Study On The Evaluation Of Lead And Cadmium Pollution In Dairy Farms And Toxicological Effects On Breast

With the continuous improvement of people’s living standards,the proportion of livestock meat and dairy products in the dietary structure of Chinese residents has been increasing.However,the per capita intake of fresh milk and dairy products still has great space for improvement.Milk and dairy products have been mentioned many times in the dietary guidance in the Dietary Guidelines for Chinese Residents(2016)and the Dietary Guidelines for the Prevention and Treatment of Pneumonia Caused by novel coronavirus(issued on February 8,2020).Dairy cows as an important dairy livestock,the main economic product secreted by the mammary gland is milk,which not only has high nutritional value,but also has good prevention and health care functions for many diseases.Therefore,the health and function of bovine mammary gland plays a vital role.The health and function of bovine mammary gland will be affected by many factors,including genetic factors,feeding management level and environmental factors.Previously,most researchers focused on improving function of bovine mammary gland by improving genetic factors.However,in recent years,environmental pollution has become an increasingly serious global problem,and the society has paid high attention to the quality and safety of milk and dairy products.Among them,heavy metal pollution of milk and dairy products has become an important form of environmental pollution,causing serious harm to human and ecological environment.Lead and cadmium are common toxic heavy metal pollutants.As pollutants from agriculture,animal husbandry and industry,lead and cadmium will be exposed in the natural environment.If mammary glands of dairy cows are damaged by harmful substances such as lead and cadmium,it may affect the milk yield and milk quality of dairy cows,leading to health problems and decline in production performance of dairy cows.Therefore,it is of great theoretical and practical significance to evaluate the pollution of lead and cadmium in dairy farms and reveal the toxicological effects on bovine mammary glands.Through field sampling analysis and laboratory model research,this study deeply evaluated the pollution level of lead and cadmium in dairy farms,clarified the toxicological effects of lead and cadmium on bovine mammary glands,in order to improve the public’s understanding of the quality and safety of dairy products,provide practical reference for formulating new prevention and control strategies,and also provide research ideas and theoretical support for the prevention and control of other harmful substances such as heavy metals.The main results of this study are as follows:1.Study on the distribution characteristics and pollution assessment of lead and cadmium in dairy farms in some areas of Jiangsu province.The spatial distribution and clustering of lead and cadmium in three dairy farms were determined by sampling the soil and feces.Based on the obtained data and the soil data of Jiangsu Province,the pollution caused by lead and cadmium in dairy farms was evaluated.Results showed that the pollution caused by lead was low,and cadmium caused moderate pollution in many areas.Based on the decision tree analysis of the pH value and organic matter content of the dairy farm soil,it was confirmed that the pH value had a very significant impact on the content of lead and cadmium in the soil.2.Study on the function of cadmium exposure in mammary gland and mammary epithelial cells.Mammary gland and mammary epithelial cells were exposed to cadmium in vivo and in vitro,and the harm and toxicological effects of cadmium exposure on mammary glands and cells were analyzed using qRT-PCR,flow cytometry,EdU proliferation detection,H&E staining,TUNEL detection,and transmission electron microscopy.It was found that cadmium exposure can cause inflammatory reactions in the mammary gland,including mammary epithelial cells,to regulate the rate of apoptosis and proliferation of mammary epithelial cells,damage the cytoplasm,and lead to oxidative stress.At the same time,through high-throughput sequencing to identify the differentially expressed miRNAs during cadmium exposure,42 miRNAs with significant differences in expression were found to serve as follow-up research directions.3.Study on the function of lead exposure and miR-146a in mammary gland and mammary epithelial cells.Through the detection of related gene expression levels and protein immunohistochemistry verification,it was found that lead exposure can cause inflammatory reactions in the breast,including mammary epithelial cells.Through H&E staining,TUNEL testing,and EdU testing,it was found that lead exposure can also regulate the apoptosis rate and proliferation ability of cells in breast gland.Transmission electron microscopy also showed that lead exposure caused significant damage to cells.Further,by sequencing and analyzing the lead induced mRNA expression profile,90 significantly differentially expressed genes,including IRAK1,were found.The functions of miR-146a and IRAK1 were verified by qRT-PCR,flow cytometry,EdU proliferation assay,H&E staining,migration assay,and protein immunohistochemistry.The functions of lead exposure,miR-146a,and IRAK1,as well as the relationship between them,were confirmed by TUNEL testing.In summary,there is exposure to lead and cadmium in selected dairy farms,and the presence of lead and cadmium has brought relatively serious pollution to some areas.The pH value can be used as a potential predictor of lead/cadmium exposure in dairy farms.Lead and cadmium exposure in dairy farms can affect the health of mammary glands.When responding to lead and cadmium exposure,mammary glands and cells can undergo severe damage.Multiple newly identified miRNAs and mRNA,including miR-146a and IRAK1,can be used as risk assessment indicators to participate in the prediction.Lead exposure can act on mammary glands and cells through miR-146a and IRAK1.The results showed that the presence of heavy metals poses a significant obstacle to the development of healthy dairy farming,and it is still necessary to improve the feeding level,strengthen environmental control of farming,and completely eliminate the environmental presence and exposure of heavy metals,including lead and cadmium.