SOIL-PLANT-ANIMAL AXIS IN GRASS TETANY

The etilogies, diagnosis and prevention of grass tetany are reviewed i n the present paper. Grass tetany is observed in cattle mainly in Spri ng and generally when grass growth is rapid after a period of cold rai ny weather. It is characterized by a reduction of magnesium concentrat ion in blood plasma. There are many causes consisting in a lack of sup ply, utilization or transfer of magnesium, different causes being invo lved simultaneously to induce grass tetany. A daily supply of magnesiu m in the diet is necessary in order to maintain magnesium homeostasia in the animal, grass composition being a factor of importance in appea rence of grass tetany. The soil-plant-animal axis has to be taken into account since grass composition is depending both from the plant and the soil in which it is growing. The management of pasture is also det erminant on grass composition. At the animal level, it is possible to explain the conditions of grass tetany from the mecanisms of magnesium absorption and its metabolism. In order to prevent grass tetany the c auses which could induce the decrease of plasma magnesium have to be c onsidered as a whole, both at the soil-plant-animal axis and the manag ement of the animal at grass. An adequate use of fertilizer according to yield and soil composition allows the production of grass in which the chemical composition is in accordance with good supply and good as similation. It is also possible to offer a magnesium supply to the ani mals in order to increase magnesium in the diet. Finally, it is sugges ted to supply feedstuffs high in energy and salt.