"The extension of arrangements with China State Farm confirms the strength of our relationship with key partners in China and our shared confidence in the future," a2 Milk chief executive David Bortolussi said.
Bortolussi said China State Farm's support would be critical for joint success in China.
In August, a2 Milk reported a 42 per cent jump in annual net profit to $114.7 million, driven by strong growth in its infant formula business.
At the same time, the heavily cashed up a2 Milk said it intended to return capital through a $150m on-market share buyback.
Revenue in the June year grew 19.8 per cent to $1.44 billion. A2 Milk said it was on the way to reaching revenue of $2b in five years' time.
A2 Milk's buyback starts on Wednesday.
The company said last week the weaker New Zealand dollar made for a positive start to the current financial year, with first quarter sales expected to be marginally ahead of plan.