Rumen microbiome structure and metabolites activity in dairy cows with clinical and subclinical mastitis

Background:Due to the high prevalence and complex etiology,bovine mastitis(BM)is one of the most important diseases to compromise dairy cow health and milk quality.The shift in milk compositions has been widely investigated during mastitis,but recent studies suggested that gastrointestinal microorganism also has a crucial effect on the inflammation of other peripheral tissues and organs,including the mammary gland.However,research focused on the variation of rumen inner-environment during mastitis is still limited.Therefore,the ruminal microbial profiles,metabolites,and milk compositions in cows with different udder health conditions were compared in the present study.Furthermore,the correlations between udder health status and ruminal conditions were investigated.Based on the somatic cell counts(SCC),California mastitis test(CMT)parameters and clinical symptoms of mastitis,60 lactating Holstein dairy cows with similar body conditions(excepted for the udder health condition)were randomly divided into 3 groups(n=20 per group)including the healthy(H)group,the subclinical mastitis(SM)group and the clinical mastitis(CM)group.Lactation performance and rumen fermentation parameters were recorded.And rumen microbiota and metabolites were also analyzed via 16S rRNA amplicon sequencing and untargeted metabolomics,respectively.Results:As the degree of mastitis increased,rumen lactic acid(LA)(P<0.01),acetate,propionate,butyrate,valerate(P<0.001),and total volatile fatty acids(TVFAs)(P<0.01)concentrations were significantly decreased.In the rumen of CM cows,the significantly increased bacteria related to intestinal and oral inflammation,such as Lachnospiraceae(FDR-adjusted P=0.039),Moraxella(FDR-adjusted P=0.011)and Neisseriaceae(FDR-adjusted P=0.036),etc.,were accompanied by a significant increase in 12-oxo-20-dihydroxy-leukotriene B4(FDR-adjusted P=5.97×10^(−9))and 10beta-hydroxy-6beta-isobutyrylfuranoeremophilane(FDR-adjusted P=3.88×10^(−10)).Meanwhile,in the rumen of SM cows,the Ruminiclostridium_9(FDR-adjusted P=0.042)and Enterorhabdus(FDR-adjusted P=0.043)were increased along with increasing methenamine(FDR-adjusted P=6.95×10^(−6)),5-hydroxymethyl-2-furancarboxaldehyde(5-HMF)(FDR-adjusted P=2.02×10^(−6))and 6-methoxymellein(FDR-adjusted P=2.57×10^(−5)).The short-chain fatty acids(SCFAs)-producing bacteria and probiotics in rumen,including Prevoterotoella_1(FDRadjusted P=0.045)and Bifidobacterium(FDR-adjusted P=0.035),etc.,were significantly reduced,with decreasing 2-phenylbutyric acid(2-PBA)(FDR-adjusted P=4.37×10^(−6)).Conclusion:The results indicated that there was a significant shift in the ruminal microflora and metabolites associated with inflammation and immune responses during CM.Moreover,in the rumen of cows affected by SM,the relative abundance of several opportunistic pathogens and the level of metabolites which could produce antibacterial compounds or had a competitive inhibitory effect were all increased.

Nutritional value, bioactivity, and application potential of Jerusalem artichoke(Helianthus tuberosus L.) as a neotype feed resource

The large-scale development of herbivorous animal husbandry in China has increased the demand for forage products.However,due to scarce land resources and poor soil quality,forage is in short supply.In particular,high-quality forage in China heavily relies on imports.The contradiction between supply and demand for forage grass products is increasingly notable.Therefore,the development of indigenous new forage resources with a strong ecological adaptability and a high nutritional value is a key to solving this problem.Jerusalem artichoke(JA,Helianthus tuberosus L.),a perennial herb of the genus Helianthus,has advantageous growth traits such as resistance to salinity,barrenness,drought,cold,and disease.The contents of crude protein,crude fiber,and calcium in the optimal harvest period of forage-type JA straw are comparable to those of alfalfa hay at the full bloom stage and the straw of ryegrass and corn at the mature stage.Inulin in JA tubers is a functional ingredient that has prebiotic effects in the gastrointestinal tract of monogastric animals and young ruminants.In addition,some bioactive substances(e.g.flavonoids,phenolic acids,sesquiterpenes,polysaccharides,and amino acids)in JA leaves and flowers have antibacterial,anti-inflammatory,and antioxidant functions as well as toxicities to cancer cells.These functional ingredients may provide effective alternatives to antibiotics used in livestock production.In this review,we summarized the potentials of JA as a feed ingredient from the aspects of nutritional value and fermenting characteristics of the straw,the functions of physiological regulation and disease prevention of inulin in the tubers,and bioactive substances in the leaves and flowers.