Abstract
The changes in bone metabolism and morphology of chondrocytes in bovine Hyena disease caused by administration of vitamin AD3E premix (V-AD3E) or vitamin A (V-A) were examined. At the each age, 5 calves were used. Among them, Hyena disease was recognized in 3 calves; a calf administered a high dose of V-AD3E premix (V-A 3, 000, 000, V-D3 300, 000, and V-E 1, 200 I.U./day), a calf administered a half dose of the V-AD3E premix, and a calf administered only V-A 3, 000, 000 I.U./day. The remaining calves without Hyena disease were a calf administered only V-D3 300, 000 I.U./day and a control calf. Each agent was administered orally for 10 days from 1 week after birth. In the 3 calves with Hyena disease, the bone metabolism in bone histomorphometry of ilium was in the state of low turnover at the age of 50 days. The bone volume was small at the age of 12 months. The epiphysial growth plates of the distal femurs and the proximal tibias partially disappeared and the chondrocyte lacunas in them were flattened. The matrix fibers of epiphysial growth plates were thinner in diameter and higher in density than those of the control calf. In the calf administered only V-D3, the values of bone volume decreased with aging. In conclusion, Hyena disease may be caused by excessive administration of V-A, because hypervitaminosis A suppressed the activity of differentiation and proliferation in chondrocytes and osteoblasts, and excessive administration of V-D3 may promote these actions.
