Estudio comparativo de dos metodologías analíticas utilizadas para la determinación de cenizas insolubles en ácido para evaluar la retención de nutrientes en pollos de engorde

[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 > 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 retención de nutrientes y energía metabolizable aparente corregida por nitrógeno (EMAn) en piensos. Las cenizas insolubles en ácido (CIA) son marcadores indigestibles utilizados en investigación animal en sustitución de compuestos metálicos para evitar problemas medioambientales. En este ensayo, para determinar la retención aparente de nutrientes y la EMAn en pollos, se compararon dos metodologías recomendadas para la determinación del contenido de CIA en piensos y excretas. El diseño experimental fue completamente al azar con dos técnicas analíticas para la determinación de CIA y 12 tratamientos experimentales que consistían en la combinación de dos cereales (maíz y arroz), dos procesados térmicos del cereal (crudo y cocido) y tres fuentes de fibra (control sin fibra añadida, 3% cascarilla de avena, y 3% cascarilla de soja). Las técnicas usadas para la determinación de CIA fueron codificadas como VO y GA, respectivamente. La retención aparente de la materia seca, materia orgánica y EMAn de los piensos variaron (p ≤ 0,001) con el tipo de pienso y fueron inferiores (p ≤ 0,05) con la metodología GA que con la metodología VO. Sin embargo, no se observó interacción entre tipo de pienso y técnica experimental. Además, la retención aparente de los nutrientes obtenida mediante ambas técnicas estuvo altamente correlacionada (r > 0,98). Se concluye que la metodología GA proporciona valores de retención de nutrientes inferiores a los obtenidos con VO, aunque ambas pueden ser utilizadas indistintamente para estimar la digestibilidad fecal de nutrientes en avicultura.This work was supported by project AGL2008-03506 (Ministerio de Ciencia e Innovación, Madrid).Peer Reviewe

Comparative study of two analytical procedures for the determination of acid insoluble ash for evaluation of nutrient retention in broilers

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 > 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 feed