The Messenger of Allah commanded me not to take any cattle until the number had reached thirty. If the number reached thirty, then a Jadh'ah calf in its second year, either male or female, was due on them, until the number reached forty. If the number reached forty. If the number reached forty, then a Musinnah was due on them." (Daif)

Sunan an-Nasa'i Book 23, Hadith 19