The Westland Co-operative Dairy Company's board is urging all shareholders to vote on or before the July 4 meeting on the co-operative's proposed sale.
In March, Westland announced it had signed a conditional agreement to sell the co-operative to a subsidiary of Mongolia Yili Industrial Group (Yili) in a deal worth $588million.
The transaction - which had the unanimous support of the board - was subject to shareholder approval and, if approval was obtained, would occur on August 1.
To be approved, it required at least 75 per cent of the votes of all shareholders who were entitled to vote and who actually voted must be in favour of the scheme, and more than 50 per cent of the votes of all shareholders entitled to vote, whether or not they actually voted, must be in favour of the scheme.
In a statement, chairman Pete Morrison said it was very important all shareholders voted, as it was a very important decision for Westland farmers.