应用Rusitec系统研究壳聚糖对体外瘤胃发酵特性的影响

Effects of Chitosan on Rumen Fermentation Characteristics:An in Vitro Study Using Rusitec System

本试验应用Rusitec系统研究壳聚糖对体外瘤胃发酵特性的影响。发酵体系由400 mL瘤胃液、400 mL缓冲液、70 g瘤胃内容物和20 g饲粮(装于尼龙袋内,精粗比为40∶60)组成,采用单因子完全随机设计将Rusitec系统的发酵罐分为4个处理,壳聚糖的添加量分别为0(对照组)、500、1 000、1 500 mg,每个添加量2个罐,重复进行2期试验,即每个处理4个重复,每个重复1个罐,每期预试期7 d,正试期2 d。检测甲烷产量、产气量、挥发性脂肪酸浓度及养分降解率的变化。结果表明:1)与对照组相比,500、1 000、1 500 mg组甲烷产量分别降低了17.71%、31.67%、50.37%,差异显著(P<0.05)。2)添加壳聚糖显著降低了各时间点乙酸和丁酸浓度以及乙酸/丙酸(P<0.05),显著提高了丙酸浓度(P<0.05);添加壳聚糖显著降低了总氮、氨态氮、尿素氮浓度(P<0.05),显著提高了微生物氮浓度(P<0.05)。3)1 000、1 500 mg组粗蛋白质降解率显著低于对照组(P<0.05)。4)甲烷产量,总氮、氨态氮、尿素氮、微生物氮、乙酸、丙酸和丁酸的浓度,乙酸/丙酸以及粗蛋白质降解率与壳聚糖添加量间呈显著的线性关系(P<0.05)。由此可知,壳聚糖能改变瘤胃微生物发酵模式,提高发酵液丙酸浓度,降低乙酸浓度,减少甲烷生成,提高能量利用,同时减少蛋白质在瘤胃中的降解。

This experiment was conducted to study the effects of chitosan on in vitro rumen fermentation char- acteristics using Rusitec system. The fermentation system consisted of 400 mL rumen fluid, 400 mL buffer, 70 g rumen content and 10 g diet （concentrate： roughage = 40：60 ）. Fermenters were divided into four treat- ments by a single-factor completely randomized design, and chitosan supplemental levels of the four treatments were 0 （ control group）, 500, 1 000 and I 500 mg, respectively. Two fermenters were used for each chitosan supplemental level, and the experiment consisted of two repeated trials, i. e. , and there were four replicates in each treatment and one fermenter per replicate. After a 7-day pre-trial period, fermentation parameters inclu- ding methane yield, gas production, volatile fatty acid concentration and nutrient degradation rates were deter- mined in a 2-day trial period. The results showed as follows ： 1 ） compared with control group, methane yield in 500, 1 000 and 1 500 mg groups was significantly decreased by 17.71%, 31.67% and 50.37%, respec- tively （ P 〈 O. 05 ）. 2 ） The supplementation of chitosan significantly decreased the concentrations of acetic acid and butyric acid, and acetic acid to acrylic acid ratio （ P 〈 0.05 ）, but significantly increased propionic acid concentration （P 〈 0.05 ） ; the supplementation of chitosan significantly decreased the concentrations of total nitrogen, ammonia nitrogen and urea nitrogen （ P 〈 0.05 ）, but significantly increased microbe nitrogen con- centration （P 〈 0.05 ）. 3 ） Compared with control group, crude protein degradation rate in 1 000 and 1 500 mg groups was significantly decreased （ P 〈 0.05 ）. 4 ） Methane yield, the concentrations of total nitro- gen, ammonia nitrogen, urea nitrogen, microbe nitrogen, acetic acid, propionic acid and butyric acid, acetic acid to propionic acid ratio, and crude protein degradation rate were significantly linearly correlated with chi- tosan supplemental level （P 〈 0.05）. In conclusion, chitosan can modify rumen microorganism fermentation pattern, improve propionic acid concentration in fermentation fluid, reduce acetic acid concentration and meth- ane yield, improve energy utilization, and abate degradation of protein in rumen. E Chinese Journal of Animal Nutrition, 2013, 25（8）：1851-18591