What are the rules for animal sacrifice during Hac?

The animal sacrifice (hady) is farz (wajib) for hacilar performing Hac Tamattu (those who perform Umre, exit Ihram, then enter Ihram again for Hac) and Hac Qiran (those who combine Umre and Hac in a single Ihram). Pilgrims performing Hac Ifrad (Hac only, without Umre) are not required to offer a sacrifice, though it is sunnet.

Acceptable animals include: a sheep or goat (one per haci), a cow (shared among up to 7 hacilar), or a camel (shared among up to 7 hacilar). The animal must meet minimum age requirements — sheep must be at least 6 months old, goats 1 year, cows 2 years, and camels 5 years. The animal should be healthy and free from defects: not blind in one eye, not obviously lame, not emaciated, and not missing a significant portion of an ear or horn.

The sacrifice should ideally be performed on the 10th of Dhul Hijjah (Yawm al-Nahr — Day of Sacrifice), as part of the day's sequence: stoning, then sacrifice, then shaving/trimming, then Tavaf. However, the sacrifice may be delayed until before sunset on the 13th of Dhul Hijjah. Most hacilar today arrange their sacrifice through the Saudi Project for Utilization of Hady and Udhiyah (the official sacrifice management organization), which handles the slaughter and distributes the meat to the poor worldwide. You simply pay the fee and receive a certificate confirming the sacrifice was performed.