Effect of substitution of sugarbeet pulp for barley in diets for finishing rabbits on growth performance and on energy and nitrogen efficiency.

One hundred forty New Zealand White x California weanling rabbits were used to study the influence of increasing dietary contents of digestible fiber replacing nonstructural carbohydrates on feed efficiency and growth performance. Four diets, formulated by replacing sugarbeet pulp (SBP) for barley grain, and two slaughter weights (2 or 2.5 kg) were used in a 4 x 2 factorial arrangement. Inclusion of 15% SBP decreased dietary energy and CP digestibilities by 6% (P < .001), but nonsignificant effects were found on growth performance, empty body composition, and DE and digestible CP efficiencies for growth. Higher levels of SBP (35 and 50%) led to leaner animals and did not affect DE intake but greatly impaired (P < .001) DE and nitrogen efficiencies, NEg intake, growth rate, and dressing percentage in relation to the control diet. Inclusion of SBP increased the weight of gut contents (P < .001) and decreased cecal pH (P < .001), with no significant effect on mortality. Slaughter weight did not affect growth rate or energy efficiency but impaired (by 13%, P < .001) feed conversion rate. Higher (P < .001) energy content in live weight gain (12.5%) and dressing percentage (3.2%) were observed for rabbits slaughtered at 2.5 kg than for those slaughtered at 2 kg. Our data indicate that SBP can replace 15% of barley grain without decreasing growth performance, although energy and nitrogen efficiencies were impaired by 5%.