Ammonium chloride in the prophylaxis of parturient hypocalcaemia.

Twenty Holstein X Friesian cows weighing 642 +/- 29 kg, were used at the 4th or 5th calving. They received a daily ration offering them 80 g calcium, 80 g inorganic phosphate and 60 g magnesium. Ten of these animals were supplemented with NH4Cl (20 g per animal per day, from the 15th day before calving until the 5th day after calving). This treatment had no significant effect on blood pH, ionised calcium, total calcium, inorganic phosphate, magnesium and protein levels. Among control and treated animals, three and four cows, respectively, were afflicted with parturient hypocalcaemia. These results demonstrate that in our experimental conditions NH4Cl was completely ineffective in preventing parturient hypocalcaemia.