Abstract
The young rats were fed for 60 days on diets containing 7.5% casein at three levels of caloric intake; 100, 80 and 60% of full caloric requirement. Nitrogen balance, urinary nitrogenous and liver components were determined after 30 and 60 days from initial feeding of experimental diets. (1) The growth after 60 days was proportional to the level of caloric intake. Apparent digestibility of protein and apparent retention
Ingested N-(Fecal N+Urinary N)/Absorbed N×100
were unaffected by the caloric intake levels except some detailed points. (2) Each of the percentages of urinary amino, allantoin and creatinine nitrogens to total nitrogen among each group was compared. It was found from the data after 30 days that these values were decreased by caloric restriction. These data show the tendency that the characteristic pattern of urinary nitrogenous components of rats fed on low protein diet is lost by caloric restriction. (3) Glycogen content in dried liver was decreased and inversely protein content was increased by caloric restriction. The deposition of more than 20% of liver fat was found in all groups, and remarkable effect of caloric intake levels on the fat deposition was not found from the data after 30 days. It was found that the moisture percentages of wet liver of rats after feeding for 60 days were increased by caloric restriction.
