Vitamin D Requirements of Growing Chicks as Affected by the Calcium Content of the Ration

THE vitamin D requirements of chickens has been a subject of investigation since the work of Bethke, Record, and Kennard (1) who concluded that the chick required for normal calcification 18.9 International units of vitamin D from cod liver oil per 100 grams of ration. Murphy, Hunter, and Knandel (4) reported that the chick required a minimum of 17 International units of vitamin D from cod liver oil per 100 grams of ration from hatching time till 24 weeks of age. Carver, Robertson, Brazie, Johnson, and St. John (2) found that the chick required 17 International units of vitamin D from cod liver oil per 100 grams of ration for satisfactory calcification and growth. Russell, Taylor, and Wilcox (5) reported that normal bone ash and body weight were obtained in chickens at eight weeks of age when 14.9 International units of vitamin D from cod liver oil per 100 grams . . .