Normal growth of dairy heifers
The Federal Office of Farm Management reports (March, 1914) that there are 21,749,651 dairy cows in the United States. Considering the average productive life to be six of seven years, it is evident that 3,000,000 to 3,500,000 heifers must be grown each year to maintain the present number of dairy cows. The Government estimate of the cost of raising each to a productive age is $61.41. It therefore is important, not only that they be economically grown, but that they make such growth as will result in greatest production at maturity. A review of literature shows that little has been done experimentally on the growth of dairy cattle. While the scientific facts of growth have been worked out with man and with laboratory animals, almost no application of these facts has been made to the development of farm animals. The basis of this thesis is a study of growth of dairy heifers from birth to first parturition. The development of animals kept under different planes of nutrition is considered and compared with that made by those fed rations which are thought to be suitable for normal growth. From this data a standard of growth is calculated showing the size a heifer should attain at any particular age.