Bacteria in milk only come from three sources, the environment, dirty milking equipment and the cow if she has clinical mastitis. Bacteria grow quickly in warm conditions. They do not grow in the bulk tank if kept at 4ºC. You want low levels of bacteria in milk to protect milk quality. High numbers of bacteria and high temperatures cause milk to go sour quickly and fail the alcohol test. This milk is then rejected. TBC measures the number of bacteria in bulk milk. TBC testing is carried out by some of the dairy processors. You want low numbers of bacteria so that the quality of the milk is high and that there wil be a long shelf life. Milk clean, dry teats with clean hands. Stainless steel milking equipment should be used, cleaned and disinfected after every milking. Milk should not be kept in plastic churns. Milk from each quarter should be checked before every milking. Mastitis milk must not be consumed or sold. Take your milk as quickly as possible after milking to the milk collection centre.