Synlait Milk has cut its farmgate milk price forecast for this season to $4.20 a kg of milksolids from $5.00 a kg.
The Rakaia-based company said low international prices were behind the move, which follows Fonterra cutting its farmgate milk price forecast last week.
Synlait managing director and chief executive John Penno said things were "very tough" for dairy farmers who had gone through two years of unsustainably low milk prices.
"It's important that we continue to give our suppliers a clear and realistic idea of where the milk price is likely to end up. As always things may change, and we hope they do because it's hard to run a dairy farm business in this environment," said Penno.
Synlait chairman Graeme Milne believed that the recovery in commodity prices would be slower than anticipated.