It is a tool used in dairy farming to detect mastitis, an inflammation of the mammary gland in cattle. The paddle has four separate wells, which correspond to the four quarters of a cow's udder.
It is used with a CMT reagent to perform a quick, on-farm test for subclinical mastitis.
The test involves mixing milk from each udder quarter with the reagent in the respective wells. The resulting reaction, such as a gel formation, indicates the presence of elevated somatic cell counts (SCC), which is a sign of infection.
The paddle is typically made of sturdy plastic and is reusable.