Effect of energy intake during pregnancy and lactation on body composition in rats.

A paired feeding experiment involving high (H) and low (L) feeding levels during pregnancy and lactation was conducted using bred and open female rats to determine the effects on body composition. Pregnant rats contained a higher percentage of water in the fat-free body (FFB) than that of non-pregnant rats indicating tissue hydration. Composition of the FFB and fat-free dry matter (FFDM) was not altered by feeding level during pregnancy. During lactation, the feeding levels were either continued H-H and L-L or were changed to H-L or L-H within the lactating or open (non-lactating) pairs. Composition of the FFB and of the FFDM was altered by feeding level during lactation. A high energy intake result in a greater proportional loss of ash than of protein during lactation. In contrast, neither the composition of FFB nor FFDM was altered in the non-lactating rats on similar energy intake regimes. The lactating females had a higher percentage of water in FFB than the non-lactating rats. Although there was variation in water content of FFB and in the composition of FFDM, the correlation between percentage of body water and body fat after the adjustment of effects of pregnancy, lactation, energy and their interaction, was high (r = -0.98).