NRBC stands for Nucleated Red Blood Cells.
absolute number of nucleated red blood cells
Yes, EDTA can lead to degeneration of nucleated red blood cells (nRBCs) in a blood sample. EDTA acts as an anticoagulant by binding to calcium ions, which can cause nRBCs to swell, rupture, and lose their distinct morphology. This degeneration can make it challenging to accurately identify nRBCs in a blood smear.
Nearly all non-mammal vertebrates have nucleated red blood cells (nRBC). Non-nucleated RBC's are a unique feature to mammals. There are of course a few notable exceptions, such as the artiodactyl order, which have an odd blood morphology.