Mitigation Of Rumen Methane Production By Supplementation Combination Of Ionophores Monensin And Vegetable Oils In Goats

The global ecosystem has been greatly destroyed,which is becoming a big threat for the living of our human beings,since the large amount of greenhouse gases emission.Greenhouse gases emission from livestock is one of the major sources of global greenhouse gases emission,and methane(CH4)emission from ruminant is a major source of GHG from livestock.Thus,the study of the mechanism of methane emission from ruminant and then control the emission of ruminant are of important practical significance.This study focused on the inhibitory effects of monensin and vegetable oils in CH4 emission in goats.Three parts are included in this study.The effects of monensin on goat rumen fermentation were studied in the first part:goat rumen fluid was collected before afternoon feeding,and 0,3 mg/L,6 mg/L,9 mg/L and 12 mg/L of monensin were used in in vitro fermentations for 24 h in vitro;and the rumen CH4 production,ruminal pH,total volatile fatty acid production and the concentration of each constituent,ammonia-N concentration,as well as in vitro dry matter and organic matter digestibilities and other indicators as parameters.The effects of combination of monensin and vegetable oil on the rumen fermentation of goats were studied in the second part:goat rumen fluid was collected before afternoon feeding,6 mg/L monensin and 6 mg/L oils(coconut oil,peanut oil,soybean oil,sunflower oil,canola oil and linseed oil)were respectively mixed on in vitro fermentation bottles for 24 hours fermentation;and the CH4 production,concentration of ammonia-N and volatile fatty acid,and the digestibility of dry matter and organic matter and other indicators as parameters.The third part is animal experiment:after a lot of trials in long time,the mask for taking breath air of goats was invented(patent number:201520979295.1),the animal feeding experiment was designed according to the results of the in vitro experiment,thus the combination monensin and sunflower oil which is the optimal combination was selected.The feeding experiment was the orthogonal design,and both the addition concentrations for monensin are 0,33,66mg/kg DM and sunflower oil are 0,33,66 g/kg DM.After every period of experiment,the breath air of goats were collected using the invented instrument and CH4 concentration was determined,the rumen fluid and blood were also taken for the detection of fermentation parameters and biochemistry parameters respectively,the average daily gain,the digestibility of nutrient and feed efficiency were determined during the whole experiment.The results of the three parts above were as follow:The result of the first part showed that the supplementation of monensin significantly reduced the production of CH4 in the rumen(P<0.05)compared with the control group,which reduced the production of CH4 by 63.75%.The supplementation of monensinlinearly decreased the CH4 production.The addition of monensin could significantly decrease the content of NH3-N,the total VFA and acetate production,and significantly increase the production of propionate in the rumen,thus decreased the ratio of propionate to acetate(A:P)(P<0.05).Besides,IVDMD and IVOMD were also significantly decreased.In addition,the addition of monensin did not affect ruminal pH and microbial protein production in vitro.The result of the second part showed that the combination supplementation of monensin and vegetable oil significantly reduced the number of rumen protozoa,total CH4 production(P<0.05),and decreased the rumen CH4 production by 48.58%.The supplementation of monensin and vegetable oil in the other treatments significantly reduced the NH3-N content,the total VFA production and the acetate production in vitro,(P<0.05),and the ratio of propionate to acetate(A:P)decreased significantly(P<0.05),except the monensin and linseed oil group.The addition of monensin and vegetable oils had no significant effect on ruminal pH,IVDMD and IVOMD.The best combination of monensin and sunflower oil could be selected as in vivo test additive combination since comprehensively compared including the rumen fermentation and the effect of reducing the CH4 production with other groups.The results of animal experiment indicate that the combination of monensin and sunflower oil significantly decreased CH4 production in goat rumen(P<0.05).Compared with the other experimental groups,the addition of 66 mg/kg DM monensin and 66 g/kg DM sunflower oil(M66S66 group)were the most optimal effect to reduce the number of protozoa in gastrointestinal tract,which can reduce the CH4 emission from 8.47 to 43.20%,and the CH4 emission reduction after DMI calibration is 21.50%to 51.46%.M66S66 group compared with the control group can reduce the number of ruminal protozoa 29.27 to 80.49%,the effect is most obvious.The reduction in the number of protozoa in the experiment is directly proportional to the reduction in CH4 emissions.In addition,the M66S66 group had no adverse effects on feed intake,daily gain,rumen fermentation and serum metabolites.Taking all above into consideration,monensin can significantly reduce the number of rumen protozoa,protozoa and some methanogens for the symbiotic relationship between the numbers of protozoa to reduce the number of rumen methane production may be one of the reasons.Sunflower oil can effectively reduce CH4 emission in goat rumen and increasing propionate production may compete with methanogenic bacteria to consume the substrate H2 needed by CH4 formation,thus reducing the methane production.The addition of monensin and vegetable oil had significant effects on the inhibition of rumen CH4 emission in goats.The combined use of monensin and vegetable oil could significantly reduce rumen methane emissions and had no adverse effect on animal growth performance.