New Zealand's average dairy herd size has tripled in the past 30 seasons on the back of dairy expansion in the South Island, DairyNZ figures show.
The total cow population in the 2017-18 season was 4.99 million, up 2.7 per cent on the previous season.
Average dairy farm size also increased in the season, to 151ha effective.
Although the North Island is home to the majority of dairy herds (72.3 per cent), the South Island accounts for 40.9 per cent of all cows milked.
South Island herds had higher production than North Island herds on average, North Canterbury's average herd production being the highest at 331,739kg of milk solids. This reflected a combination of larger herd sizes, higher stocking rates and more milk solids per cow.