Energy and protein requirements of Belgian Blue double-muscled bulls

Energy and protein requirements were determined for Belgian Blue double-mus cled (BB dm) bulls based on the results of two feeding trials and a trial w ith serial slaughtering. The results of the serial slaughter experiment all owed calculation of chemical composition and energy content of the empty bo dy, as well as protein and energy deposition at various live weights betwee n 350 and 650 kg. Protein requirements were calculated based on the protein requirements for maintenance, the protein mass accreted and the efficiency of protein accretion. Efficiency of protein deposition (g protein accretio n/g protein intake for accretion) was derived from the feeding experiments based on marginal protein levels; it decreased from 0.53 to 0.44 with incre asing live weight. Energy requirements were also derived from the same data base. Net energy for maintenance was estimated, with these animals that rec eived an optimum energy/protein ratio, by subtracting the net energy retain ed from the net energy intake. Requirements were then determined by summati on of the energy requirements for maintenance and the energy requirements f or accretion. Conclusively, energy and protein requirements were determined for BE dm bulls for live weights from 350 to 650 kg and for different grow th rates. As such, surpluses of energy and protein that BE dm animals requi re compared to other beef breeds, were quantified. (C) 2001 Elsevier Scienc e B.V. All rights reserved.