Lo. Fiems et al., THE INFLUENCE OF DIETARY ENERGY AND PROTEIN-LEVELS ON PERFORMANCE, CARCASS AND MEAT QUALITY OF BELGIAN WHITE-BLUE DOUBLE-MUSCLED FINISHING BULLS, Animal Science, 66, 1998, pp. 319-327
The effect of three protein (77, 97 and 117 g DVE (true protein digest
ed in the small intestine) per kg dry matter (DM)) and two energy leve
ls (7.38 and 8.03 MJ NEF (net energy for fattening) per kg DM) on the
performance of Belgian White-blue double-muscled finishing bulls and o
n the quality of their carcasses and meat was investigated. The diet,
offered ad Libitum, consisted of 650 g/kg concentrates and 350 g/kg ma
ize silage on DM basis. No significant influence was found of the ener
gy level on the growth rate. The low protein level reduced live-weight
gain, from 370 to 501 kg (1.43 kg on average v. 1.60 and 1.66 kg dail
y; P < 0.01). The growth rate during the entire period (370 to 692 kg)
and the live weight at slaughter were significantly influenced by the
protein content. The bulls given the high energy level lost less weig
ht during the 20-h fasting period before slaughter. Their carcasses we
re classified with a higher fatness score and a better conformation. T
hese carcasses had a higher fat content, while the proportion of bone
in the carcass was lower than in the low energy groups. The cold carca
ss weight of the low protein groups (456 kg on average) was significan
tly smaller than that of the four other groups (470 kg on average). Al
though no differences between the six groups were found concerning the
dressing proportion, this measurement was significantly influenced by
the protein level (685 g/kg for low protein v. 691 for high protein).
The SEUROP conformation was positively influenced by the protein and
the energy level, while the fatness score was influenced only by the e
nergy level (5.5 v. 6.0 for the low and the high energy level, respect
ively). Although the differences in conformation, fatness score and dr
essing proportion are significant, because of the small variation, the
practical meaning is less important.