Phosphorus in transition cows: A dairy cow trial on phosphorus metabolism in the transition period

The present study evaluates the effect of different dietary phosphorus (P) levels in dairy cattle during the transition period, focussing on animal performance and animal health. Overfeeding P in the dry period (185% vs. 100% of requirements) did not affect feed intake or milk yield postpartum, but decreased plasma P and Ca concentrations and increased the risk for periparturient hypocalcemia. A reduction of the dietary P content in lactation diets (70% vs. 100%) reduced the average plasma P concentration, increased plasma Ca concentration and P mobilisation and reduced faecal excretion of P. However, no negative effects on cow performance or animal health were found for diets with a P content below calculated requirements in the first eight weeks postpartum.