The South Island dairy herd grew by 13% between 2008 and last year.
Figures from the annual agricultural production survey show the herd increased 10% in Canterbury and 19% in Southland.
The South Island expansion increased the national dairy herd to a new record of almost six million cattle.
In contrast, sheep numbers have continued to fall, estimated at less than 32.5 million last year, down 1.7 million on the previous year.
That's less than half the sheep population in 1982 when numbers peaked at 70 million.
Deer numbers also fell by more than 1 million, but beef cattle numbers were stable at about 4 million.
The survey also showed continued growth in wine and kiwifruit production. The area planted in wine grapes increased 13% in two years, mostly in Marlborough.