Studies on the chemical composition of the rat body during growth and development

Studies of the chemical composition of the rat body during growth and development. Acta Physiol. Pol., 1977, 28 (6): 559-573. Changes in the content of nitrogen, ether extract, water and ash in the body of rats were examined from the 1st to the 265th day of their life under conditions optimal for maximal growth and development. The investigations were carried out on 203 male Wistar rats kept on a standard diet containing about 20% of protein and 3.2 kcal ME/g. The diet was available ad libitum. After a period of fasting the animals were sacrificed at definite time intervals, their bodies were autoclaved and homogenized. The results of chemical analyses were processed statistically using logarithmic values and linear regression equations for all components in relation to the total (shrunk) and fat-free body mass, and for the relationship between the different components. The results obtained indicate that the values of all components related to the total or fat-free body mass show a curvilinear course of changes, which can be described with the power function Y = axb.