Apparent digestibility of Mediterranean forages determined by total collection of faeces and acid-insoluble ash as internal marker

The characteristics of the Mediterranean forages used in Italy could determine some differences between their energy values and the data of other similar forages listed in the table values of INRA; an accurate determination of at least organic matter digestibility must be performed. For the determination of apparent digestibility coefficients, the total collection method, that is the reference method in the French system, could be replaced by the more easy internal markers method using acid insoluble ash (AIA). In this study we determined the apparent digestibility rates of some Mediterranean forages using both total collection of faeces and acid-insoluble ash (AIA) as internal marker. The digestibility coefficients, obtained by the AIA method and the total collection method are in the same range as those listed in the INRA tables: for the organic matter, the values obtained by the AIA method range from 42.4 to 62.2%, while those obtained by total collection range from 44.8 to 58.0%. The values obtained by the two methods are comparable, as shown also by regression equations, except for the coefficients obtained for crude protein, which are the most variable. For digestibility coefficients fast assessments, the AIA method can be considered suitable, but for the introduction of Mediterranean forages in the French nutritive value tables of feeds for horses the total collection method must be considered the correct choice. (C) 2003 Elsevier B.V. All rights reserved.