Developmental body of composition of the squirrel monkey (Saimiri sciureus).

The longitudinal growth of 69 newborn squirrel monkeys fed control semipurified diets from birth as well as the developmental chemical analysis of 51 carcasses is reported. Males were significantly heavier than females at birth and every age thereafter. Exponential curves fitted to the first two years of life in each sex showed that age and weight were highly correlated (R2 = 0.999). Therefore, the four major carcass components (water, protein, fat and ash) were expressed as a function of a single variable--body weight. Water and protein content were linearly related to body weight over a wide range of growth whereas fat and ash were more variable. Using linear regression analysis, no sex differences were found. On a percentage basis, body fat content was uniformly low (2.7%) at birth and increased to variable levels thereafter. Therefore, the subsequent analyses were done on a fat-free basis. Per cent protein (nitrogen X 6.25) increased from 16.3 at birth to 23.8% at adulthood with water decreasing from 76.4 to 68.9%. The protein:water ratio was 0.213 at birth and increased to an adult value of 0.345. The developmental curves indicated that approximately 70 to 75% of this maturation occurred in the first 3 weeks of life and was completed on, or before, 20 weeks of age. Per cent ash increased significantly from 4.41 at birth to 5.10% at adulthood.