S. De Campeneere et al., Evaluation of urinary creatinine excretion to estimate in vivo body composition of Belgian Blue double-muscled bulls, ANN ZOOTECH, 49(4), 2000, pp. 335-342
Urinary creatinine excretion (UCE) and chemical body composition of 18 Belg
ian Blue double-muscled bulls were determined. Paltry due to the large fast
ed live weight (fLW) range (308-710 kg), kg water and protein in the empty
body were quite accurately predicted (adjR(2) = 0.94 and 0.97) by UCE. The
precision of the prediction of kg empty body fat was less good (adjR(2) = 0
.77). However, the empty body composition of the bulls varied only slightly
and linearly with increasing live weight so that the fLW was the beat para
meter to estimate empty body water and protein with an adjR(2) Value of 0.9
9 for both. The empty body fat was estimated from fLW with an adjR(2) = 0.7
5. The equations predicting relative body composition from UCE had much sma
ller adjR2 values, varying from 0.53 for % empty body water to 0.30 for % e
mpty body protein. However, the coefficients of variation were much smaller
. The prediction of the relative composition based on UCE was always somewh
at better than based on fLW, but the improvement was not enough to justify
the work involved in determining UCE. Conclusively, due to the small compos
itional changes, UCE did not significantly improve the estimation of the bo
dy composition from fLW. From the comparison of the results with other stud
ies, it can be concluded that the double-muscled bulls have an extremely hi
gh urinary creatinine concentration, which cannot entirely be explained by
their increased protein content.