Improving nutrient availability of defatted rice bran using different phytase sources applied to grass carp (Ctenopharyngodon idella) diet.

Edi F Ries,Bruno B Loureiro,Gabriela A Macedo,Ana B.B Bender,Naglezi M Lovatto,Cristiano C Ferreira,Fernanda R Goulart,Leila P Da Silva

doi:10.1590/0001-3765202020190201

Abstract

In the present study, we evaluated the effects of the hydrolysis of phytate of defatted rice bran (DRB) by a pretreatment with non-commercial phytase produced by Saccharomyces cerevisiae (DRB-PS) compared to the application of Natuphos® (commercial phytase produced by the BASF Company) (DRB-PN) in diets for grass carp, Ctenopharyngodon idella. Fish (57.55 ± 0.4 g) fed one of the experimental diets in triplicates for 35 days. Effects of the phytase used on blood parameters, intestinal proteases and hepatic glucose were not observed (p > 0.05). Similarly, no differences were found for serum phosphorus (P). However, were found higher levels of calcium (9 and 5.25%) in the control treatment in relation to DRB-PS and DRB-PN respectively, besides higher calcium-phosphorus ratio was found in this treatment. For the fish carcass composition was not statistically different (p > 0.05) except total lipids, which showed its highest content in fish fed on the DRB-PN diet (p < 0.05). The obtained results suggested that the use of the phytase, irrespective to its source may eliminate the use of traditional P sources in fish diets.

Highlights

The grass carp (Ctenopharyngodon idellus) is as typical herbivorous fish and one of the most important freshwater species cultured in the world (FAO 2018)
In the fish fed on defatted rice bran (DRB)-PS and the DRB-PN diets, higher concentrations of liver protein were found
Higher levels for the calcium-phosphorus ration in the DRB-C-fed fish were observed compared to the ratio in those fed on the DRBPS diet (p < 0.05)

Summary

Introduction

The grass carp (Ctenopharyngodon idellus) is as typical herbivorous fish and one of the most important freshwater species cultured in the world (FAO 2018). The dietary products, which have plant origin, are being used in animal feeds including fish. Plant ingredients contain antinutritional factors, such as phytic acid or phytase, which form complexes with minerals, proteins, lipids, and starches (Francis et al 2001, Graf & Faton 1990). These complexes are not absorbed in the gastrointestinal tract of fish, lowering their digestion and bioavailability (Gilani et al 2005, Greiner & Konietzny 2006, Kumar et al 2011, Sugiura et al 2001). The excess of phosphorus added to the feed, phytate-related phosphorus and other unused minerals are

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Discussion

Conclusion