Why is "Ty slepice jsou moje?" not accepted?
Pro překlad "Ty slepice jsou moje" je vhodnější "Those hens are mine."
Why isn't "Ty kurata jsou moje?" not accepted? (note: with proper hachek over r) - i.e. why ma rather than moje?
ta kuřata, not ty kuřata
How would you choose between using má and moje..?
In this case it is just personal preference. To me (and it may be more general), "má" sounds more formal and will be less natural for a normal converstion but perfectly natural when writing a text.
Would mojé or mojí be acceptable in spoken conversations?
So... Is "ma" in this situation (i.e. "mine" vs. "my animals") still in the accusative? Or have we surreptitiously slipped into another case?
There is no accusative in sight. The is just something is something, everything is in nominative.