Multi-mics-based Analysis Of Oregano Essential Oil On The Health Maintenance And Its Mechanism In Pingliang Red Cattle

Livestock health,belongs to the subject area of health management,is a prerequisite for high-efficient production and it is always the major scientific issues in livestock production system.There are many factors threaten livestock health,involving the livestock itself,public health and safety,nutrition,environmental health,pathogenic microorganisms and others.The technical strategy of livestock health management is developing from veterinary antibiotic intervention and vaccine immunization to the non-antibiotic,the main approach is to use the exogenous nutrients,such as organic acids,enzymes,peptides,probiotics,prebiotics,postbiotics,plant-derived phenols and ketones,etc.for regulating the health level of the intestinal micro-ecosystem or improving positive physiological function of tissue,organ and system metabolism,to further increase livestock health level and resist to diseases.Oregano essential oil(OEO)has broad-spectrum anti-bacterial,anti-oxidant and anti-stress activity because of its high thymol and carvacrol concentrations.Its health maintenance effect is remarkable when used to the pig and poultry,however,the research on ruminant livestock health maintenance is not deep enough.Pingliang Red is a beef cattle industry pillar in Gansu Province having a genetic characteristic of producing snowflake meat.It is quite influential in the national beef cattle industry.The aim of this study is to explore the effects of dietary supplementation with OEO on the health maintenance and its mechanism in Pingliang Red cattle,and to further provide theoretical and practical basis for it’s genetic resources health management and high-efficient quality production.Twenty-seven Pingliang Red steers approximately twelve-months-old having an initial body weight(BW)of 270.47 ± 16.26 kg,were randomly assigned to 1 of 3 treatments(9steers/treatment).Cattle were fed daily a basal diet supplemented with 0(Con;Control);10g/d(L;Low),or 20 g/d(H;High)oregano essential oil(OEO).The ration was formulated to meet the American Nutrient Requirements for Beef Cattle(2016).The ration composition was adjusted every month to meet the animal’s nutrient requirements for each growth stage.The experimental period was 390 d prior to harvest with 14 d for pre-adaptation.Fattening performance,slaughter performance,carcass trait and meat quality were determined,meat fatty acids,amino acids and volatile flavor compounds contents were also analyzed.Then the tissue and digested contents of rumen and cecum were collected to measured digestive enzyme activity,fermentation parameters,epithelial development and tissue barrier function,metagenomic and metabolomic techniques were used to analyze changes in microbiota composition,function and metabolites.Lastly,serum samples were collected to determine the levels of immune and inflammatory factors as well as changes in metabolites and pathways.Results were as follows:(1)The whole process stage quality fattening experiment of Pingliang Red cattle was carried out by dietary supplementation with oregano essential oil.Compared with the Con group,the fatting efficiency was increased by 15.94% and 21.74%(P<0.05),the live weight was increased by7.84% and 16.51%(P<0.05),the carcass weight was increased by 12.29%and 13.06%(P<0.05),the net meat weight was increased by 10.90% and 14.63%(P<0.05),the p H value was decreased by 4.06% and 2.71%(P<0.05),the shear force was decreased by 16.84% and 20.64%(P<0.05)in the L and H groups,respectively.The feed efficiency was increased by 18.50%,the yields of high-grade and premium cuts were increased by10.49% and 14.62% in the H group(P<0.05).(2)The whole process stage quality fattening experiment of Pingliang Red cattle was carried out by dietary supplementation with oregano essential oil.Compared with the Con group,the lower palmitic acid in the H group(P<0.05)and stearic acid in the L group(P<0.05),leading to lower saturated fatty acid(SFA)and higher poly/monounsaturated fatty acid(P/MUFA)concentrations in the L and H groups(P<0.05);Compared with the Con group,the higher α-linolenic and γ-linolenic acids concentrations in the Land H groups(P<0.05)and conjugate linoleic acid in the H group were found(P<0.05).The higher essential amino acid,flavor amino acid and total amino acid concentrations in the H group compared with the Con group(P<0.05).Besides,increasing OEO inclusion rate increased aldehyde,alcohol,and ketone concentrations,while ester concentrations were decreased(P<0.05).