体外法研究脂多糖对瘤胃发酵的影响

本试验旨在通过体外法研究脂多糖(LPS)对瘤胃发酵的影响。选取4头健康、体况相近、安装有永久性瘤胃瘘管的荷斯坦奶牛用于瘤胃液的采集。试验分为对照组(不添加LPS)和试验组(添加LPS 100 000 EU/m L),分别在发酵2、4、8、12、24 h后取样,测定发酵液p H及挥发性脂肪酸、氨态氮、微生物蛋白浓度。结果表明:随着发酵时间的延长,对照组与试验组发酵液p H逐渐下降,发酵液总挥发性脂肪酸、氨态氮、微生物蛋白浓度及乙酸、丙酸、丁酸含量逐渐增加,对照组与试验组之间均无显著差异(P0.05),但在8、24 h试验组发酵液p H与对照组相比有降低的趋势(0.05≤P0.10),4、8、24 h试验组氨态氮浓度与对照组相比有降低的趋势(0.05≤P0.10)。结果显示,在体外发酵条件下,添加LPS具有降低发酵液p H以及氨态氮浓度的趋势,但这一影响并不显著。

Effects of Lipopolysaccharide on Rumen Fermentation Investigated by in Vitro Method

This experiment was conducted to examine the effects of lipopolysaccharide ( LPS) on rumen fer?mentation by in vitro method. Four healthy Holstein cows fitted with permanent ruminal cannulas were used as the donor of rumen fluid. Two levels of LPS 0(control group) and 100000 EU/mL (experimental group)] were supplemented in substrates of different groups. Samples were collected after being cultured for 2, 4, 8, 12 and 24 h, respectively, to determine pH and concentrations of volatile fatty acids, ammonia nitrogen and microbial protein of fermentation fluid. The results showed as follows:with the extension of fermentation time, fermentation fluid pH in control group and experimental group were gradually decreased,the concentrations of total volatile fatty acids, ammonia nitrogen and microbial protein, and contents of acetic acid, propionic acid and butyric acid were gradually increased, and compared with control group, experimental group showed no significant changes (P>0.05). Compared with control group, fermentation fluid pH in experimental group showed a downward trend at 8 and 24 h (0.05≤P<0.10), and the concentration of ammonia nitrogen showed a downward trend at 4, 8 and 24 h (0.05≤P<0.10). The results indicate that the supplementation of LPS has a tendency to decrease pH and ammonia nitrogen concentration in fermentation fluid under in vitro culture con?ditions, but the difference is not significant.