Effect of inclusion of defatted grape seed meal in the diet on digestion and performance of growing rabbits.

Abstract

The digestion and nutritive value of defatted grape seed meal (DGSM) was investigated. A basal diet was formulated to meet requirements of growing rabbits. Another diet was formulated by substituting 15.2% of the basal diet with DGSM. Two hundred eight weaned 30-d-old rabbits were fed these diets, and fattening performance was recorded. Eighty animals were used to study the effect of DGSM inclusion on cecal fermentation traits and intestinal disaccharidase activity at two ages (5 and 35 d after weaning). Fecal apparent digestibility of nutrients was measured in 18 rabbits. A third diet was formulated to contain DGSM (61.3%) as the sole source of fiber and a supplement consisting of wheat flour, casein, lard, and a mixture of vitamins and minerals to avoid nutrient imbalances. This semipurified diet was used to determine cecal digestion traits, disaccharidase activity in the small intestine, fecal apparent digestibility of nutrients, and rate of passage in 70-d-old rabbits. Digestible energy and NDF and CP digestibilities of DGSM calculated by difference were 5.51 +/- 0.89 MJ/kg DM, 24.5 +/- 5.76%, and 46.8 +/- 14.9%, respectively. Inclusion of 15% of DGSM in the basal diet increased ADFI in finishing rabbits (from 9 to 15%; P < 0.05), so that DE intake increased although dietary DE concentration decreased. As a consequence, ADG increased by 3.3% in the whole fattening period (P = 0.046). The increase in ADFI was parallel to an 8% decrease in the weight of cecal contents (P = 0.059), and it was in agreement with the relatively short cecal mean retention time of DGSM (7.61 h) in the semipurified diet. Inclusion of 15% of DGSM in the basal diet did not affect (P > or = 0.20) mortality (10.1%) or cecal concentrations of VFA, NH3 N, or cecal pH either at 5 d (71.9 mM, 17.7 mM, and 5.75, respectively) or at 35 d after weaning (74.6 mM, 10.1 mM, and 5.66, respectively) but improved the sucrase activity in the ileum by 36% (P = 0.031). Digestibility of NDF of DGSM in the semipurified diet was 8.57%, which agrees with the low acidity and weight of cecal contents of animals fed this diet (6.26 and 3.63% BW, respectively). From these results, we conclude that DGSM has a relatively high DE concentration and its inclusion at moderate levels (15%) in the diet exerts a positive effect on ADFI, DE intake, and ADG with no impairment of cecal fermentation and mortality.