Effects of dietary aluminum on chicks Gallus gallus domesticus with different dietary intake of calcium and phosphorus.

Birds that feed in acidified areas may be exposed to an increased intake of aluminum, while their intake of calcium and phosphorus may simultaneously be low. In particular, juvenile birds foraging in acidified areas may suffer from increased effects of aluminum due to high demands of calcium. Day old chicks were fed six different diets where aluminum was combined with normal and low concentrations of dietary calcium and phosphorus for 14 days. The normal calcium-available phosphorus (Ca-P) level was 1.05%-0.45%, and the low dietary Ca-P level was 0.49%-0.21%. Aluminum was given in dietary levels of 0%, 0.13%, and 0.31%. Aluminum had no effects on growth, mortality, or hematocrit, but induced hypocalcemia. Bones accumulated more aluminum than kidneys. A high dietary concentration of aluminum (0.31%) increased the accumulation of aluminum twofold in bones and threefold in kidneys when the dietary concentration of calcium and phosphorus was halved. Opposed to the predictions, bone mineralisation was stimulated by an intermediate increase in dietary aluminum (0.13%) at both levels of dietary calcium and phosphorus. Bone stiffness was also stimulated at this dietary aluminum concentration, but only at the diet low in calcium and phosphorus. A high dietary aluminum concentration did not have any effect on bone stiffness or calcium concentration. Bone stiffness correlated positively with the calcium concentration in bone, and negatively with the aluminum concentration in bone. The effect of dietary aluminum on bone stiffness is probably caused by an alteration in bone mineralization, rather than by the presence of aluminum in bones.