A method of collecting a sample of milk while milking a succession of animals comprises diverting a portion of milk from an animal into a flowpath (74, 77) leading to an extraction point (80). The flowpath (74, 77) is dimensioned such that milk flows along the flowpath as a plug occupying the whole of its cross-section and allows some of the milk from the animal to pass the extraction point (80). Thereafter the milk is transferred into a container or other receiver and at least some of the remaining milk of that animal reaching the extraction point.