The total cow population in the 2017-18 season was 4.99million, up 2.7% 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%), the South Island accounts for 40.9% 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 331,739 kilograms of milk solids. This reflected a combination of larger herd sizes, higher stocking rates and more milk solids per cow.
In 2017-18, average production per effective hectare and production per cow were both higher in the South Island than in the North Island.
Twenty-three percent of all dairy cows were located in the Waikato region, followed by North Canterbury (14.0%), Southland (11.7%) and Taranaki (9.6%).
There were two million cows in the South Island in the 2017-18 season, North Canterbury's average herd size of 803 being the largest.
Farms in the South Island were on average larger than those in the North Island, both in terms of farm area and cow numbers.
The average herd size in both islands increased this season.
Hawke's Bay's average herd size of 664 was the largest in the North Island.
The smallest average herd sizes were in Auckland (273), Taranaki (295) and Northland (319).
South and North Canterbury had the highest average cows per hectare (3.44 and 3.43 respectively).
The regions with the lowest average cows per hectare were the West Coast (2.21) and Northland (2.28%).
Otago was home to 5.4% of the national dairy herd population, and Southland's proportion was 11.7%.
Otago had 445 herds, a total of 267,874 dairy cows, and 91,438 hectares effective.
Southland had 982 herds, a total of 583,240 cows and 221,343ha effective.
