The present invention relates to processes for the production of arachidonic acid containing oils, which preferably are substantially free of eicosapentaneoic acid. The invention also relates to compositions containing oils having very high amounts of arachidonic acid in triglyceride form, and to uses of such oils. In a preferred embodiment, Mortierella alpina is cultivated using conditions which yield triglyceride oil having particularly high levels of arachidonic acid residues, biomass is harvested and the oil is extracted, recovered, and used as an additive for infant formula.The present invention relates to processes for the production of arachidonic acid containing oils, which preferably are substantially free of eicosapentaneoic acid. The invention also relates to compositions containing oils having very high amounts of arachidonic acid in triglyceride form, and to uses of such oils. In a preferred embodiment, Mortierella alpina is cultivated using conditions which yield triglyceride oil having particularly high levels of arachidonic acid residues, biomass is harvested and the oil is extracted, recovered, and used as an additive for infant formula.