In Jainism, curd is generally not considered fully suitable for strict observance, especially after sunset and during certain fasting or vow practices.

Key points:

• Curd is a dairy product, so it is not a non-violent food in the strictest sense if one follows very rigorous Jain discipline.
• Many Jains avoid curd at night because it is considered more likely to support subtle life forms and is not preferred in strict dietary restraint.
• In simple household practice, some Jains may consume curd, but strict Jain monks, nuns, and many observant laypeople avoid it, especially during vrat, upvas, or after dusk.

So, the short answer is: curd is not ideal in strict Jain practice, and many Jains avoid it, especially at night.