What is the ruling on zakat for sheep that did not reach the nisab for a year, then gave birth to enough offspring to reach the nisab?

"Whoever owned livestock that did not reach the nisab (definition), then it reproduced until it became nisab, then zakat (definition) is due on it, considering the hawl (one year) of the mother animals. This is the view of Malik. Shafi'i disagreed, saying: 'Offspring are not counted unless they were from his flock before the hawl and the original flock was forty or more. If the flock did not reach the nisab, then the offspring are not counted.'"