Enables 3-hydroxyacyl-CoA dehydrogenase activity. Involved in positive regulation of cold-induced thermogenesis and regulation of insulin secretion. Located in mitochondrion. Is expressed in several structures, including alimentary system; brain; genitourinary system; respiratory system; and sensory organ. Human ortholog(s) of this gene implicated in familial hyperinsulinemic hypoglycemia 4. Orthologous to human HADH (hydroxyacyl-CoA dehydrogenase). [provided by Alliance of Genome Resources, Apr 2022]