添加不同比例的亚油酸和亚麻酸对体外瘤胃发酵和甲烷生成的影响

利用人工瘤胃体外产气法研究添加亚油酸与亚麻酸不同比例混合物对瘤胃发酵和甲烷生成的影响。试验共设8个处理,亚油酸与亚麻酸的比例为0∶0、10∶0、8∶2、6∶4、5∶5、4∶6、2∶8和0∶10 ,每个处理设3个重复。亚油酸与亚麻酸混合物的添加水平为发酵底物干物质的5 %,未添加脂肪酸组为对照。结果表明,所有组合均显著降低产气量和甲烷生成量(P<0 .05) ,且随着亚麻酸比例的升高效果增强。亚麻酸比例超过40 %时显著升高发酵液的pH(P<0 .05) ,所有处理对氨态氮和微生物蛋白均未产生影响;总挥发性脂肪酸随着亚麻酸比例的提高而升高,亚麻酸单独添加显著高于亚油酸单独添加(P<0 .05)。随着亚麻酸比例的升高,丙酸比例显著提高。由本研究结果可知,不饱和脂肪酸降低甲烷的生成与不饱和度密切相关。

Effects of Adding Mixtures of Linoleic Acid and Linolenic Acid with Different Proportions on Rumen Fermentation and Methanogenesis in vitro

This study was carried out to investigate the effects of mixtures of linoleic acid and linolenic acid with different pro-portions on rumen fermentation and methanogenesis by using gas production function of artificial rumen.Linoleic acid and were added into tubes at a level of 5% DM of substrates.A non-supplemented substratc tube was employed as the control.The 24 h gas production and methanogenesis were significantly reduced with the addition of any mixture (P<0.05).The more the linolenic acid added,the more the decrease was.The pH of the fermentation fluid were significantly increased (P<0.05),when the proportion of Linolenic acid was more than 40%.All treatments had no significant effect on NH3-N pro-duction and microbial mass.The total volatile fatty acids increased with the increasing ratio of linolenic acid,being signifi-cantly higher with the addition of linolenic acid alone than linoleic acid alone (P<0.05).The fermentation pattern was also changed,being reflected by lower proportion of acetate and higher proportion of propionate with the increasing ratio of lin-olenic acid (P<0.05).It is inferred that reduction of methanogenesis is associated with the degree of unsaturation of C18 fatty acids.