Oligosaccharides And Enzyme Complexes To Regulate Lactation Performance And Methane Emissions In Dairy Cows

With the introduction of China’s "double carbon" strategy,low carbon emission reduction has become a necessary path to accelerate the construction of ecological civilization and achieve high quality green development in China,of which reducing carbon emissions from livestock farming is the main way to create low carbon agriculture.In this experiment,methane emissions from the rumen of dairy cows were measured simultaneously using the GreenFeed system by feeding different exogenous additives to cows,with the aim of exploring the methane emission patterns of dairy cows in China,establishing "local" methane emission factors,exploring ways to reduce methane emissions from different exogenous additives,and improving energy The aim of this study was to investigate the methane emission patterns of dairy cows in China,to establish localised methane emission factors,to identify methods and approaches to reduce methane emissions and improve energy use efficiency with different exogenous additives,and to investigate the regulatory mechanisms of methane emissions using 16S amplicon sequencing.The experiment will provide technical and scientific support for the assessment of carbon emission reduction in ruminants and the development of methane reduction measures.The experiment includes the following three aspects.1.The effect of oligosaccharides and enzyme complex on the performance of cows.Forty-eight Juan cows in mid-lactation with similar physiological conditions were used in the trial,divided into four treatment groups of 12 cows each,namely the control group,the oligosaccharide added group,the enzyme complex added group and the oligosaccharide and enzyme complex added group,all fed the base diet of the TMR on the farm.The results showed that the average daily intake of cows in the three treatment groups was 18.95kg,19.12kg and 19.19kg respectively,which was significantly higher than that of the control group(P<0.01);compared with the control group,the apparent digestibility of all nutrients in the oligosaccharide and complex enzyme groups were higher than that of the control group,but the difference was not significant(P<0.05);the oligosaccharide+complex enzyme group Cows in the oligosaccharide+enzyme group produced the highest milk yield of 21.54 kg,higher than the control group at 19.75 kg,and all indicators of milk composition were better than the control group,but the difference was not significant(P>0.05).2.Effect of oligosaccharides and complex enzymes on ruminal methane emissions from dairy cows.In this study,methane emissions from different groups of cows were measured simultaneously using the GreenFeed system.The results showed that ruminal methane production in the oligosaccharide and enzyme complex groups was 409.79 g/d and 397.77 g/d respectively,both of which were significantly lower than ruminal methane emissions from control cows(P<0.05),while methane production in the oligosaccharide+enzyme complex group was not significantly different from that of control cows(P>0.05).The CO2-eq of cows in the oligosaccharide and complex enzyme groups were 9997.70 g/d and 9987.87 g/d,respectively,both lower than the control group but not significantly different(P>0.05);the rumen VFA acetic acid to propionic acid ratios of cows in the three treatment groups were 4.30,3.90 and 4.20,respectively,all lower than the control group,with the complex enzyme group significantly lower than the control group(P<0.05).Oligosaccharide had a positive effect on dairy performance and reduced ruminal methane emissions in cows,making it the best exogenous additive screened in this trial for mitigating ruminal methane emissions in ruminants.3.Effect of oligosaccharides on rumen microorganisms in dairy cows.In this study,16S amplicon sequencing analysis was performed on individuals with very high and very low methane production in the oligosaccharide and control groups.The results showed that the abundance of methanogens belonging to the phylum Archaea,Euryarchaeota,Methanobacteria,Methanobacteriales,Methanobacteriaceae and Methanobrevibacter spp.was lower in the oligo-xylose group compared to the control group;the abundance of Succiniclasticum was higher at the genus level in the oligo-xylose group,which increased the propionic acid content in the rumen;the results of functional enrichment of rumen microorganisms showed that the rumen microorganisms in the oligo-xylose group and the control group were more abundant than those in the control group.The results of the functional enrichment of rumen microorganisms in the oligo-xylose and control groups were similar,with the oligo-xylose group having slightly higher metabolic functions than the control group;the results of the LEfSe analysis showed that Actinomycetes and Actinomycetes were significantly enriched in the rumen microorganisms of the oligo-xylose group and played an important role as biomarkers for the oligo-xylose group.