groups of animals were studied, namely : 



1. Weanling group (WEAN) 70-80 g. rats weaned to 

 Friskies. 



2. High Protein-High Electrolyte (HPHE), see Table I 



3. High Protein-Low Electrolyte (HPLE), see Table I. 



4. Low Protein-High Electrolyte (LPHE), see Table I. 



5. Low Protein-Low Electrolyte (LPLE), see Table I. 



