Animal board invited review: The contribution of adipose stores to milk fat: implications on optimal nutritional strategies to increase milk fat synthesis in dairy cows

•Many nutritional and non-nutritional factors affect lipid mobilization and milk fat.•Dietary starch and monensin can reduce milk fat yield independently of dietary fat.•Reductions in feed intake do not account for all milk fat losses during heat stress.•Insulin-driven reductions in adipose mobilization partly explain milk fat losses.•A multifactorial view of milk fat depression is proposed.