Crystalline amino acid diet for determining amino acid requirements of growing guinea pigs.

Crystalline amino acid diets containing different levels of total nitrogen (TN) and essential amino acid (EAA) nitrogen were evaluated in 3-week growth trials to identify a diet for use in determining the amino acid requirements of growing guinea pigs. Four levels of TN (2.5, 2.9, 3.6, and 4.3%) with constant EAA/TN ratios were compared by measuring weight gain, hemoglobin and hematocrit, carcass weight and nitrogen retention of 3-to 6-week-old male Hartley guinea pigs. Three levels of EAA nitrogen (1.7, 2.0, 2.4%), with TN levels constant at 3.6%, were also compared. A diet containing 30% casein + 0.3% arginine served as a purified control diet. Water and diets were provided ad libitum. The results of this study indicate that a diet containing 3.6% TN and 1.7% EAA nitrogen supported performance comparable to that of animals fed the casein diet. Growth rates for this amino acid diet and the casein diet both averaged 5.8 g/day.