The increase in national dairy cow numbers has been welcomed by Waitaki MP Jacqui Dean - but it has come with a sobering reminder.
"Growth in dairy cow numbers is positive for the sector and the country but the country cannot sustain dairying at all costs," she said.
"Farmers need to take care with their environmental commitments to ensure the country can sustain the growth.
"Dairying is hugely important for our region but it cannot come at a cost to the environment and everyone in the sector needs to be mindful of this."
Mrs Dean said Fonterra and DairyNZ have worked with farmers to ensure dairying is sustainable and environmentally-friendly but it was important for the dairy industry that farmers are seen to be taking their responsibilities seriously and doing what they can to protect the land and waterways.
"We all know that dairy farmers get a bad rap and often feel that they are under siege, but as cow numbers increase - now is the time for the sector to do its best to maintain a positive, clean and green image," she said.
New Zealand's national cow herd has surpassed six million and Otago's herd has increased by 17 per cent (46,000 cows) to 308,000 last year, according to Statistics New Zealand.
The trend to dairying over sheep farming continues with overall dairy cattle numbers up by 259,000 to 6.17 million and sheep numbers falling from 32.5 million to 31.1 million.
The South Island now makes up 31 per cent of the country's entire dairy herd.