Effects Of Compound Enzyme Preparation On Rumen Flora、Metabolism And Production Performance Of Beef Cattle

As the global population increases,meeting the demand for animal protein products has become a major issue for global food security.Nowadays,the reduction of agricultural land area leads to the shortage of feed resources,which affects the development of livestock production.How to improve the utilization rate of livestock feed has become a major problem in livestock breeding.Since the prohibition of antibiotics,adding compound enzymes to livestock and poultry diets to improve performance has been widely used in production.As a green and efficient new feed additive,enzyme preparation can improve the production performance of livestock and poultry,improve the utilization efficiency of livestock and poultry feed,reduce pollution,play an important role in fundamentally improving the production efficiency of beef cattle,and also provide a broader space for the selection of feed raw materials.Understanding the mechanism of compound enzymes on digestion,metabolism and immunity of livestock and poultry is helpful to improve the understanding of the application of compound enzymes as new additives in the production of livestock and poultry,and can also provide relevant data for the research and development and improvement of compound enzymes in the application of livestock and poultry.Therefore,in this study,60 Shannan cattle were divided into one control group(NCE)and four experimental groups(ACE).Different doses of compound enzymes were added to the diet for feeding test for 6 months.The purpose of this study was to investigate the optimal supplemental level of compound enzyme preparation in beef cattle fattening and its effects on performance,apparent digestibility,rumen microflora structure and blood-related changes of beef cattle,so as to better understand the synergistic effects of compound enzyme on host nutrition and health of rumen microbial composition,metabolism and blood-related gene expression changes of beef cattle.The results are as follows:(1)Effects of dietary supplementation with compound enzymes on apparent digestibility,serum indexes,and production performance of beef cattleCompared with NCE group,the average daily gain in ACE group was higher than that in control group.The average daily gain in ACEⅡ group was 1.44kg/d,which was significantly higher than that in NCE group(P<0.01),followed by the average daily gain in ACEⅠ group,which was 1.30kg/d,which was significantly higher than that in NCE group(P<0.05).The digestibility of dry matter,organic matter,crude protein,energy and acid detergent fiber in ACEⅡ group was significantly higher than that in NCE group(P<0.05),IVand the digestibility of neutral detergent fiber in ACEⅡ group was extremely significantly higher than that in NCE group(P< 0.01).In serum biochemical indices,the contents of alkaline phosphatase and P in ACEⅡ group were significantly higher than those in NCE group(P<0.05),and the creatinine content was extremely significantly lower than that in NCE group(P<0.01).(2)Effects of dietary supplementation with compound enzymes on rumen microflora and function in beef cattleThe addition of complex enzymes to the diet altered the composition and functional distribution of rumen microbiota in beef cattle.Compared with NCE group,the relative abundance of Fusobacterium,butyricovibrio and succinolytic bacteria in rumen of beef cattle in ACEⅡ group was significantly increased.KEGG analysis showed that there were six tertiary pathways significantly enriched in ACEⅡ group,including "biotin metabolism","peptidoglycan biosynthesis","ketone body synthesis and degradation","nitrotoluene degradation","drug metabolism cytochrome P450" and "phosphotransferase system PTS".A total of 306 genes encoding CAZyme were identified in the CAZyme database,among which the gene encoding GT2 had the highest abundance,followed by the gene encoding GH43,GH13,CE1 and GH3.Among the CAZyme coding genes involved in carbohydrate decomposition,8 were enriched in ACEⅡ group(6 GH,1 CE,1 GT)and 2 CBM were enriched in NCE group.(3)Effects of dietary supplementation with compound enzymes on rumen metabolome in beef cattleA total of 717 metabolites were identified in the rumen fluid samples of NCE group and ACEⅡ group,and 92 different metabolites were selected between the two groups(P<0.05,VIP>1).90% of the differential metabolites were up-regulated,mainly including lipid and lipid molecules,organic acids and their derivatives,organic heterocyclic compounds,nucleotides and analogues.Enrichment analysis showed that most of these differentially metabolites were related to amino acid anabolism,and some pathways were concentrated in fatty acid synthesis and cortisol synthesis and secretion.(4)Effects of dietary supplementation with compound enzymes on blood transcriptome in beef cattleA total of 1593 differentially expressed genes were identified between NCE and ACEⅡgroups,including 506 up-regulated and 1087 down-regulated genes.Enrichment analysis showed that these differentially expressed genes were mainly related to immune response function,including inflammatory response,immune response,regulatory immune system process,primary immunodeficiency,phage,African trypanosomiasis,etc.In conclusion,this study adopted metagenomic,metabolomic and transcriptome methods,and found that compound enzymes significantly changed rumen community structure and metabolic pattern of fattening cattle,enhanced autoimmune function,promoted the degradation and absorption of dietary nutrients,improved the body’s health,and promoted the improvement of production performance.