Determination of apparent digestibility coefficient in fish by stable carbon isotopes

Abstract

Estimation of the apparent digestibility coefficient ADC(%) of C3 and C4 plants in experimental diets for fingerlings of tambaqui (Colossoma macropomum, Cuvier, 1818) was calculated by applying chromic oxide (Cr2O3) external marker methodology and by a proposed mathematical expression based on the isotopic composition (δ13C). A total of 240 tambaqui fingerlings each weighing ±48.2 g and measuring ±9.8 cm were maintained in eight 500‐L aquariums specially designed for faeces collection. The ADC(%) of the C3 and C4 diets did not differ significantly between the two methods, producing results of 75.6%; 76.2% and 74.4%; 72.8%, respectively. The ADC(%) results obtained by isotopic method presented less variation than by chromic oxide. The proposed mathematical expression for calculating the ADC(%) based on δ13C values offers an alternative methodology, which can reduce errors and diminish the effort required to collect biological material. However, it is important to note that this method is limited to analysis of diets or food items with distinct isotopic signals.

Nutrients apparent digestibility coefficients of selected protein sources for juvenile Siberian sturgeon (Acipenser baeriiBrandt), compared by two chromic oxide analyses methods

“…Determination method of Cr 2 O 3 is important for the accurate results of the ADCs of feedstuffs. Oliveira et al. (2007) observed considerable variation in ADC values by AC method.…”

“…This might suggest that the ADC of high protein content feedstuffs determined by AC method was more inaccurate. In AC method, the procession of acid digestion is difficult to be controlled stably, the inaccurate results of ADCs may be from the possibility of progressive amounts of tracer being leached from the samples during repetitions, and also from analytical error in the laboratory (Oliveira et al. 2007), which led to the lower recovery rate and higher CV of Cr 2 O 3 determined by AC method in this study.…”

“…1999; Austreng et al. 2000;Vandenberg & De La Noue 2001; Oliveira et al. 2007), the sampling periods (Allan et al.…”

“…Both inductively coupled plasma atomic emission spectrometry (ICP‐AES) and acid‐digestion colorimetry (AC) are typical analysis instruments for Cr 2 O 3 determination. However, a larger variation was found in apparent digestibility coefficient (ADC) values utilizing the AC method because of the possibility of progressive amounts of tracer being leached from the samples during repetitions, and also from analytical error in the laboratory (Oliveira et al. 2007).…”

Natural Stable Isotopes for Determination of Gastrointestinal Transit Time in Fish

“…This study proposed the stable isotope technique to be an alternative and more accurate method to determine GTT when compared to the inert marker method. Stable isotopes have been successfully used to investigate natural ingredients in animal diets (Gamboa‐Delgado and Le Vay ), food digestibility (Oliveira et al ), the metabolism in different tissues (by indicating the turnover rates of carbon and nitrogen isotopes) (Jomori et al ), and the traceability of ingredients that are controlled or prohibited in animal diets (Carrijo et al ). This technique is adequate when the provided diets have different isotopic signatures because the isotopic composition and body fluids of animal tissues are influenced by the diet (Caldara et al ).…”