Antirachitic Activity of Some Dehydrated Alfalfa Hays and the Effect of Adding Limestone to the Grain Ration on the Development of Rickets in Calves

Abstract

Summary The antirachitic potency of three dehydrated alfalfas has been studied with young dairy calves where the hay supplied the only source of the vitamin. The hay was fed to the calves at the rate of 1.5 lb. per hundredweight. Data on blood levels of calcium, inorganic phosphorus and phosphatase, ulna epiphyseal cartilage width obtained by periodic x-ray examinations, rate of growth, terminal rib ash content and the appearance of visible and post mortem signs of rickets were used to evaluate the rachitic condition of all calves in the experiment. One dehydrated hay supplying the calf with about 150 I.U. of vitamin D per 100 lb. of body weight was adequate when the grain ration contained added limestone, while one hay supplying 84 I.U. per 100 lb. body weight did not prevent the development of clinical rickets. The other hay provided less than 64 I.U. per 100 lb. and allowed visible and clinical rachitic symptoms to develop. Apparently, alfalfa cut at an early stage of maturity and then dehydrated probably will not itself supply a sufficient amount of vitamin D to prevent rickets in young calves. By comparing 0 and 4 per cent limestone in the grain mixture, which about doubled the calcium intake, it was shown that added calcium had a definite but limited alleviating action on the development of rachitic conditions in calves.