Alimentation minérale et vitaminique des ruminants : Actualisation des connaissances

Abstract

The aim of this review was to update the French dietary allowance recommendations (DAR) for minerals, trace elements and vitamins for ruminants. For phosphorus (P) and calcium (Ca) the maintenance requirement (MR) is now based on dry matter intake and body weight. For Ca, MR is higher for lactating and growing animals. For magnesium (Mg), MR is slightly increased to take into account inevitable urinary loss, underestimated to date. Productive requirements are little modified in comparison to former recommendations. New recommendations on electrolytic balance (EB, K+ + Na+ - Cl-, mEq/kg DM) of diets under production targets are proposed, thus EB < 50 in pregnancy and EB around 250 in lactation could be assessed. For trace elements, DAR remain unchanged except for that of cobalt which goes from 0.1 to 0.3 mg/kg DM for optimising cellulolytic activity of rumen bacteria. The re-assessment of DAR for A, D and E vitamins according to the latest American recommendations has led to increased levels of vitamin A and E (especially during pregnancy). Digestive efficiency of dietary mineral supply is updated by considering true availability coefficients (TAC) by groups of feedstuffs; these changes especially concern P. For Mg different values are adopted for cattle (and goats) and sheep. In addition, the negative effect of K level in the diet upon Mg absorption is quantified for different ruminant species., The methodology of the assessment of mineral and trace element content of forages and concentrates is described in the perspective of the publication of the revised edition of the tables of composition and nutritive values of ruminant feedstuffs.