الكاتب: Multiple References

Vitamin D3 (cholecalciferol) has been used for many years for the prevention of milk fever in dairy cattle (Seekles et al., 1958) because it increases both the absorption of calcium and phosphorus from the diet and the mobilisation of these elements from bone. However, it acts slowly, and must therefore be administered at least 3 days before calving -- a difficult period to judge accurately, la-OH cholecaiciferol (1a-OH D3) is a readily synthesised analogue of the physiologically active metabolites of cholecaiciferol (Holick et al., 1973) which stimulates the absorption of dietary calcium more quickly than cholecalciferol itself, and thus may be more useful for the prevention or treatment of milk fever. We have studied (i) the effects of la-OHD3 on calcium, magnesium and phosphorus metabolism in dairy heifers, and (ii) its effectiveness in preventing the post-parturient hypocalcaemia and hypophosphataemia which occur normally in dairy cows.