By applying non-equilibrium Green's functions (NEGF) in combination with tight-binding (TB) model, the electronic transport properties of pristine and defected zigzag alpha-graphyne nanotubes (Z-alpha-GYNTs) are studied under finite bias. We have considered single vacancy (SV) and double vacancy (DV) and also the effect of tube size. Depending on the position of absent atom(s), different modes arise. Initially the formation energy is calculated for each mode and we observed that in all cases an endothermic process in needed. Moreover by studying the band structure we found that all defects cause gap closing, but not enough to change the semiconducting nature of Z-alpha-GYNTs entirely. Considering p as a positive integer, I-V characteristics show that for (3p-1, 0) tubes, all defects are found to increase the current but on the contrary presence of them in a (3p, 0) tube results in current reduction. (3p + 1, 0) tubes does not show a defined and specific reaction to the defects. Band structure of electrodes, transmission spectrum, Density of states, molecular energy spectrum and molecular projected self-consistent Hamiltonian (MPSH) are analyzed subsequently to make the electronic transport properties of GYNT devices clearer. Our results can be used in developing nano-scale devices.