In vitro cecal gas production and dry matter degradability of some browse leaves in presence of enzymes from anaerobic bacterium in NZW rabbit

Abstract

This work was conducted to assess the nutritive value of four browse leaves (Acacia saligna, Atriplex halimus, Lucena leucocephala, and Eucalyptus camaldulensis) grown in the northern region of Egypt using the ceacum content obtained directly after slaughtering of 12 New Zealand White rabbits. ZADO®, enzymic preparation containing cellulases, xylanases, α-amylase and proteases from an anaerobic bacterium (patent No. 22155 of Egypt) was added at 0, 2 or 5 mg/ml of buffered caecal content. In vitro caecal gas production after 24 h of incubations (IVGP24) and dry matter degradability (IVDMD) were determined. Crude protein content of browse leaves ranged from 105 g/kg DM (A. halimus) to 221 g/kg DM (L. leucocephala). The highest ether extract (68 g/kg) was in L. leucocephala, while this species had the lowest neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin content. E. camaldulensis had the highest NDF, ADF and lignin. Total extractable phenolics (TEP), saponins (SAP) and alkaloids (ALK) contents were low in L. leucocephala and high in A. halimus and E. camaldulensis. The IVGP24, and IVDMD varied (P<0.001) among leaves, with the highest (P<0.001) value in A. halimus, intermediate in A. saligna and E. camaldulensis, and the lowest (P<0.001) in L. leucocephala. When comparing all leaves species, addition of ZADO® improved (P<0.05) caecal IVGP24, and DMD in all leaves without a significant difference (P>0.05) between the two ZADO® levels (2 or 5 mg ZADO®/ml). ZADO® increased the rate of gas production during the first 6 h of incubations. Our results suggest a positive effect of ZADO® addition on browse leaves degradation in rabbits. ZADO® could have a positive influence on the caecal microbial activity and nutrient digestion, as well as the degradation of secondary compounds of the browse leaves.