Effect of inclusion of sunflower hulls in the diet on performance, disaccharidase activity in the small intestine and caecal traits of growing rabbits

Abstract

AbstractA basal diet was formulated to meet the nutrient requirements of growing rabbits. Another diet was formulated by substituting 152 g/kg of the basal diet with sunflower hulls (SH diet). One hundred and sixty-eight weaned 30-day-old rabbits were given these diets and finishing performance was recorded. Eighty animals were used to study the effect of SH inclusion on caecal fermentation traits at two ages (5 and 35 days after weaning) and disaccharidase activity in the small intestine at 35 days after weaning. Inclusion of SH in the diet reduced growth rate by proportionately 0·056 in the first 2 weeks after weaning (P 0 ×001), but had no effect from 14 to 65 days after weaning. Accordingly, daily gain was lower by a factor of 0·035 over the whole finishing period (P 0×01). There was no effect of treatment on food intake during the 14 days after weaning, but SH inclusion tended to increase it from this time onwards ( +0·026; P = 0 ×06) and over the whole finishing period ( + 0·018; P = 0 ×09). This effect was parallel to a 0·09 proportional decrease in the weight of caecal contents (P 0 ×01) observed in animals of 2 kg live weight. Food efficiency was lower by a factor of 0·05 (P 0×001) in all the periods considered when SH was included in the diet. Mortality rate (6%) was not affected by treatment nor was caecal pH or caecal concentrations of volatile fatty acids and ammonia nitrogen either at 5 days (5×75, 72×7 mmol/l and 16×6 mmol/l, respectively) or at 35 days after weaning (5×70, 74×3 mmol/l and 9 ×7 5 mmol/l, respectively). Inclusion of SH increased sucrase specific activity at the ileum by a factor of 0·47 (P 0×01) but had no effect on maltase specific activity at the jejunum or ileum or on sucrase specific activity at the jejunum. In conclusion, SH included at moderate levels (150 g/kg) in the diet reduced accumulation of digesta in the caecum, which increased voluntary food intake but impaired growth rate and food efficiency. Inclusion of SH did not affect caecal fermentation or mortality.