Abstract :
Yearling Boer×Spanish goat wethers (40) were used to develop and compare body composition prediction equations for mature
meat goats based on urea space (US) and body condition score (BCS). Before the experiment, one-half of the animals were managed
to have high BW and BCS (1–5, with 1 being extremely thin and 5 very fat) and the others were managed to have low BWand BCS.
During the 24-week experiment, initially fat wethers were fed to lose BW and BCS and initially thin wethers were fed to increase
BW and BCS. BCS, US, and whole body chemical composition were determined after 0, 12, and 24 weeks. Mean, minimum,
and maximum values were 42.1 (S.E. = 1.12), 24.5, and 59.0 kg for shrunk BW; 3.0 (S.E. = 0.11), 1.5, and 4.0 for BCS; 61.3
(S.E. = 1.01), 53.7, and 76.5% for water; 20.2 (S.E. = 1.11), 4.7, and 29.7% for fat; 15.6 (S.E. = 0.19), 13.3, and 18.1% for protein;
and 2.9 (S.E. = 0.062), 2.2, and 3.7% for ash, respectively. For water, fat, and ash concentrations and mass, simplest equations
explaining greatest variability (with independent variables of US, BCS, and (or) shrunk BW) based on BCS accounted for more
variation than ones based on US, although in some cases differences were not large (i.e., water and ash concentrations and mass).
Neither US nor BCS explained variability in protein concentration. Equations to predict protein mass based on shrunkBWand US or
BCS were nearly identical in R2 and the root mean square error. A 1 unit change in BCS corresponded to change in fullBWof 8.9 kg
(full BW (kg) = 17.902 + (8.9087×BCS); R2 = 0.653), fat concentration of 7.54% (%fat =−5.076 + (7.5361×BCS); R2 = 0.612),
and energy concentration of 3.01 MJ/kg (energy (MJ/kg) = 0.971 + (3.0059×BCS); R2 = 0.615). In summary, BCS may be used as
or more effectively to predict body composition of meat goats than US. The primary determinant of BCS, within the range of BCS
observed in this experiment, was body fat content.
© 2006 Elsevier B.V. All rights reserved.
