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

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.

Growth Characteristics of <i>Fuirena umbellata</i>in a Surface Flow Constructed Wetland and Its Influence in Nutrients and Faecal Bacteria Removal from Domestic Wastewater in Cameroon

Various configurations of vegetated bed systems with a variety of macrophytes have been tested experimentally in Cameroon, for the treatment of domestic wastewater. The aim of this work was to assess the growth and biomass production of Fuirena umbellata (Cyperaceae) and its potentials in the removal of faecal bacteria and nutrients from primarily treated domestic effluent. A wetland vegetated with this macrophyte and a non-vegetated wetland (control) were continuously fed with primarily treated domestic wastewater at an estimated loading rate of 205 Litres/day in dry and rainy seasons for two consecutive years. Physicochemical and microbiological parameters of the effluent were monitored at the inflow and outflows of the wetlands alongside with the growth and productivity attributes of the young plants during each season. The density of plants ranged in the wetland from 17 - 185 plants/m2 and from 11 - 146 plants/m2 respectively during the first and the second years. More biomasses were instead produced in the dry seasons than in the rainy seasons but with no significant differences observed. As for nutrients removal, higher efficiencies were observed in the vegetated wetland (45% - 73%) compared to the non-vegetated control (17% - 66%). Similar trends were observed for the faecal bacteria but with no significant differences between the seasons. However, the vegetated beds were significantly more efficient than the non-vegetated control in the reduction of many physicochemical parameters and faecal bacteria. This varied with the seasons.

Effect of Added Quantity of the <i>Callistemon viminalis</i>Essential Oil on the <i>in Vivo</i>Digestibility of <i>Pennisetum clandestinum</i>Hay and Some Biochemical Parameters on the West African Dwarf Goat

The study of the effect of added quantity of the essential oil of Callistemon viminalis on the in vivo digestibility of Pennisetum clandestinum and some biochemical parameters on the West African Dwarf goat was conducted with nine old West African Dwarf goats. After the adaptation period, each animal received 900 and 100 g/day of Pennisetum clandestinum hay and concentrate respectively, associated with 0, 100 or 200 mg essential oil/kg of DM. The samples of 100 g of each ration, faeces and 10 ml of urine were collected and analyzed for chemical composition and the evaluation of ingestion and digestibility. Also blood samples were obtained from jugular vein of all goats after in vivo digestibility test for the dosage of biochemical parameters. The results of this study show that the ingestion of dry matter, organic matter and the fibers were significantly (p 0.05) higher on the goat with the ration FPc + HECv200. The digestibilities of these same components were equally higher with the ration FPc + HECv200 (71.00% and 69.00% respectively for the dry matter (DM) and organic matter (OM)). Retained (5.64 g/j) and digested (51.33) nitrogen were significantly (p 0.05) higher with the ration FPc + HECv200. The values of blood metabolites studied increased significantly (p 0.05) with added quantity of essential oil in the rations, except for albumin, globulin, glucose and the low-density lipoprotein (LDL). In general, the incorporation of essential oils of Callistemon viminalis in the ration improved ingestion, digestibility and biochemical parameters on the West African Dwarf goat.