&i&In Vitro&/i& Digestibility and Gas Production from &i&E. crus-pavonis&/i& Used in Wetlands from Domestic Wastewater Treatment

摘要

In order to evaluate the possibilities of valorization as the feed of the plant biomass produced during wastewater treatment in constructed wetlands, a study of the in vitro digestibility and gas production of Echinochloa crus-pavonis was carried out in the Laboratory of Animal Production and Nutrition of the University of Dschang. The in vitro digestibility of Echinochloa crus-pavonis was evaluated at different harvesting periods. The digestibility parameters of E . crus-pavonis samples were determined by the in vitro method at different phenological stages. The gas production (GP) during 24 h of incubation was assessed using the in vitro incubation technique with bovine rumen fluid. In vitro dry matter digestibility (IVDM) values ranged from 52.09% to 64.76% with a decrease observed with the phenological stages of E . crus-pavonis ( from 64.76% at the leafy stage to 52.09% at the flowering stage). The microbial biomass (MB) values varied significantly between 67.99 and 88.45 mg, with no significant difference observed between the leafy (88.45 mg), bolting (82.93 mg), and early heading (80.26 mg) stages (P > 0.05). On the other hand, changes in the gas produced during 24 h from the studied samples of E . crus-pavonis (34.9 and 48 ml/500mg) and volatile fatty acids (VFA) values (1.08 and 0.80 mmol/ml) decreased significantly (P < 0.05) with the change in the phenological stage. The values of the partitioning factors (CF) of E . crus-pavonis in rumen fluid significantly decreased with advanced plant maturity (P < 0.05). The numerical values ranged from 0.52 to 1.19 ml/mg. A decrease in NDF-N was observed with the phenological stages of E . crus-pavonis . By combining the requirements of an optimal quantitative and qualitative production of E . crus-pavonis , harvesting at the bolting or early heading stage is an option of choice for exploitation as forage, under the conditions of this study. Based on the in vitro digestibility parameters studied, E . crus-pavonis is suitable as a ruminant feed.