You should be able to release captive "items" as worker "creatures" at the Ghetto Overseer workshop. This is a new feature so i'd appreciate if people can report that it's working or not (we know it works in some basic testing.) You should be able to mod it to release cattle-like creatures rather than workers, if you like, just as you say by creating new captive cattle races. This will be a bit of DFHack modding, not just basic raw-files modding, but by looking at the current implementation you can reverse engineer it without too much trouble.
I don't entirely understand the second part of your question, sorry. ("is it possible to make them work like when they are abstracted as an item?"). Items and creatures are pretty different, so, probably the answer is no.
p.s. Glad you enjoy orc mode
