The Progeny Test as a Method of Evaluating the Dairy Sire.

A survey of some environmental and physiological factors influencing milk yield and an analysis of theories of and experiments on milk and butterfat inheritance have been made. Further evidence is given of the fact that the proved dairy sire is the outstanding medium through which improvement in dairy cattle breeding may be effected. The need of (1) prolonging the breeding life of such an animal and (2) evolving a scheme for the regular progeny-recording of all dairy sires is emphasised. The minimum number of unselected daughters necessary to give a reasonably accurate indication of their sire's transmitting ability is six.