(3)Compared with Con group,cellulase activity and propionate concentration were increased in the L and H group,while acetate concentration decreased(P<0.05);the rumen papillae height,butyrate and valerate concentrations were increased and amylase activity was decreased in the H group(P<0.05);the β-glucosidase activity in the H group was higher compared with Con and L groups(P<0.05).The relative abundance of Parabacteroides distasonis and Bacteroides thetaiotaomicron were increased with increasing OEO inclusion rates,and they were higher in the H group compared with the Con group(P<0.05);the GH43＿17(mainly encoding xylanase)family gene abundance was increased,while GH23(mainly involved in starch and glycogen degradation)family genes abundance was decreased(P<0.05)with increasing OEO inclusion rate.Sorbic acid,aspirin,farnesene,heparin and pantetheine contents increased with increasing OEO inclusion rates(P<0.05).Metabolic pathway KEGG function was enriched in phosphatidylinositol signaling system,Fc epsilon RI signaling pathway,alpha-linolenic acid metabolism and inositol phosphate metabolism.Correlation analysis results showed that a positive correlation was observed between Parabacteroides distasonis,Bacteroides thetaiotaomicron,and β-glucosidase,cellulase and propionate.The abundance of Parabacteroides distasonis and Parabacteroides＿sp.＿CAG:409 were positively correlated with sorbic acid and farnesene.(4)Compared with the Con group,cecum digested content cellulase activity and butyrate abundance were significantly increased,while amylase and lipase activities were decreased in the H group(P<0.05);β-glucosidase activity was higher in the H group compared with the Con and L groups(P<0.05).The Claudin-1 m RNA level in the H group,ZO-1 m RNA level in the L and H groups was increased(P<0.05),while IL-1β,LPS and TNF-α levels decreased compared with the Con group(P<0.05).The higher relative abundance of Fibrobacter＿succinogenes,Bacillus＿cereus and Bacillus＿licheniformis,while lower relative abundance of Alistipes＿sp.＿CAG:157 were observed with increasing OEO inclusion rates(P<0.05).KEGG functional enrichment analysis revealed that amino sugar and nucleotide sugar metabolism pathway decreased with increasing OEO inclusion rates(P<0.05).The CAZyme functional enrichment analysis indicated that CBM4(mainly involved in xylan degradation)abundance increased,while GT94(mainly involved in xanthan gum biosynthesis)decreased with increasing OEO inclusion rates(P<0.05).The lysophospholipid and amino acid compounds in the L and H groups were increased compared with the Con group,and they were mainly enriched glycine,serine and threonine metabolism and aminoacyl-t RNA biosynthesis pathways.(5)Compared with the Con group,serum Ig G concentration was increased in the H group,while LPS concentration was decreased(P<0.05);IL-4 concentration was increased in the L and H groups;the IL-1β,IL-2,TNF-α and TNF-β concentrations were decreased with increasing OEO inclusion rates(P<0.05).α-mercholic acid,7-ketolithocholic acid,12-ketolithocholic acid,23-deoxydeoxycholic acid,γ-mercholic acid,and orthocholic acid abundances were higher in the L and H groups compared with the Con group,and they were intermediates of bile acid metabolic pathway.In conclusion,dietary supplementation with OEO increased fattening performance,slaughter performance and carcass trait,improved muscle tenderness and juiciness,provided a desirable fatty acid and amino acid composition along with rich volatile flavor compounds.Combined with metagenomic and metabolomic techniques,we found that OEO increased Parabacteroides distasonis abundance to produce more propionate and energy supplement,which further improved muscle tenderness and juiciness;OEO could increase Bacteroides thetaiotaomicron abundance to promote digestive enzyme activity to enhance digestive ability and promote animal growth.OEO enhanced cecum health level by maintaining intestinal barrier structural integrity and increasing Bacillus＿cereus and Bacillus＿licheniformis abundances;OEO promoted cecum digestive ability by increasing Fibrobacter＿succinogenes abundance and fiber digestive enzyme.OEO modulated host metabolism level by regulating host inflammatory and immune factors and bile acid metabolism in the serum.This study provided a theoretical and practical basis for the healthy and high-efficient production of Pingliang Red cattle industry to further enhance its germplasm resources utilization value.