It is desirable and usual for suppliers to hold share capital in proportion to the amount of produce supplied. Earlier, shares had to be held in proportion to cows milked. This, however, was unfair to the man with the low-producing herd, who had to take up a disproportionate share of capital; it was also unfair to the man with the high-producing herd, who did not receive his full interest payments. At present shares are allotted on the basis of butterfat supplied (all payments to suppliers are made on this basis). The precise relation varies among companies from one share to 50 lb of butterfat a year to one share for 300 lb of butterfat. One 1 share to 80 lb of butterfat is probably the most common. The directors usually have power to allot shares without reference to the shareholder. Shares are paid up either by a deduction of d. to d. per pound of butterfat supplied monthly or by a similar deduction annually from the deferred payment made after the product of the factory has been sold. Cooperative dairy companies are administered by a directorate elected by the shareholders. Large companies comprising many factories have ward systems of election so that the directorate can represent the whole area.

Dairy companies vary greatly in size. In 1959–60, of 92 dairy companies producing butter, 14 produced less than 249 tons, and one, over 10,000 tons. Most produced between 1,000 and 5,000 tons. Of 101 cheese companies, 18 produced under 149 tons, and three, over 5,000 tons. Nineteen factories produced under 1,000 tons. Most produced between 150 and 750 tons, for, as cheesemaking uses whole milk, it developed in smaller units, drawing supplies from limited areas to suit the once primitive transport facilities. In contrast, butter production use cream, only a tenth of the bulk of whole milk; this is more conveniently carted, so that a greater area can be served by one factory. Recently, smaller companies have tended to group themselves into larger units, with considerable economic advantage. The New Zealand Cooperative Dairy Co. illustrates successful amalgamation. The company was formed by the amalgamation in 1920 of three large dairying concerns in the Waikato, New Zealand's greatest dairying district. The company has since then gained enormously. It runs 39 factories, many of which can make milk powder and casein, as well as butter. In 1959–60 the company produced 75 679 tons of butter and 50,296 tons of milk powder (37 and 60 per cent respectively of New Zealand's total production), as well as much cheese and casein.

Whole milk, instead of cream alone, has recently been collected by tanker. This enables factories to make milk powder and casein, an important addition to export earnings.