Can I hear music in ogg vobis format?

No, Itunes nor ipad support this format.

iTunes 11 can currently read, write and convert between MP3, AIFF, WAV, MPEG-4, AAC and Apple Lossless (.m4a).^[34]

The current supported audio formats for the iPad (2 / 3 / 4 / mini) are:

• AAC (bitrates from 8 to 320 Kbps)
• HE-AAC (bitrates from 8 to 320 Kbps)
• Protected AAC (DRM copy protection used on the iTunes Store)
• ALAC (Apple Lossless)
• MP3 (bitrates 8 to 320 Kbps)
• MP3 VBR (Variable Bitrate)
• AA (Audible formats 2, 3, 4) / Audible Enhanced Audio / AAX / AAX+
• WAV

No. iTunes on the iPad is only a gateway to the store. It cannot play audio from your library.

Ogg is in fact a very lossy format. MP3 would be much better in most circumstances.

In any case, if you absolutely need to handle ogg files, you'll need a 3rd party player like VLC

https://itunes.apple.com/us/app/vlc-for-ios/id650377962?mt=8