We study investment decisions in a farmers' cooperative. Farmers sell their products through the cooperative. Before production takes place the cooperative has to decide on an investment. We study whether voting on investment leads to efficient investment decisions. The answer depends on how the number of votes and the cost of the investment are distributed among the farmers. It is shown that in a variety of settings, there is no reason to suppose that voting rules favoring large farmers - "one cow, one vote" rules - are more efficient than simple majority rule