Length of Calving Interval and Average Milk Yield

The term "calving interval" refers to the period from one calving to the next calving. In dairy practice the most common calving interval is in the neighborhood of one year. Two somewhat different considerations may be responsible for this practice. There may be an economic advantage in having the flush of milk production, associated with calving, occur at some particular time of the year. There may be a biological advantage in having reproduction occur with a certain frequency. This paper is concerned with the latter eonsideration.