Four female Holstein cattle (Holstein, average body weight (BW) 359 kg), four castrated male native cattle (Native, 257 kg) and four castrated male swamp buffaloes (Buffalo, 543 kg) were subjected to urea space measurements to determine body composition of the different animals and to investigate the effect of 48 h of water deprivation on the change of body composition in Northeast Thailand. The percentage of empty body protein (EBPRO) compared to empty body weight (EBW) was similar among Holstein, Native and Buffalo. The percentage of empty body water (EBH₂O) was the highest in Native, while the percentage of empty body fat (EBFAT) was the highest in Buffalo. After the dehydration, mean BW decreased in Holstein, Native and Buffalo, and not only water but also protein and fat were mobilized. The percentage of EBPRO was similar among Holstein, Native and Buffalo; however, the percentage of EBFAT was the highest in Buffalo and the percentage of EBH₂O was the highest in Native. After dehydration, the percentage of EBFAT decreased and the percentage of EBH₂O increased in all animals.