Our long term goal is to decrease the incidence and severity of periparturient disease in dairy cows through dietary modification/supplementation to improve lipid metabolism and immune system function. High density lipoproteins (HDL) are recognized to have potent immunomodulatory functions in people, particularly in metabolic diseases. Our data show that HDL regulate neutrophil function in dairy cows and perhaps more importantly HDL become dysfunctional and decrease in concentration near parturition. Our global hypothesis is that dietary supplementation can improve the composition and function of HDL in a manner that reduces the deleterious effects of inflammation. The polyphenol curcumin, derived from the turmeric plant, increases HDL and improves its anti-inflammatory function in a number of species. In this study, we will test the hypotheses: 1) supplementation of the pre-partum diet with curcumin will increase HDL concentration and improve HDL’s antioxidant and immunomodulatory properties; 2) the magnitude of the inflammatory response to intramammary bacterial Escherichia coli (E.coli) challenge will negatively correlate with HDL anti-inflammatory function. Our research team is the first toinvestigate the biological activity of bovine HDL. By pairing mechanistic assessment of HDL function with dietary interventions to increase the content and immunomodulatory quality of the HDL particle, we will lay the foundation for large scale interventional studies to use HDL as means to decrease disease incidence and severity in transition dairy cows. This is relevant to the goals of the AFRI, which include improvement of animal health and productivity through the expansion of knowledge and improvement of management practices.