Methane production by mixed ruminal cultures incubated in dual-flow fermentors
Methane production by mixed ruminal cultures incubated in dual-flow fermentors
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DOI：
10.3168/jds.s0022-0302(04)73148-3
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发表时间：
2004-01-01
影响因子：
3.5
通讯作者：
Gumpertz, ML
中科院分区：
文献类型：
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作者：
Eun, JS;Fellner, V;Gumpertz, ML
本研究评价了稀释率和料精比对瘤胃微生物产气量的影响。连续培养用于监测三种液体稀释率(3.2、6.3或12.5%/h)和三种料精比(70：30、50：50或30：70)下的甲烷产量。过滤后的瘤胃内容物被允许进行6天的饮食适应，然后进行7天的数据收集。饲料由颗粒紫花苜蓿和浓缩混合物组成，包括磨碎的玉米、豆粕和矿物质和维生素预混合物。这项实验在裂区设计中重复进行。总挥发性脂肪酸产量平均为58.0 mmol/d，不受处理的影响。醋酸盐的摩尔比例随着料精比的增加而增加。丙酸的摩尔比例在稀释率为12.5%/h时呈下降趋势，随着中、低料精比的增加而增加。当稀释率为12.5%/h时，培养体系的pH值趋于较高。根据化学计量方程计算的甲烷产量不受处理的影响。然而，基于发酵罐顶空中甲烷浓度的甲烷产量导致了处理的交互效应。化学计量方程低估了较高稀释率和高饲料饲料下的甲烷产量。总饲料发酵力在稀释率为3.2%/h时最低，稀释率越高，微生物产量越高；精料比例越高，微生物效率越高。稀释率和料精比改变了微生物对底物的分配。基于实际浓度的甲烷产量与使用最终产品外观的化学计量方法估计的值不同。
This study evaluated the effects of dilution rate and forage-to-concentrate ratio on gas production by rumen microbes. Continuous cultures were used to monitor methane production at three liquid dilution rates (3.2, 6.3, or 12.5%/h) and three forage-to-concentrate ratios ( 70: 30, 50: 50, or 30: 70). Filtered ruminal contents were allowed 6 d of adaptation to diets followed by 7 d of data collection. Forage consisted of pelleted alfalfa and the concentrate mix included ground corn, soybean meal, and a mineral and vitamin premix. The experiment was replicated in a split-plot design. Total volatile fatty acid production averaged 58.0 mmol/d and was not affected by treatment. Molar proportion of acetate increased with increasing forage-to-concentrate ratio. Molar proportion of propionate tended to decrease at dilution rate of 12.5%/ h and increased with the medium and low forage-to-concentrate ratio. Culture pH tended to be greater at a dilution rate of 12.5%/ h. Methane production that was calculated from stoichiometric equations was not affected by treatments. However, methane production based on methane concentration in fermentor headspace resulted in an interaction effect of treatments. Stoichiometric equations underestimated methane output at higher dilution rates and with high forage diets. Total diet fermentability was lowest at dilution rate of 3.2%/h. Increasing dilution rates increased microbial yield; increasing the proportion of concentrate improved microbial efficiency. Dilution rate and forage-to-concentrate ratio altered the partition of substrate by microbes. Methane production based on actual concentrations differed from values estimated using stoichiometry of end-product appearance.