Study On The Effect And Mechanism Of Chitooligosaccharide And Malic Acid To Inhibit Methane Emission

As a greenhouse gas,methane(CH4)not only causes a greenhouse effect,but also waste of energy in the synthesis of methane by ruminants.At present,reducing rumen methane production mainly through feed additives which could change the rumen fermentation type,reduces the formation of acetic acid,promotes the synthesis of propionic acid or competitively utilizes hydrogen with methane bacteria.Malic acid is an intermediate product of the tricarboxylic acid cycle,and can use hydrogen to synthesize propionic acid.Chitosan could inhibit the number of Gram-positive bacteria and reduces the production of acetic acidis because of more sensitive to Gram-positive bacteria.Chitooligosaccharides is a product of deacetylation degradation of chitosan,and many biological properties are superior to chitosan.Malic acid and chitosan ultimately reduce the synthesis of methane by changing the rumen fermentation mode.We speculate that there should be a synergistic effect between the them.Chitooligosaccharides should have a better regulation effect on rumen than chitosan.This experiment firstly explored the effect of different levels of malic acid and chitooligosaccharides on reducting rumen methane emission in vitro,and observed whether the two have synergistic effects.On this basis,we will explore the regulation of chitosan with different viscosity degree on rumen fermentation type.Provide a research basis for better and safer use of feed additives for methane emission reduction.This study consists of two parts: Experiment 1 Effects of different levels of malic acid and chitooligosaccharide on rumen methane emissionThis experiment was carried out by in vitro fermentation.Different levels of malic acid and chitooligosaccharides were added to the feed to observe the effects of them on rumen fermentation parameters.The purpose of this study was to observe the regulation effect of chitooligosaccharides on rumen and determine whether it has synergistic effect with malic acid.This experiment uses a two-factor factorial design.The malic acid is divided into four gradients of 0,4,8 and 12 mm/ml.Chitooligosaccharides are divided into 0,4,8 and 12 mg/g.A total of 16 treatments were carried out,6 replicates per treatment,and 24 hours of in vitro fermentation were performed to observe changes in rumen fermentation gas volume,CH4 production,rumen fermentation parameters.The results showed that: 1)With the increase of malic acid in the feed,the rumen methane production in vitro fermentation decreased gradually,and when the amount of malic acid added was 8 mm/ml,the methane production was the lowest.The addition of chitooligosaccharide to the feed had no significant effect on the yield of methane(P > 0.05);2)As the level of malic acid in the feed increased,the concentration of acetic acid in the rumen fluid decreased significantly(P < 0.05),the concentration of propionic acid increased significantly(P < 0.05),and the ratio of ethylene to propylene in the rumen fluid decreased significantly(P < 0.05).When the amount of malic acid added was 12 mm/ml,the concentration of acetic acid and the ratio of propionic acid to acetic acid were the lowest,and the concentration of propionic acid was the highest.The addition of chitooligosaccharides in the diet had no significant effect on the concentration of acetic acid in the rumen fluid,the concentration of propionic acid,and the ratio of propionic acid to acetic acid(P > 0.05).3)There is no synergistic effect between malic acid and chitooligosaccharides in inhibiting rumen methane emissions in vitro.In this experiment,malic acid improved the rumen fermentation mode,reduced rumen methane emissions,chitooligosaccharides did not achieve the expected results.The specific reasons need further discussion.Experiment 2 Effect of chitosan with different viscosity on rumen fermentation typeAccording to the results of experiment one,In this experiment,the artificial rumen system was used to investigate the effects of chitosan with different viscosity on rumen fermentation.The test was divided into four groups: control group,low viscosity(< 200 mPa·s),medium viscosity(200-400 mPa·s),and high viscosity(> 400 mPa·s)chitosan group,each treatment had 6 repetitions.The test was 11 days,the first 7 days were pre-test period,the sampling period was 4 days.The results show: compared with the control group,chitosan with different viscosity can significantly increase the concentration of propionate in the rumen(P < 0.05),reduce the ratio of propionic acid to acetic acid,and the effect of the low viscosity chitosan group is the most obvious.After adding chitosan for 6-8 h,the concentration of acetic acid decreased and the concentration of propionic acid increased.At 24 h,the ratio of propionic acid to acetic acid was significantly lower than that at 6 h(P < 0.05).all processing groups show this trend.This indicates that chitosan with different viscosity regulates rumen fermentation.In summary,the addition of malic acid to the feed could reduce the synthesis of acetic acid,change the fermentation mode of the rumen,and make it to the direction of propionic acid fermentation,reducing methane emissions.Chitooligosaccharides have no regulatory effect on rumen fermentation.Chitosan with different viscosity can promote the synthesis of propionic acid and change the fermentation mode of rumen.The effect of chitosan with low viscosity was the best.The chitosan starts to play for 6 h after the addition,and lasts for 24 h.Therefore,in production practice,in order to improve the production performance of ruminants,an appropriate amount of malic acid and chitosan may be added in daily amounts.