Choline attenuates heat stress-induced oxidative injury and apoptosis in bovine mammary epithelial cells by modulating PERK/Nrf-2 signaling pathway

•Choline treatment has protective effect on heat stress-induced apoptosis in MAC-T cells.•Choline treatment inhibits heat stress-induced apoptosis in MAC-T cells by regulating endoplasmic reticulum stress pathway.•PERK/Nrf-2 signaling pathway may play an important role in inhibition of choline on heat stress-induced oxidative stress by choline in MAC-T cells.