Sampling and Testing Milk for Butterfat

Milk plant operators buy milk from dairy farmers at a price which varies according to the fat content of the milk. The per cent of fat is determined at the milk plant laboratory by an accurate method called the Babcock test. In order to save on the cost of testing milk each day, a composite or periodic sampling technique is commonly used. By these methods, only one sample is tested over a period of time, as compared to the necessity of testing a sample each delivery. A composite sample is made by taking a sample from each day's delivery and placing it in a sealed container. The daily samples from each producer are combined with the portions from the previous days. The composite sample may cover a period from five to 15 days. The per cent fat in the composite sample is applied to the total amount of milk delivered by that producer during the period.