不同代谢葡萄糖水平对绵羊人工瘤胃发酵特性、微生物蛋白质浓度和产气参数的影响

Effects of Different Levels of Metabolic Glucose on Artificial Rumen Fermentation Characteristics,Microbial Protein Concentration and Gas Production Parameters of Sheep

本试验旨在通过人工瘤胃体外培养,研究不同代谢葡萄糖水平下的绵羊瘤胃发酵特性、微生物蛋白质浓度和产气参数。采用单因子试验设计,共设计4个代谢葡萄糖水平[125（A）、138（B）、153（C）、168 g/kg（D）]。体外试验所用瘤胃液采自4只安装有永久性瘤胃瘘管的绵羊。分别于培养0、2、4、6、8、12、24 h采集2 mL培养液用于分析。结果表明：1）8-24 h培养液pH随着代谢葡萄糖水平的提高而出现显著或极显著下降（P〈0.05或P〈0.01）;氨氮浓度在2 h时D组显著高于A组（P〈0.05）,而在6 h时A组显著高于其他3组（P〈0.05）。2）D组6h培养液细菌蛋白浓度显著高于A组（P〈0.05）;随着代谢葡萄糖水平的提高,培养液丙酸、丁酸、总挥发性脂肪酸的浓度总体呈升高趋势,乙酸/丙酸呈下降趋势。3）随着代谢葡萄糖水平的提高,理论最大产气量极显著降低（P〈0.01）,达1/2理论最大产气量的时间极显著缩短（P〈0.01）;潜在产气量无显著变化（P〉0.05）,24 h产气量和产气速率常数分别显著或极显著下降和上升（P〈0.05或P〈0.01）。结果提示,提高代谢葡萄糖水平,可以提高丙酸、总挥发性脂肪酸的浓度,同时可为绵羊提供较多的生糖前体物质。

This experiment aimed to investigate rumen fermentation characteristics, microbial protein concen-tration and gas production parameters of sheep under the different levels of metabolic glucose through the in vitro artificial rumen fermentation. A single factor experiment design with 4 metabolic glucose levels [ 125 （ A） , 138 （ B） , 153 （ C） and 168 g/kg（ D） ] was adopted. Culture medium of 2 mL was collected for analysis at 0, 2, 4, 6, 8, 12 and 24 hours, respectively. The results showed as follows：1） with the increas-ing of metabolic glucose level, the pH of culture medium was significantly decreased at 8 to 24 h （ P〈0.05 or P〈0.01）; at 2 h, the ammonia nitrogen concentration of group D was significantly higher than that of group A （ P〈0.05） , while at 6 h, the concentration of group A was significantly higher than that of the other three groups （ P〈0.05） . 2） The bacterial protein concentration at 6 h of group D was significantly higher than that of group A （ P〈0.05）; with the increasing of metabolic glucose level, the concentrations of propionic acid, bu-tyric acid and total volatile fatty acids were increased in general, while acetate/propionate was decreased. 3） With the increasing of metabolic glucose level, the theological maximum gas production and reaching time of 1/2 of the theological maximum gas production were significantly reduced （ P〈0.01）; the potential gas pro-duction has no significant change （ P〉0.05）; the 24 h gas production and the constant of gas production rate were significantly decreased and increased （ P〈0.05 or P〈0.01） , respectively. The results indicate that the in-creasing of metabolic glucose level can improve the concentrations of propionic acid and total volatile fatty acids, meanwhile, can provide more sugar precursors for the sheep.