Fiqh-us-Sunnah Volume 003, Zakaat and Fasting, Fiqh 3.041.

Section : Zakah on Cattle.

Cattle are subject to zakah provided they are a freely grazing herd and number thirty at the completion of the hawl. At that point, the zakah due is a young bull or a young cow (tabi' or tabi'ah). When they reach forty, the zakah is a young cow two years old (musinnah); when sixty, two young cows or two one-year-olds (tabi'ahs); when seventy, the zakah due is one musinnah and one tabi'; when eighty, two musinnahs; when ninety, three tabi's; when one hundred, one musinnah and two tabi's; when 110, two musinnahs and two tabi's; and when 120, three musinnahs or four tabi's. This system is followed on all additional cattle - one tabi', and on every forty, one musinnah.