[en] Inert markers are routinely used in research to estimate nutrient retention and apparent metabolisable energy nitrogen-corrected (AMEn) content of poultry diets. Acid insoluble ash (AIA) is used as a marker to substitute metal compounds because of environmental concerns. In the current research, two methodologies recommended for determining AIA content in feeds and excretas for the evaluation of total tract apparent retention (TTAR) of nutrients, were compared in 12 broiler diets. The experimental design was completely randomised with 2 AIA analytical techniques and 12 dietary treatments that resulted from a combination of two cereals (corn and rice), two heat processing of the cereal (raw and cooked) and three fiber sources (control with no added fibre, 3% oat hulls and 3% soybean hulls). All diets included 1% celite (diatomaceous earth) as additional source of AIA. The techniques used for AIA determination were coded as VO and GA, respectively. The TTAR of dry matter and organic matter and the AMEn of the feeds differed (p ≤ 0.001) among diets and were lower when using GA than when using VO (p ≤ 0.05). However, no interaction between diet and methodology was observed. Moreover, the TTAR of nutrients as determined by both techniques, were highly correlated (r &gt; 0.98). We concluded that the GA methodology results in lower retention values than the VO methodology but that both methodologies can be used indistinctly to estimate TTAR of nutrients in broiler feeds.

[es] Los marcadores inertes se utilizan para estimar la retenci&oacute;n de nutrientes y energ&iacute;a metabolizable aparente corregida por nitr&oacute;geno (EMAn) en piensos. Las cenizas insolubles en &aacute;cido (CIA) son marcadores indigestibles utilizados en investigaci&oacute;n animal en sustituci&oacute;n de compuestos met&aacute;licos para evitar problemas medioambientales. En este ensayo, para determinar la retenci&oacute;n aparente de nutrientes y la EMAn en pollos, se compararon dos metodolog&iacute;as recomendadas para la determinaci&oacute;n del contenido de CIA en piensos y excretas. El dise&ntilde;o experimental fue completamente al azar con dos t&eacute;cnicas anal&iacute;ticas para la determinaci&oacute;n de CIA y 12 tratamientos experimentales que consist&iacute;an en la combinaci&oacute;n de dos cereales (ma&iacute;z y arroz), dos procesados t&eacute;rmicos del cereal (crudo y cocido) y tres fuentes de fibra (control sin fibra a&ntilde;adida, 3% cascarilla de avena, y 3% cascarilla de soja). Las t&eacute;cnicas usadas para la determinaci&oacute;n de CIA fueron codificadas como VO y GA, respectivamente. La retenci&oacute;n aparente de la materia seca, materia org&aacute;nica y EMAn de los piensos variaron (p &le; 0,001) con el tipo de pienso y fueron inferiores (p &le; 0,05) con la metodolog&iacute;a GA que con la metodolog&iacute;a VO. Sin embargo, no se observ&oacute; interacci&oacute;n entre tipo de pienso y t&eacute;cnica experimental. Adem&aacute;s, la retenci&oacute;n aparente de los nutrientes obtenida mediante ambas t&eacute;cnicas estuvo altamente correlacionada (r &gt; 0,98). Se concluye que la metodolog&iacute;a GA proporciona valores de retenci&oacute;n de nutrientes inferiores a los obtenidos con VO, aunque ambas pueden ser utilizadas indistintamente para estimar la digestibilidad fecal de nutrientes en avicultura.&nbsp;