Thesis - Open Access
Master of Science (MS)
For the past several years there has been a growing tendency among dairymen, particularity those located near the large cities, to keep their cows in the barn much of the time. Under such a system of management the cows receive but little direct sunshine. In some localities it is also possible to find many cows which are fed the year around on dry feed receiving very little, if any, green food, either as soiling crops or as pasture. From many standpoints such practices are, of course, necessary and desirable, but from the standpoint of the nutritional value of the milk produced there are those who question the desirability of such practices. On July 1, 1927, an experiment was begun at South Dakota State College to determine the effect of direct sunlight upon the growth and development of dairy calves. Eight grade Holstein heifer calves, all less than two weeks old, were secured for this experiment. Four of these calves were reared in a shed which opened into a large outside lot in the south. They were allowed to run in this outside lot at will and consequently received an ample supply of direct sunshine. The other four heifers were reared in the west half of a shed which had two large window in the east end. These heifers had no other source of sunshine and were not allowed outside. The eight heifers in this experiment were bred and were kept under the conditions just given until some of them had completes their first lactation period. Breeding difficulties of an undetermined nature were encountered and only one of the sunshine heifers and two of the no sunshine heifers became pregnant and freshened. A heifer calf from one of these no sunshine heifers was kept and was reared under the same no sunshine conditions which the previous no sunshine heifers had been subjected to. This second heifer (whose herd number is 104591) gave birth to a normal calf April 6, 1932, and is now near the end of her first lactation period. Her milk was used in the rat feeding trials to be discussed later. The three feeding trials reported in this paper were conducted to compare the nutritional value of the milk from these no sunshine heifers with that of milk from cows which had been allowed access to sunshine. Particular emphasis was placed upon the vitamin D content of the milk in all trials. Trials were also conducted to determine, if possible, the immediate effect of direct sunlight and pasture on the vitamin D content of milk produced by cows handled in a normal way.
Library of Congress Subject Headings
Diary cattle -- Feeding and feeds
Milk -- Composition
Includes bibliographical references (pages 100-103)
Number of Pages
South Dakota State University
Robinson, Ben L., "The Influence of Feed and Sunshine on the Vitamin D Content of Cow’s Milk" (1933). Theses and Dissertations. 1237.