In Jain Dharma, animals should not be kept, harmed, or used for a wedding feast.

A Jain wedding should follow ahimsa and daya, so:

• no slaughter of animals,
• no meat, fish, or eggs,
• no violence for food,
• and no celebration that causes suffering to living beings.

If you mean why animals are sometimes seen at feasts in other traditions or in history, that is due to non-Jain customs. In Jainism, such practice is not accepted.

A Jain wedding is meant to be pure, peaceful, vegetarian, and compassionate.