Praise be to Allah.
In the answer to question 95329, we stated that there is nothing wrong with castrating animals if it is done for a valid reason. This is the view of the majority of scholars.
There is no report in the Sunnah of the Prophet (blessings and peace of Allah be upon him) to indicate that he dealt with castrated animals in a particular way, or that there are particular rulings concerning them. Rather the most that can be said is that he sacrificed two castrated rams. This indicates that doing so is permissible; it is permissible to castrate animals, on the one hand, and it is permissible to offer castrated animals as an udhiyah on the other hand.
Ahmad (23348) narrated that Abu Raafi‘ said: The Messenger of Allah (blessings and peace of Allah be upon him) sacrificed two large castrated rams that were white speckled with black. Classed as saheeh by al-Albaani in al-Irwa’ (4/360).
Shaykh Ibn ‘Uthaymeen said:
It is permissible to offer a castrated animal as an udhiyah, because it is proven from the Prophet (blessings and peace of Allah be upon him) that he sacrificed two castrated rams – i.e., two animals whose testicles had been cut off. The point is that the meat of a castrated animal tastes better, so castration does not harm it in the slightest.
End quote from al-Liqa’ ash-Shahri (3/111)
As for the animal whose penis has been cut off, it is not permissible to offer it as an udhiyah, as we shall see below.
The Prophet (blessings and peace of Allah be upon him) did not always choose a castrated animal for the udhiyah; rather he would sometimes choose an intact animal that had not been castrated.
Abu Dawood (2796) and at-Tirmidhi (1496) narrated that Abu Sa‘eed said: The Messenger of Allah (blessings and peace of Allah be upon him) used to offer as an udhiyah an intact (uncastrated) horned ram, that had black markings around the eyes, the mouth and the feet. Classed as saheeh by al-Albaani.
Imam Maalik (1043) narrated from Naafi‘ that ‘Abdullah ibn ‘Umar offered an udhiyah once in Madinah. Naafi‘ said: He instructed me to buy for him a horned, intact (uncastrated) ram, then to slaughter it on the Day of al-Adha in the prayer-place of the people.
He said in an-Nihaayah (3/417):
The word (translated here as) intact refers to an animal that that can impregnate a female. He chose an intact male over a castrated male or a female because he wanted one that was of high quality and large size.
See: Tahdheeb al-Lughah by al-Azhari (5/48)
Ibn ‘Abd al-Barr (may Allah have mercy on him) said:
The intact, horned ram is the best of udhiyahs according to Maalik and most of the scholars.
End quote from al-Istidhkaar (5/220)
Some of the scholars gave preference to the castrated animal because its meat tastes better. Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:
It is permissible to offer a castrated animal as an udhiyah; some scholars even regard that as preferable to an intact animal, because its meat tastes better. However the correct view is that the intact animal is preferable from one angle, because it is physically complete, and this is given precedence over the goodness of its meat.
End quote from Fataawa Noor ‘ala ad-Darb (9/42)
Other scholars regarded both as being equal, without giving precedence to one or the other.
Ash-Shawkaani (may Allah have mercy on him) said:
The hadiths on this topic were quoted as evidence for it being recommended to offer a castrated animal as an udhiyah, but what appears to be the case is that there is no preference, because it is also proven that the Prophet (blessings and peace of Allah be upon him) offered intact animals as udhiyahs, as in the hadith of Abu Sa‘eed. So they are both the same.
End quote from Nayl al-Awtaar (5/142)
Perhaps it is most correct here to say that what is best of either type is that which is fattest, has most meat, is most physically complete and best in appearance, as it says in Ahkaam al-Udhiyah wa’dh-Dhakaah (2/229).
If the intact animal is bigger and has better-tasting meat, then it is preferable, and if the castrated animal is bigger and has better-tasting meat, then it is preferable.