Effect Of Moringa Leaf Polysaccharides On Oxidative Stress And Somatic Cell Number In Milk Of Dairy Cow Mammary Gland

Dairy cows undergo extensive physiological and metabolic changes during the production process,leading to a large accumulation of reactive oxygen species,which can easily induce oxidative stress,leading to diseases such as dairy cow mastitis,resulting in higher treatment costs.Antibiotics are often used in dairy cow production to treat mastitis disease.Therefore,finding new additives to promote healthy dairy cow breeding has become a hot issue for scholars in the industry.Moringa leaf polysaccharide（MLP）can effectively scavenge active oxygen and improve the body’s antioxidant capacity,but whether it has the potential to alleviate oxidative stress in dairy cows is unclear.Therefore,this experiment takes MLP as the research object.Firstly,through the in vitro cell culture experiment,the protective effect of MLP on the oxidative damage of bovine mammary epithelial cells（BMECs）is explored,and the cow feeding experiment is used to further evaluate the MLP on dairy cows in vivo.The effects of lactation performance,antioxidant capacity and plasma immunity are expected to provide a scientific basis for the application of MLP in dairy cow production.The development of this research is of great significance for alleviating the oxidative stress of dairy cows.Experiment 1:The protective effect of MLP on oxidative damage of BMECsIn this experiment,BMECs were cultured in a medium containing gradient concentrations of H₂O₂for 2 hours,and cell viability was tested to determine the concentration of H₂O₂when establishing an oxidative damage model;cells were cultured with different concentrations of MLP solution in the cell culture medium for 2 hours to screen the dosage of MLP;the final conclusion is that the concentration of H₂O₂and MLP are 4 mg/m L of 500μmol/L,respectively.First,divide BMECs into 4 groups for treatment,control group 1（BMECs+MLP）,control group 2（BMECs）,injury group（BMECs+H₂O₂）and protection group（BMECs+MLP+H₂O₂）,and then treat different treatment groups Fluorescence intensity of reactive oxygen species,catalase（CAT）,superoxide dismutase（SOD）,glutathione peroxidase（GSH-Px）activity and the content of malondialdehyde（MDA）,is tested.The results showed that MLP can inhibit the generation of reactive oxygen species and significantly reduce the content of MDA,while significantly increasing the activities of CAT,SOD and GSH-Px（P<0.05）.The results of Hochest33258 staining and transmission electron microscopy showed that the cells protected by MLP had complete structure and regular morphology.In order to further explore the protective effect of MLP on BMECs,this experiment used Western blot and RT-q PCR to detect the protein and m RNA expression of Caspase-3,Bax and Bcl-2 in cells.The results showed that MLP can significantly reduce Caspase-The expression level of 3（P<0.05）,and reduce the ratio of Bax to Bcl-2 to slow down cell apoptosis.Experiment 2:The effect of MLP on lactation performance,antioxidant capacity and plasma immunity of dairy cowsThis trial adopts a randomized block trial design and selects 30 healthy Holstein cows with similar body condition and at the peak of lactation（weight=618±11.3 kg;lactation days=31±3.6 d;milk production=32.3±1.58 kg;Parity=2）,randomly divided into 3 treatment groups:（1）basal diet group（CON）;（2）add 50 g/d MLP treatment group（50MLP）;and（3）add 100 g/d In the MLP treatment group（100MLP）,after a 2-week adaptation period,an 8-week feeding test was carried out.The test results show that the addition of 50 g/d and 100 g/d MLP can significantly increase milk protein production and concentration,and significantly reduce the number of somatic cells in milk（P<0.05）.In addition,the addition of 50 g/d and 100 g/d MLP can significantly increase the total antioxidant capacity（T-AOC）and SOD activity in dairy cow plasma,and significantly reduce the MDA content（P<0.05）.Adding 50 g/d and 100 g/d MLP to the basal diet can significantly increase the content of Ig A and Ig M in the plasma of dairy cows（P<0.05）,and improve the immunity of dairy cows.In summary,this study draws the following conclusions:（1）MLP can improve the antioxidant capacity of dairy cow mammary epithelial cells,and protect cells from apoptosis caused by oxidative damage by inhibiting the production of ROS.（2）MLP can improve the antioxidant and immune abilities of dairy cows and reduce the number of somatic cells in the milk.