There has been growing public concern with regard to the effects of heavy metals excreted by animals on the environment. Heavy metals can be lost from manure and slurry to ground and surface waters, and subsequently affect water quality (Van Horn et al., 1996). In regions of high domestic livestock production, farmers are therefore seeking means to reduce the quantity of heavy metals excreted by animals and subsequently onto the land (Van Horn et al., 1996). The objective of this study was to establish the effect of two levels of dietary Zn inclusion in two different forms (organically chelated vs. inorganic) on apparent absorption and retention in dairy cattle.