Musannaf Ibn Abi Shayba 5:122

'Abd al-Rahim ibn Sulayman narrated to us, from Zakariyya, from Abu Ishaq, from 'Asim ibn Damra, from 'Ali, who said: "When [the cattle] reach thirty, then in them is a *tabi'* (a one-year-old male calf) or a *tabi'a* (a one-year-old female calf) that has completed a year. When they reach forty, then in them is a *musinna* (a two-year-old cow) that has entered its third year, or older."