Composite milk samples from each farm are tested for milk fat at regular intervals, usually twice monthly. These are made up of the samples taken by the tank truck driver. Special samples are taken at frequent intervals for other quality tests. The farmer is notified if the quality of his milk supply is below acceptable levels, so he may correct the cause immediately. Regular reports on each farmer's milk supply are filed with the government department responsible for enforcing quality regulations.
Most farmers keep records of the amount and quality of milk produced by each cow.
This information is used for selective breeding and upgrading the herd. A beam of infrared light is passed through a very thin film of the milk sample as it flows through a special electric cell. Each milk component absorbs a specific amount of infrared energy at a specific wave length. By electronics, the instrument reads and transposes the amounts of absorbed energy into milk fat, protein and lactose percentages. Direct connection with a computer provides readings in less than one minute.