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 pre diction equations of body water, fat, protein and energy content from the l ive 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 spectr ometry. Ewes were weighed, body condition scored and then slaughtered. The body water, fat, protein, ash and energy were chemically determined. At sla ughter, ewes weighed 43.4+/-7.0 kg, and contained 26.0+/-2.6 kg of water an d 9.3+/-4.2 kg of fat. A relative lack of variation in the fat-free empty b ody (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. Bod y water was significantly correlated with SD2O. The body fat and energy con tent 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 equat ion 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 E lsevier Science B.V. All rights reserved.