On some quasi-identities in finite quasigroups

In this article we consider some quasi-identities in quasigroups, in particular, quasi-identities connected with parastrophic orthogonality of a quasigroup. We also research some quasi-identities in quasigroups (in loops) with one parameter $\delta$ ($\delta$-quasi-identities) which arose by the study of detecting coding systems such as check character systems in [6] (see also [5, 7]), establish equivalence of such quasi-identities, connection of some of them with orthogonality of quasigroups and give a number of examples of finite quasigroups with such $\delta$-quasi-identities.