The minimum age of animals that can be sacrificed:

There is Hadith in Sahih Muslim in this context:

It is narrated on the authority of Hadhrat Jabir (May Allah be well pleased with him), he says:  The Holy Prophet (Sallallahu alaihi wa sallam) said:  Slaughter a 1-year-old goat, a 2-year-old cow and 5-year-old camel.  However, if it is difficult for you, then you may slaughter a 6-month-old sheep.

(Sahih Muslim, Vol. 2, Pg. No. 1963)

In the light of this Hadith, the jurists have opined that the minimum age of a goat is one year, of a cow 2 years and for a camel 5 years.  Slaughtering animals less than these ages is not correct.  If a sheep is fat enough that it seems to be of one year, then it is correct to slaughter it.  If the age of animals is more than what is specified, then it is all the more better.  If the age of animals is less than what has been specified, then their sacrifice is not correct.  As mentioned in Fatawa A’alamgiri:

(Fatawa A’alamgiri, Vol. 5, Pg. No. 297)

Author: Mufti Hafidh Syed Ziauddin Naqshbandi Qadri,
Professor, Islamic Law, Jamia Nizamia.