Abstract: The study involved 30 local Iraqi sheep and goats (15 each) and 10 Friesian x local dry cows. Urea Space Volume (USV) was calculated from 2 collection periods of blood samples following infusion of urea at 12 (US 12 kg) and 30 (US 30 kg) min after infusion and then as a proportion of live weight (BW) or Empty Body Weight (EBW). All animals were slaughtered within 2 d of the USV trials. Sheep recorded the highest percentage (80.57%) of carcass soft tissue followed by goat (79.10%) and cattle (77.77%). Cattle bone/meat ratio was significantly lower than that of sheep or goats. Water content of cattle soft tissue was higher (74.78%) than that of sheep (64.86%) and goats (69.76%); however, fat% showed reverse percentages (15.39% for sheep and 9.025% for cattle). The pooled regression between either BW or EBW and carcass soft tissue composition was similar. Water content indicated positive slope; whereas protein and fat showed negative slope with either BW or EBW. BW or EBW effectively predicted the amount of fat and protein in the carcass soft tissue rather than their percentages when pooled data were used. Initial Plasma Urea Concentration (PUC) mean did not differ significantly among the three studied species. All correlation coefficients between urea concentration at zero time and soft tissue composition were negative and significant except that of protein% and fat%. However, positive and significant correlation coefficients between US12 and kg of water, protein, fat and ash in carcass soft tissue (ranged 0.921-0.948) were found. US expressed as kg or % to either BW or EBW after 12 min of infusion showed higher correlation and regression coefficients than that of urea concentration at zero time with reverse direction. Correlation coefficients within each species between soft tissue compositions with urea concentration at zero time were non-significant except for protein amount of goats and ash% of cattle (p<0.05). For sheep and goats, correlation coefficients using water, fat and protein of sheep only (expressed in kilograms) and US at 12 min (kg) or as percentages to BW and EBW were highly significant (p<0.01). Cattle resulted in significant correlation values (p<0.05 and p<0.01) for water% with US at 12 min as percentages to body weight or empty body weight.