Biological values of minerals

François Meschy

Diets are often deficient in minerals compared to animal requirements. They must be corrected either by incorporating a premix in the diet (monogastrics), or by the distribution of a mineral feed (ruminants). The choice of mineral sources - minerals or organo-metallic complexes - is therefore a very important one: efficient mineral utilisation by the animal is necessary both to satisfy its mineral requirements and to limit pollution from farm effluents (mainly phosphorus, copper and zinc). In 1999, the International Association of the European Manufacturers of Major, Trace and Specific Feed Mineral Materials (EMFEMA) commissioned in 1999 a European group of experts (G. De Groote and M. Lippens, Belgium, for poultry; A. Jongbloed, The Netherlands, for pigs and F. Meschy, France, for ruminants) to produce an up to date report on the subject (EMFEMA, 2002).

Choosing a scale of relative biological value (RBV) has allowed the integration of experimental data in addition to those on apparent and true absorption (for example, bone parameters and tissue concentrations). Publications were only included in the database if they satisfied certain conditions. Notably, the mineral source studied needed to be precisely (and if possible chemically) defined and the experimental and analytical methods had to be clearly described. The results from a total of 222 publications, irrespective of type of mineral and animal species, were used to create the database. Weighting factors were applied to take into account the pertinence and the reliability of the parameters studied. This scale could be modified depending on whether the dietary supply covered animal requirements or whether it was above requirements. In the case of measurements of tissue concentrations, log10 transformation of the values was performed for some elements (copper, zinc and selenium) to keep the RBV within physiological limits. In order to take into account the power of the experimental setups, the average values were weighted by the square root of the number of trials in the same publication. The tables indicate, for each species and for each mineral element, the number of trials, the average value and the standard deviation.

In most cases, the reference source (RBV = 100) is unique, thus enabling direct comparisons of mineral sources. The tables present only the most frequently used mineral sources in Europe. Additional information and the detailed protocol of this study are provided in the original document published by the EMFEMA (downloadable from www.emfema.org).

References

  • EMFEMA, 2002. Bioavailability of major and trace minerals. EMFEMA, Bruxelles.