| As an agricultural country, the development of animal husbandry occupies important position in the economy as a whole market. With the improvement of people’s living standard, the nutritional requirements for food also become higher. At present, in order to improve the milk yield of cow and satisfy the demand of the market, many farms prefer to feed cows with high concentrate diet. High concentrate diet can increase milk production in the short term, but feeding high concentrate for a long time, can cause the changes in the rumen microbial environment to cows, and the gram-negative bacteria multiply and disintegrated in large quantities because of the action of bacteria autolytic enzyme, release the lipopolysaccharide (LPS). LPS is the component of gram-negative bacteria cell wall, when it freed from the cell wall, the toxicity will increase dramatically. LPS went into the blood stream by digestive tract, causing systemic inflammatory response. And as one of the major organs of the body’s digestive metabolism, the liver is very vulnerable to LPS, once the liver was damaged, the other tissues and organs will be affected. This experiment was divided into three parts, research on the damage mechanism of liver from LPS.1. High concentrate diet effects on liver functionSix adult holstein cow were divided into two groups randomly, one group was fed with high concentrate diet as experimental group, the other was fed with lower concentrate diet as control group. Blood sample of jugular vein was collected in each cow, and the plasma was separated by the centrifugal immediately, the liver function was determined with the automatic dry biochemical analyzer, the results were analysed with SPSS software. Conclusion:albumin and total protein concentration in the peripheral blood group of the high concentrate was significantly lower than low concentrate, the activity of GOT, GPT and LDH were significantly higher than that of low concentrate group, suggesting that protein synthesis function of liver in high concentrate cows was reduced, liver cells were damaged, making the intracellular enzyme released and went into the peripheral blood, warning the liver function was affected.2. The determination of concentration of LPS in portal and hepatic vein.Each cow was fixed with the portal vein and hepatic vein vascular tube after four months, so the samples can be collected by any times, and the nutrients digestion of liver could be analysed. The fat polysaccharide content in the portal and hepatic plasma were determined with limulus reagent, the datas were still analysed with the SPSS. Conclusion:The content of LPS in experimental group was much higher than control group, and the content of LPS in hepatic vein was lower than that of portal vein. We can see that LPS went into the liver from the rumen, but after the removal of the liver function, the concentration significantly decreased at the time of out the liver, alleviating inflammatory injury of the body.3. The effect of endogenous LPS to the expression of inflammatory factors on the liver of dairy cows.Liver samples were collected on the surgery, part of the samples were fixed with the paraformaldehyde, and the tissue section were made with HE staining; the other part were saved into -70℃ for RN A extraction, and the mRNA expression of several important inflammatory factors through inflammatory pathways mediated by TLR4in the liver were determined with real-time PCR (qRT-PCR) method, datas were analysed by SPSS. Conclusion:liver tissue appears obvious pathology change in high concentrate group of dairy cattle, mainly in the necrosis of liver cells, the crushing and dissolved of nucleus, inflammatory cells infiltration, etc.; the expression of the inflammatory factors in liver of high concentrate group is higher than low concentrate group, including TRAF6, IL-1 and NF-κB significantly increased. Suggesting that, in high concentrate cows, inflammatory pathways were activated in the body, causing inflammation reaction. |
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