A restructured management approach that has put more onus on staff is paying dividends for farm managers Isaac and Michelle Johnstone.
The big jump takes the WMP price to US$3317 a tonne, up almost 50 per cent from its mid-year trough.
The overall index gained 11.4% despite big falls in the value of some commodities.
Butter Milk Powder was down 5.4%, Rennet Casein lost 4.8% and Lactose was down 4.0%.
Other commodities to make notable gains were Skim Milk Powder (+6.5%) and Butter (+4.9%).