Recent developments of dietary phosphorus recommendations.

摘要

Recent reassessments of dietary phosphorus (P) supply for ruminants have been published in France as well as in other countries, (USA, The Netherlands, Nordic Countries, etc.). All converge to a decrease by about 15% of dietary P supply. After a brief reminder of their basis, this article comments on the main consequences of the application of these dietary allowances (DA) that must allow a substantial decrease of P in animal wastes. A decrease of DA associated with differences in P rumen release among feedstuffs update the studies on microbial P requirements. The recent available data do not show any important modification in the metabolism of rumen bacteria related to P supply under normal conditions of saliva production. Special attention must be paid to the assessment of the real P supply by the diet, essentially by its forage fraction. In fact, a decrease of DA associated with an overestimation of P supply could lead to a situation of P deficiency. The strategy of mineral supplementation of the rations must be the same as previously. The formula and quantity to feed the animals remain based on the mineral insufficiencies of the diet. Some oversimplification of these practices (e.g. half quantities of the complement given before with the same concentration in other components) must be discarded because of the risk of a markedly unbalanced supply of other minerals and vitamins. In order to reduce pollutant load with respect to animal performances and health, these new DA must be adopted in a rational way..