Rumen protected fats are often included in dairy cow rations in order to increase the energy density of the ration without compromising rumen function. Various studies have examined the effects of protected fats, with some studies reporting an improvement in various fertility parameters (McNamara et al., 2003). This study examined the effect of feeding protected fat (Megalac™) on production parameters, and on the reproductive performance of high-yielding Holstein-Friesian dairy cattle.