In vivo estimation of body composition from the dilution space of deuterium oxide in fat-tailed Barbary ewes

Sixteen dry ewes of the fat-tailed Barbary breed were used to formulate prediction equations of body water, fat, protein and energy content from the live body weight (BW) and the dilution space of deuterium oxide (SD2O). Ewes were injected with 0.5 g D2O/kg BW and four blood samples collected after infusion. The D2O content of blood water was determined by infra-red spectrometry. Ewes were weighed, body condition scored and then slaughtered. The body water, fat, protein, ash and energy were chemically determined. At slaughter, ewes weighed 43.4+/-7.0 kg, and contained 26.0+/-2.6 kg of water and 9.3+/-4.2 kg of fat. A relative lack of variation in the fat-free empty body (FFEB) was confirmed in this particular breed (water percentage, 74.5+/-1.6). Adiposity (fat as percent empty BW; EBW) varied between 15.1 and 36.9%. There was a close negative relationship (R-2 = 0.96; residual standard deviation (R.S.D.)= 1.4%) between the fat and the water content of EBW. Body water was significantly correlated with SD2O. The body fat and energy content prediction equations from SD2O and BW were similar to those published in a thin-tailed ewe breed (R-2 = 0.92; R.S.D = 1.4 kg). The body fat equation prediction from body condition score and/or BW was significant (R-2 = 0.81; R.S.D. = 1.9 kg) although not as precise as that using D2O. (C) 2000 Elsevier Science B.V. All rights reserved.