Digestible energy and protein requirements for maintenance and growth of pacu ( Piaractus mesopotamicus ): A factorial approach-based model

Fredy Armando Aguilar Aguilar,José Eurico Possebon Cyrino,Gerson Barreto Mourão

doi:10.1590/1678-992x-2020-0026

Fredy Armando Aguilar Aguilar, José Eurico Possebon Cyrino + Show 1 more

Open Access

https://doi.org/10.1590/1678-992x-2020-0026

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Abstract

Results of nutrient requirements as determined in dose-response trials are valid only for fish within the same size range of that of experimental model fish. This study used the factorial approach to estimate digestible energy (DE) and digestible protein (DP) requirements for maintenance and growth of pacu ( Piaractus mesopotamicus ). Juvenile pacu (63.5 ± 1.27 g) were stocked in a recirculation system (26.89 ± 0.36 °C) for 58 days, and fed two daily meals. One diet contained 6.96 % lipids (LF) and another 9.98 % lipids (HF), both diets formulated to contain 32 % crude protein, theoretical dietary energy level for maintenance (52.23 kJ DE kg−0.80 d−1), in a completely randomized, 2 × 5 factorial experimental design. The apparent digestibility coefficients of energy and protein were 84.66 ± 0.27 % and 89.20 ± 0.61 %, respectively, determined in specific assays for the HF diet, while for the LF diet, the values were 84.52 ± 0.37 % and 89.19 ± 0.16 %, respectively. The analysis of growth and carcass composition data revealed that dietary requirements of digestible energy and protein for maintenance were not influenced by dietary lipid levels; however, requirements of growth digestible energy were higher for fish fed the LF diet (1.39) than for fish fed the HF diet (1.29). The requirement of DP for growth, expressed as g of DP per g of deposited protein, were higher for fish fed the LF diet than for fish fed the HF diet (1.70 vs 1.58).

Highlights

Nutritional requirements of pacu Piaractus mesopotamicus have already been assessed by doseresponse models, including energy, protein and amino acids requirements (e.g. Bicudo et al, 2009, 2010; Fernandes et al, 2001)
The feed conversion ratio, energy retention efficiency, and protein retention efficiency were affected by the feeding level
Ash, lipid, and energy contents of fish were affected by the feeding level: increasing feeding level increased the carcass dry matter (DM), lipid and energy contents; the ash contents decreased with increasing feeding levels (Table 3)

Summary

Introduction

Nutritional requirements of pacu Piaractus mesopotamicus have already been assessed by doseresponse models, including energy, protein and amino acids requirements (e.g. Bicudo et al, 2009, 2010; Fernandes et al, 2001). Nutrient requirements as determined in doseresponse trials are expressed as dietary nutrient or energy contents Such results are valid only for fish with body weights within the same range of that of fish used as the experimental model (Thornley and France, 2007). Theoretical estimations from biochemical production of ATP, either from glycolytic or lipid synthesis, and deposition routes help to explain the experimental findings (Blaxter, 1989). These limitations may be overcome by the use of the factorial approach to determine fish nutrient requirements, which has not been used to investigate the partitioning of DE and DP for pacu. The aim of the current study was to set basis for the use of the factorial approach to estimate the DE and DP requirements for maintenance and growth of the species, considering a possible effect of dietary lipid content

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