No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

Five varieties of napiergrasses (Pennisetum purpureum) were fractionated botanically into leaf blade, leaf sheath, stem and head. Chemical composition of each of whole napiergrass and their botanical fractions were determined. Correlation, linear and multiple regressions between botanical fractions and nutritive value of varieties of napiergrass were also estimated. All botanical fractions differed due to the effect of variety. Napier Pusha contained the highest proportion of leaf blade and internode, but the lowest proportion of leaf sheath. Napier Hybrid contained the lowest proportion of leaf blade, but highest proportion of node. Consequently, napier Pusha contained the highest (p<0.01) crude protein (CP, 9.0%), but Napier Hybrid had the lowest CP (7.0%). Chemical composition of whole plant differed significantly (p<0.01; except NFE, p>0.05) due to the variety. Not only the whole plant, chemical composition of most botanical fractions of whole plant differed (p<0.05 to 0.01) due to the variety. The intrarelationships between leaf blade and leaf sheath was negative (r=-0.43). Leaf sheath was also negatively correlated to CP, but positively correlated to ash of whole Napier or their botanical fractions. Leaf blade, on the other hand, increases CP but decreases ash content of whole plant or their fractions. These results, therefore, suggest that napiergrass varieties differ widely in terms of botanical fractions and nutritive value, which may have important implications on intake and productivity of animals. Furthermore, napiergrass varieties should be selected for leaf blade only for a better response.

Converting organic waste into energy through anaerobic digestion is gaining popularity day by day. The reactor temperature is considered as one of the most vital factors for the digestion process. An experiment was conducted in the Biogas Laboratory of Green Energy Knowledge Hub at Bangladesh Agricultural University (BAU) to examine the influence of temperature on anaerobic digestion of cow-dung. Laboratory-scale continuous stirred tank reactors with a working volume of 15 L were operated for a 30-day retention time. The reactors were set at 20 °C, 25 °C, 30 °C, 35 °C, 40 °C and 45 °C, respectively to determine the effect of temperature on anaerobic digestion performance. Different parameters like total solids, volatile solids, pH, volatile fatty acids, ammonia nitrogen, total nitrogen, biogas production rate and methane concentration were examined. Among all the reactors, the reactor at 40 °C temperature produced maximum biogas (312.43 L/kg VS) and methane yields (209.70 L/kg VS), followed by the reactors at 35 °C and 30 °C, respectively. Statistical analysis of the obtained experimental results using Minitab® (State College, PA, USA) showed that the optimum process performance in terms of methane yield and volatile solid degradation is achieved at a reactor temperature of 35.82 °C.