Body Cell Mass and Lean Body Mass in the Growing Beagle 1

Summary

The lean body mass (LBM) was considered equivalent to fat-free wet weight (FFWW), and it decreased from 97% of body weight at birth to 85% when the pups were 1.5 mo old, after which it did not change significantly throughout the rest of the growth period. The body cell mass (BCM) was calculated by three methods: ICW/0.70, [K/(K/N)]×25, and LBM –ECT. The BCM calculated from ICW/0.70 did not change significantly with growth, and a mean of 48% was calculated from 0 day to 1 yr. With the other two methods of calculating BCM, there was a significant increase between the third and fourth months. The equation [K/(K/N)]×25 gave a mean BCM of 24% for 0 day to 3 mo and 41% from 4 mo to 1 yr, while the means calculated from LBM – ECT for the corresponding periods were 30 and 41%. Before chemical maturity the two methods gave significantly different results, but their agreement after chemical maturity was fortuitous. The increase in BCM between 3- and 4-mo-old dogs when calculated from total K was accounted for by a significant increase in K at chemical maturity, while the increase in BCM when calculated from LBM – ECT was the result of a reduction in ECW (percentage of body weight).