An investigation of milking ability in three dairy breeds has shown that selection for superior productive performance would contribute little to the improvement of milking time. The heritability of both average rate of flow and milking time was reasonably high in all three breeds, however, and direct selection should result in effective improvements.
The problem of slow milking was more acute in the Danish Red breed, in which almost one cow in ten needed more than six minutes to milk out, than in the Black Pied or Danish Jersey breeds.
A comparison of the average rate of flow and milking time as criteria of selection for milking ability indicated that both measures were equally effective in the Black Pied and Jersey breeds, but that rate of flow was considerably more (40%) effective than milking time in the Danish Reds. This was largely because the heritability of milking time in this breed was only one-third that of milking rate.
It was concluded that the average rate of flow was to be preferred to milking time as a criterion of selection for milking ability in the Danish station testing programme.