Nutritional evaluation of two composite linseed-based ingredients for growing rabbits

The digestible energy and protein content of two novel linseed-based ingredients were measured in growing rabbits: a high-fat extruded linseed meal cooked (ELM) and a mixture (70:30) of high-fat linseed chaff and wheat flour (LCW). Digestible energy (DE, MJ/kg of dry matter - DM) and digestible protein (DP, g/kg DM) values were obtained from regression analysis with three dietary incorporation levels of ELM or LCW: a basal diet (0%) and two diets with 8 or 16% of ELM or LCW, respectively. The regression curves were obtained from data collected in a faecal digestibility trial (n=10 rabbits per diet, 1:1 sex ratio, 42 to 46 d old) fed at two levels of inclusion (80 or 160 g/kg DM) of each ingredient in a basal diet formulated for growing rabbits (substitution method). The regression coefficients for DE (DE=10.4+0.003×ELW) and DP (DP=145.4+0.103×ELW) obtained for the ELM were significant (P<0.001). The estimated DE and DP values for the ELM were: 13.7±0.81 MJ/kg DM and 248.6±11.4 g/kg DM. The regression coefficient for DE (DE=10.4+0.011×LCW) for the LCW was significant (P<0.001), for an estimated DE content of 20.8±0.9 MJ/kg DM. The regression coefficient for DP (DP=145.6+0.011×LCW) for the LCW was not different from zero (P=0.09), giving an estimated DP of 166.9±11.3 g/kg DM. The ELM seems to be an adequate protein source for growing rabbits. The LCW appear to be an interesting composite ingredient. It provides moderate amounts of fibre fractions in addition to energy. Moreover, both ingredients contain high levels of C18:3 omega-3 fatty acids (ELM: 34.5 and LCW: 52.9 g/kg DM). These ingredients should be included up to 10% in feed formula. Based on their characteristics, these novel ingredients may improve the feed quality of growing rabbits.