Nutritive value of sun-dried grape pomace, incorporated at a low level in complete feed for the rabbit bred under Magrebian conditions

Abstract

The nutritive value and potential use of sun-dried grape pomace (g/kg as fed: 140 of crude protein (CP), 529 of neutral detergent fi bre (NDF), 460 acid detergent fi bre , 293 acid detergent lignin) for fattening rabbits was studied by comparing 3 experimental diets containing a low but increasing incorporation rate of grape pomace (GP): 0% (control, GP0), 3% (GP3), and 6% (GP6) in substitution to the control diet (251 g NDF and 175 g CP/kg) formulated with raw materials available in the area of Tiaret (Algeria): barley, wheat bran and straw, soybean meal and faba bean. Three groups of 30 rabbits (individually caged) were fed ad libitum the three diets from weaning (35 d, mean weight 460±83 g) to 77 d of age. The dry matter digestibility was obtained from total and individual faecal collection on all animals (3 x 30), during four consecutive days each week from 42 to 77 d of age. Then, faeces from 10 rabbits per group were selected for nutrient analyses. Intake and weight gain were recorded twice a week during the whole fattening period. Incorporating 3 or 6% of GP in a low fi bre diet impaired from 35 to 77 d growth rate (-8.8% for GP3 and GP6 vs. GP0, P<0.01), feed conversion (+8.5% for GP6 vs. GP0, P<0.01), and dressing out percentage (-2.5% for GP3 and GP6 vs. GP0, P<0.001). The digestibility of organic matter was linearly reduced from 72.8 to 70.0% with the GP incorporation rate (P<0.01), while crude protein digestibility remained unaffected and averaged 78.7%. The predicted nutritive value of sun-dried GP calculated by regression was high but highly variable for digestible energy (9.33±2.01 MJ DE/Kg, raw basis), and particularly for the digestible protein content (81.8±77.2 g DCP/kg). Thus, the sun-dried whole grape pomace could be considered as an alternative fibre source for the rabbit feeding in Magrebian area.