Effects of media and promoters on different lipid peroxidation assays in stallion sperm

•Lipid peroxidation (LPO) was determined in viable stallion sperm populations.•Milk-based media protected sperm from LPO under promoter-free conditions.•Ultraviolet light promoted sperm LPO in defined and milk-based media.•The study was designed to investigate both early and late stages of sperm LPO. Effects of different media and promoters on lipid peroxidation (LPO) in viable stallion sperm have not been reported. Aims of this study were to determine effects of three media (INRA-96™, Equipro CoolGuard™, and Biggers, Whitten and Whittingham [BWW]), and promoters (iron sulfate-Fe; ultraviolet light-UV; or control-no exposure to promoters) on viable sperm LPO using four different flow cytometric assays (i.e., BODIPY, Liperfluo, 4-hydroxylnonenal [4HNE], malonaldehyde [MDA]). Significant media x promoter interactions were detected using the Liperfluo, 4HNE, and MDA assays (P