Changes in Total Body Water and Dry Body Weight with Age and Body Weight in Friesians and Water Buffaloes

Ninety Friesian and 153 Water Buffalo cows, 6 to 60 months and 100 to 500 kg body weight, were used in this study.Total body water was determined by 3H-radioisotope dilution technique and dry body weight deduced by subtracting total body water from live body weight.In Friesians and Buffaloes there were significant positive correlations (P < 0.01) between age and each of live body weight (r : 0.7228, 0.8990), dry body weight (r : 0.6728, 0.8305), and total body water in liters (r : 0.3860, 0.6150), whereas there were significant negative correlations (P < 0.0]) between age and total body water in liters/ :100 kg live body weight (r:0.2968,--0.3795) and in liters/]00 kg dry body weight (r : --0.2427, --0.2990).Moreover, live body weights in Friesians and Buffaloes were positively correlated with dry body weight at P < 0.01 (r : 0.8450, 0.9167) and with total body water in liters at P < 0.0i (r : 0.8972, 0.9508).Linear regressions were made for each of live body weight, dry body weight, and total body water, in liters, liters/100 kg live body weight, and liters/100 kg dry body weight, on age, as well as for each of total body water in liters, and dry body weight on live body weight.Growth is commonly estimated by the increase in live body weight, which comprises total solids and total body water.Water retention is "known to vary considerably between animals during growth, due to difference in the rate of accumulation of the less hydrated fat, collagen, and fibrous tissues in replacement of the more hydrated functioning protoplasmic mass, and to the age difference in response to nutritional and climatic factors.It seems, therefore, that dry body weight would represent a better index than live body weight for an accurate estimation of growth in living animMs.The objective of this study was to determine the change in dry body weight, total body water,