The influence of heavily fertilized grass on mineral metabolism of dairy cows

Abstract

SUMMARYGroups of lactating dairy cows were fed on grass which had received various amounts of nitrogen and potash fertilizers. In the early part of the season not only was the herbage concentration of calcium and phosphorus lower in grass which had received potash fertilizer but in addition the ‘availability’ of the calcium to cows was depressed. Grass which had received large amounts of nitrogen fertilizer had a comparatively low dry-matter content in the autumn. Cows fed such grass were in negative balance for calcium at this time. As expected high dietary potassium gave rise to high excretion of potassium in the urine which in turn was correlated with high excretion of magnesium. These various factors are likely to affect the incidence of metabolic disease.