Opponents of sacrifice always propose a stupid question that does God need food etc? Holy Qur’an has specifically answered this stupidity by saying that neither the blood of animal nor its meat reaches God, it is only the intentions of the person who sacrifices the animal and the person’s sincerity that reaches God.
Apart from Hajj (pilgrimage), Shia Islam also promotes sacrifices upon those who are not on pilgrimage, thus, around the world Qurbani is practiced, on the 10th, 11th and 12th day of Islamic last month Dhul Hajja. Sacrifice is essential for a pilgrim but for others it is recommended.
Shia Islam has set up conditions and requirements for Qurbaani with great details:
Only permitted animals, only animals not birds are allowed for Qurbaani,
Only domesticated animals are allowed, wild animals are not allowed for Qurbani,
Camels (both male female), Bulls, Cows, Buffaloes (both male female), Goats (both male female), Sheep (both male female) etc are animals which can be offered for sacrifice,
According to Shia Islam, the sacrificial animal should not be a personally domestic or personally pet animal,
It is narrated from 6th Shia Imam Ja’far Saadiq that the animal should be purchased after the month of Dhul Hajja has set in or started,
The female animal should not be visibly pregnant, nor should the animal have a milk feeding baby,
The male animals should not be castrated; castrated animals are recommended by Sunni but are not fit for sacrifice in Shia Islam,
Animals should not have any defects like damaged eyes, lame, broken legs, broken teeth, broken horns, cut ears, cut tails, damaged testicles or any other damages or defects,
Camels should be at least five years old,
Cows, Bulls, Buffaloes, Goats should be at least two years old (when two front lower teeth are grown out),
Sheep should be at least one year old,
After purchase highest amount of care should be given to such animals as in food, water, shelter, medicine and comfort,
Animals should not face any trauma before their slaughter, not even a knife should be shown to such animals,
Each Haaji (pilgrims) has to offer one animal, but non-pilgrims can do collective sacrifices,
Animals should be comfortably bought at sacrificial place,
No animal should be sacrificed in front (no visibility) of another animal,
Water should be given to animal before sacrifice, its drinking water is not necessary,
Animals should be lied upon swiftly and be faced to Qibla (Ka’aba, Makka),
Iron or its alloy knife should be used, knife should be very sharp and very smooth, serrated knife is prohibited,
Person who offers sacrifice, should try to slaughter the animal himself, if not then by other competent person,
Bismillaah, Allahu Akbar should be recited by the person who slaughters, the person should have niyyaah (intention) for slaughter while the recitation and slaughter,
All other animals except camels should be slaughtered (Dabiha or Zabiha) smoothly and swiftly by cutting the neck (esophagus, windpipe, jugular vein, carotid artery) from throat side; spinal cord should never be damaged during slaughter till the animal has totally died,
Camels cannot be done with Dabiha (Zabiha), Dabiha on camels make them haraam (forbidden) and vice versa, Camels are done with Nahr, a sharp knife or spearhead is used to puncture the artery in the lower neck while the animal is facing Qibla (Ka’ba, Makka),
Any further cut or damage to animals should not be done until they are totally dead by natural blood loss; blood flow should naturally stop before any other action,
Skinning or severing the head or any other action can be done only after that the animal becomes totally dead,
Meat should be divided into three parts, only one part can be used for personal consumption, the second part should be reserved for relatives, neighbors, believers etc, the whole third part should be given as charity to poor,
The person who sacrifices should eat at least a little bit from the sacrificed meat.
Above are just a brief information, detail could be had from reliable sources.
O Allah! Salutations be upon Prophet Mohammed and upon Family of Prophet Mohammed.