Rapeseed meal as a partial replacement for sunflower meal in diets for growing rabbits - gastrointestinal tract response and growth performance

The influence of rapeseed meal (RSM) as a substitute of sunflower meal on physiological processes of gastrointestinal tract and growth performance of rabbits was investigated. A total of 24 New Zealand white rabbits were divided into three groups: without and with 5 and 10% addition of rapeseed meal in the diet (RSM0, RSM5 and RSM10, respectively). RSM was included at the expense of the same amount of sunflower meal in the diets. All diets had almost the same content of nutrients and metabolisable energy. The glucosinolates content in the RSM was 18.6 mu mol/g and in the RSM5 and RSM10 diets it ranged from 0.8 to 1.7 mu mol/g, respectively. After 36 days of RSM5 and RSM10 diets application, beneficial changes were observed in the caecum functioning of 76-d old rabbits, including: higher dry matter content (21.7% and 21.5% vs. 19.9% in the RSM0 group, p < 0.005), lower pH of digesta (6.77 and 6.54 vs. 6.91; significant differences between the extreme values), and lower concentration of ammonia (0.32 and 0.24 vs. 0.36 mg/g, the extreme values were significantly different at p < 0.005). In comparison with the control group, both dietary levels of RSM significantly reduced the pH of colon digesta (from 7.24 to 7.04 and 6.77) and the content of ammonia (from 0.49 to 0.40 and 0.38 mg/g, respectively). Dietary RSM had no significant influence on feed intake, rabbits growth, and feed conversion ratio. Results obtained show that the use of rapeseed meal in the diet can reduce the negative impact of sunflower on fermentation processes in the lower gastrointestinal tract of rabbits, however without increasing growth performance of animals.