Hypophosphatemia induced by dietary aluminium hydroxide supplementation in pigs: effects on growth, blood variables, organ weights and renal morphology

Twenty-four pigs, 13-14 weeks of age, were studied during an experimental period of 10 weeks. The pigs were randomly divided into 3 groups. Two groups were fed a commercial feed supplemented either with a suspension of aluminium hydroxide (Al(OH) 3 ) or aluminium phosphate (A1PO 4 ). The third group served as a control. The same total amount of aluminium was given to each of the 2 experimental groups. After three weeks the Al(OH) 3 -pigs developed severe hypophosphatemia, with an average decrease in serum phosphate of 60%, a decreased growth rate and a lower concentration of 2,3-diphosphoglycerate in the erythrocytes as compared to controls. Intense hypercalcemia developed in the Al(OH) 3 -group during the first 6 weeks, whereas the AlPO 4 -pigs and the control group developed neither hypophosphatemia nor hypercalcemia. At necropsy, the consequence of the long lasting hypophosphatemia was found to be increased relative kidney weights with morphological signs of tubular damage and dyscalcification. No similar changes were observed in the AlPO 4 -groups and there were no organ weight deviations compared to the control group.