Self-Selection of a High Calcium Diet by Vitamin D-Deficient Lactating Rats Increases Food Consumption and Milk Production1 ROBERT BROMMAGE AND HECTOR F. DELUCA2 Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, WI 53706 ABSTRACT Lactating and nonlactating rats, both deficient and replete in chole- calciferol, were allowed a free selection among three diets containing 0.47 % Ca, 0.3 % P (normal Ca, normal P diet); 2.0% Ca, 0.3% P (high Ca diet); and 0.47% Ca, 1.0% P (high P diet). An additional group of vitamin D-deficient lactating rats was fed only the normal Ca, normal P diet. Vitamin D-deficient rats showed a strong selection preference for the high Ca diet but avoided the high P diet, whereas cholecalciferol- replete rats consumed the normal Ca, normal P diet predominantly. Compared to the nonselecting rats, the selection of the high Ca diet by the lactating rats deficient in vitamin D resulted in an increase in plasma calcium levels, hypophosphatemia, a doubling of food consumption, a reduction in maternal body weight loss and a stimu lation of milk production as indicated by pup growth. These results demonstrate that vitamin D-deficient rats select a high Ca diet and that the decrease in milk produc tion found in vitamin D deficiency results from a decrease in food consumption and that this anorexia is at least partially dependent on the hypocalcemia normally oc curring in vitamin D deficiency. J. Nutr. 114: 1377-1385, 1984. INDEXING KEY WORDS vitamin D • lactation • dietary self-selection Several investigators recently have shown rats with the amount of food consumed by that vitamin D deficiency results in severely vitamin D-deficient rats produced a virtu- reduced growth rates in suckling rat pups ally identical inhibition of pup growth (6). (1-3). In examining the causes of this growth While the cause of the loss of appetite in retardation, we found that a maternal rather vitamin D deficiency is unknown, we thought than a neonatal defect is responsible (4), that this anorexia might be related to plasma and that vitamin D-deficient lactating rats levels of calcium and phosphorus since vary- produce only about one-fifth the normal ing dietary calcium and phosphorus levels amount of milk (5). The milk produced by has long been known to produce changes in vitamin D-deficient rats, while not identi- appetite and growth in vitamin D-deficient cal in composition to normal milk, is nutri- rats (7). In a preliminary experiment, we tionally adequate since it supports growth in observed that feeding a high calcium (1.4%) vitamin D-deficient pups when provided in sufficient quantities (5). Further investiga tions demonstrated that most if not all of the ~ © 1984 American Institute of Nutrition. Received for publication depressed milk production in vitamin D- ? November issa. deficient rats results from a loss of appetite. "rhlsworkwassuppôt^°y » ProgramProject GrantNO. AM-HSSI ........ flf" and a Postdoctoral TYaining Grant, No. AM-06374 (R. B.) from the Lactating ratS dérident in Vitamin U COn- National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases SUme Only One-third the normal amount OÕ of the National Institutes of Health and by the Harry Steenbock Research r . , . Fund of the Wisconsin Alumni Research Foundation. rOOd, and pair-feeding Vitamin D-replete 'No reprints will be available from the authors. 1377 by guest on July 12, 2011 jn.nutrition.org Downloaded from