Dairy giant Fonterra has released details of a $42m investment in a new Chinese dairy farm it says will soon house 3000 cows.

Dairy prices have slipped at Fonterra's overnight online auction, with the globalDairyTrade index down 2.5 per cent.

The stock exchange's new dairy futures market launched successfully at 8am morning and one trade today would make NZX head of markets Fiona Mackenzie ecstatic.

Prices slipped 1.3 per cent at Fonterra's latest online auction of milk powder, holding near a four-month high and keeping intact one of the pillars of New Zealand's terms of trade.

Fonterra has unveiled its second highest ever farmer payout, at $6.70 per kilo of milksolid, and says profits are up 12pc.