Testing various faeces-collecting methods to improve digestibility studies with tambaqui, Colossoma macropomum (Cuvier, 1816)

Abstract

Summary Determining the ingredients and/or digestibility of a diet is one of the most important steps in fish nutrition for accurate diet formulation. Additionally, the use of digestible nutrient data in fish feed formulation can reduce the environmental impact of aquaculture. To properly determine the nutrient digestibility (ADC) of a feed ingredient and/or compound diets, an accurate faeces‐collecting method should be used to provide reliable information on the digestion capacity of a determined species. Thus, a series of two trials were performed aiming to evaluate and standardize a faeces‐collecting method for Colossoma macropomum. Faeces from all groups were collected using one of the methods. In trial 1, two faeces‐collecting methods (sedimentation and dissection) were evaluated using 80 juveniles (170 g average weight) randomly assigned into four 310‐L aquaria. In trial 2, 135 juveniles (300 g average weight) were randomly distributed into nine 310‐L aquaria and fed a control diet (without binder) and diets containing a dietary binder at 0, 2 and 4 g kg−1 diet aiming to test the effect of binder inclusion on the ADC of nutrients. Fish were fed in triplicate groups per diet. Results showed that the dissection method provided the lowest ADC values for dry matter, phosphorus and gross energy. ADC of dry matter tended to decrease up to 5 h (305 min) of faeces immersion and seem to stabilize afterwards. Using 4 g kg−1 of dietary binder tended to reduce the leaching of DM, and no effect was observed on the protein digestibility. Phosphorus was the nutrient most prone to leaching in faeces. Faeces collection within 1 h is recommended in the sedimentation method in C. macropomum digestibility studies; the use of dietary binder at 4 g kg−1 may be a useful approach to reduce nutrient leaching in the faeces.

Effect of replacing fish meal protein by crystalline amino acid and soy protein concentrate on growth, feed utilization, and metabolism of tambaqui Colossoma macropomum juveniles

“…Both systems were connected to their biological filter, and water was recirculated at 2.5 L/min with constant aeration throughout the trial. This procedure was previously described and reduces the nutrient leaching in tambaqui feces collected using the sedimentation method (Mota, Araújo, Pádua, Martins, & Guimarães, 2015).…”

Dietary available phosphorus requirement for tambaqui,Colossoma macropomum, juveniles based on growth, haematology and bone mineralization

“…() with slight modifications proposed by Mota et al . () for collecting faeces with tambaqui. Briefly, all fish were fed the control diet for 15 days; then, experimental diets were randomly assigned to the feeding aquaria; fish were fed during 7 days prior to the beginning of faecal collection (acclimatization period); the first faeces collection was carried out.…”

Optimizing methodological aspects of stool collection by sedimentation in digestibility studies with pirarucu ( Arapaima gigas )

“…Passive stool collection by sedimentation in cylindrical‐conical tanks (adapted Guelph method) is often used in in vivo digestibility studies with fish (Abimorad & Carneiro, 2004; Kitagima & Fracalossi, 2010; Hien et al, 2010; Mota et al, 2015; Rodrigues et al, 2012; Gominho‐Rosa et al, 2015). In this type of structure, the stool sediments quickly, without depositing in corners, thereby decreasing leaching losses.…”