I recently received an email asking whether a castrated animal can be used for Eid sacrifice or not and the answer is yes, a castrated animal can be used base on the evidence that the Holiest Prophet himself observe Eid sacrifice with two castrated rams.
Animals free of all defects are those allowed for the sacrifice. As far as castration is concerned, an animal who has been castrated is not considered a defect animal, so the sacrifice of such an animal is perfectly valid. In fact, the sacrifice of such an animal is even preferred. The Holy Prophet (Sallallahu Alayhi wa Sallam) sacrificed castrated goats.
It was narrated from ‘Aishah and Abu Hurairah that when the Messenger of Allah (ﷺ) wanted to offer a sacrifice, he brought two large, fat, horned, black-and-white, castrated rams. He slaughtered one on behalf of his nation, for whoever testified to Allah with monotheism and that he had conveyed (the Message), and he slaughtered the other on behalf of Muhammad and the family of Muhammad (ﷺ).
Other Rules on the type of animals for Eid sacrifice
The sacrificed animal should be from the livestock (cows, camels, sheep, and goats).
The sheep and goats are the best animals for the sacrifice because the Prophet never slaughtered on the ‘Eed any sacrifices except these kinds of animals. But the camels, the cows, and the Buffaloes could all be slaughtered as ‘Eed sacrifices.
The ‘Eid sacrifice should be in a good state and fat enough so that its meat could be eaten as this is a symbol of Allah. And Allah Says: (And whosoever honours the symbols of Allah, then it is truly from the piety of the heart) [Quran 22:32]
The ‘Eid sacrifice should be more than six months old if it is a sheep as narrated by Ibn Majah “Only a Jaza’a of sheep can suffice as ‘Eid sacrifice” and the Jaza’a is the sheep that is at least six months old. As for ‘Eid sacrifice from the goats, it should be at least one year old. The cow, if chosen to be ‘Eed sacrifice, two years old. But the camel should not be less than five years old”.
One should also avoid making a sacrifice with a defective animal. Al-Baraa’ Ibn ‘Aazib said the Prophet stood before us and said: “Four (kinds of animals) are not sufficient in the sacrifices: The one-eyed, whose loss of one eye is evident, and the sick whose sickness is evident, the limp whose limpness is evident and the skinny one which has no flesh on it”. [al-Bukhari]
The majority of scholars are agreed that the four defects that are mentioned in the previous Hadith could be taken as a reference for other kinds of defects. So, any defect that is equal to one of them or worse than it makes the sacrifice invalid like (the blind or one which lacks one foot).