In this study, the effects of nano zinc oxid (nZnO) as a dietary zinc supplement on the population of rumen protozoa in Markhoz goat kids were investigated. A total of 12 male Markhoz goat kids aged 7-8 months were randomly allotted to 3 treatments including; 1) basal diet containing 22.12 mg Zn/kg DM; 2) basal diet+20 mg Zn/kg DM as nZnO and 3) basal diet+40 mg Zn/kg DM as nZnO in a completely randomized design. The diets were offered daily at 08:00 and 17:00 in 2 equal portions for 14 days. On the end day of the experiment, 3.5 h after morning feeding, rumen fluid was obtained from each kid via esophageal tube. The samples were tested for total count and the kind of protozoan. In the rumen fluid of the kids were found 5 kinds of protozoa (Isotricha, Dasytricha, Entodinium, Diplodinium and Epidinium spp.). No significant difference was observed between treatments for a total count of protozoan. Highest and lowest counts were found for Entodinium spp. And Isotricha spp., respectively. Overall results showed that the levels of 20 and 40 mg Zn/kg DM as nZnO had no effect on the population of rumen protozoa in Markhoz goat kids.
