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% 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% 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.
Many shareholders attended the recent farmer consultation meetings and, as expected, there were "robust but open and inclusive" discussions in which shareholders were able to air their opinions and question the board more closely on the specifics of the proposal, Mr Morrison said.
Westland's biggest shareholder, Southern Pastures - an investment fund - has already said it would abstain on the vote to allow West Coast farmer-shareholders to decide its future.
Yili is the largest dairy producer in China and Asia and operates the Oceania Dairy plant, just north of Glenavy. The sale would also require High Court and Overseas Investment Office approvals.
Economists have said the proposed sale would create an injection of about $280million into the West Coast economy.
