| Within the field of mastitis control in dairy cows,plant extracts are one of the most promising alternatives to antibiotics.This thesis provides theoretical data and technical support for the application of plant extracts in dairy farming by studying the effects and preliminary mechanisms of complex herbal extracts on mastitis cows.In this study,the effects of herbal extracts on the performance of dairy cows were verified by feeding tests;the effects on the immune antioxidant level and rumen bacterial community composition of cows with mastitis;and finally,the effects of herbal extracts on the mammary epithelial cells of cows with LPS-induced inflammatory damage and their regulatory mechanisms were initially investigated by in vitro culture of mammary epithelial cells.The results of the study are as follows.(1)In Experiment 1,twenty-four Holstein cows with similar litter size,lactation period,milk yield and somatic cell count higher than 500,000 cells/m L(150,100 ± 302,000 cells/m L)were randomly divided into two groups of twelve cows each.The effect of compound herbal ethanol extract on the performance of cows suffering from mastitis was studied.The results showed that the addition of compound herbal extracts made from a mixture of ethanolic extracts by honeysuckle,motherwort,forsythia and dandelion to the diet enhanced milk production(P < 0.05),improved milk quality and reduced the number of somatic cells in milk(P < 0.05)in cows with mastitis.The addition of herbal alcohol extract compound to the diet had no significant effect on the serum immunity level of mastitis cows(P>0.05).(2)In Experiment 2.1,twenty-four Holstein cows with similar litter size,lactation period and milk yield,and somatic cell count less than 500,000 cells/m L(80,600 ± 10,300cells/m L)were selected and randomly divided into two groups of 12 cows each.The effect of compound herbal water extract on the productive performance of healthy cows was studied.The results showed that the addition of complex herbal water extract to the diet had no effect on milk yield,somatic cell count in milk,apparent digestibility of nutrients and serum biochemical indexes in cows(P > 0.05),but was able to increase the content of nonfat milk solids in milk(P < 0.05).(3)In Experiment 2.2,ten transitional Holstein cows with similar body condition,lactation period,milk yield and somatic cell count(SCC)higher than 500,000 cells/m L were selected and divided into control(CON,n=5,SCC=974,800±237,500 cells/m L)and treatment(TEST,n=5,SCC=987,800±299,200 cells/m L)groups based on the principle of similar somatic cell count.Cows in both groups were not treated with drugs.The effect of the compound herbal aqueous extract on the productive performance of cows affected by mastitis was studied.The results of the study showed that the addition of compound herbal water extract to the diet significantly reduced the number of somatic cells in the milk of high somatic cows(P < 0.05),however,there was no significant effect on milk yield,milk composition,and apparent digestibility of nutrients in high somatic cows(P > 0.05).The addition of herbal water extract compound to the diet significantly increased the serum levels of Ig A,Ig M and IFN-γ in mastitis cows(P<0.05)and significantly decreased the serum levels of TNF-α(P<0.05),while it had no significant effect on the antioxidant capacity of mastitis cows(P > 0.05).The addition of herbal aqueous extract compound to the diet was able to change the β diversity of the microbial community in the rumen without affecting itsα diversity.(4)In Experiment3.1,mammary epithelial cells were induced by LPS in cows and an inflammatory damage model was established.The results showed that the inflammatory damage model of mammary epithelial cells could be successfully established when the optimal additive amount of LPS was 10 μg/ml and the optimal stimulation time was 6 h.The transcriptome sequencing analysis of mammary epithelial cells with inflammatory damage predicted that LPS induced a large amount of chemokine and inflammatory factor production(P < 0.05),mainly by stimulating NOD-like receptors,TOLL-like receptors and other signaling pathways such as NF-κB,MAPK,JAK-STAT and PI3K-Akt,which in turn caused the inflammatory damage of mammary epithelial cells in cows.(5)In Experiment 3.2,the effect of the compound herbal extracts on the mammary epithelial cells of dairy cows with LPS-induced inflammatory damage was studied by mammary epithelial cell culture technique,and the regulatory mechanism of the inflammatory response of the compound plant extracts on mammary epithelial cells was initially investigated by transcriptome sequencing.The results showed that both compound herbal extracts increased the relative value-added of mammary epithelial cells(P < 0.05),decreased the content of inflammatory factors in cells(P < 0.05)and enhanced the antioxidant capacity of cells(P < 0.05)in the inflammation model cows.The compound herbal alcohol extract inhibited the expression of p38 gene(P < 0.05)and reduced the inflammatory response of mammary epithelial cells in LPS-stimulated cows;the complex herbal aqueous extract inhibited the expression of p38,MSK and CREB simultaneously(P< 0.05),which in turn reduced the inflammatory response of mammary epithelial cells in LPS-stimulated cows. |
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