Evidence of enteritis, hepatic steatosis and jaundice in juvenile pirarucu (Arapaima gigas) fed high levels of soybean meal

ABSTRACTThis study evaluated the effects of replacing dietary fishmeal with increasing levels of soybean meal (0, 15, 30, 45 and 60% corresponding to 0, 11, 22, 33 and 44% inclusion in the formulated diet) on the intestine and liver histomorphology of juvenile pirarucu Arapaima gigas (233 ± 12 g; mean ± SD) fed for 120 days. At the end of the feeding trial, fish fed diets with higher soybean levels (45 and 60%) presented clinical signs such as appetite loss, cachexia and jaundice. In addition, fish fed on 45% and 60% soybean meal had histomorphological alterations in the middle and posterior portions of the intestinal mucosa (enteritis) and high liver lipid deposition (steatosis). Therefore, 45% or 60% of soybean meal is not recommended; however, a replacement of fishmeal by soybean meal of up to 30% (22% inclusion) can be used in diets to feed juvenile pirarucu for long periods.KEYWORDS: Amazon fishliver and intestinal histomorphologyfishmeal replacementplant-based ingredientssoybean meal AcknowledgmentsAuthors are grateful to the Laboratories of Physiology Applied to Pisciculture (LAFAP) and Thematic Laboratory of Optical and Electronic Microscopy (LTMOE) at the National Institute of Amazonian Research (INPA), to Laboratories of Animal Physiology and Functional Histology at the Federal University of Amazonas (UFAM). We also appreciate the technical support of Laboratories of Immunology and Nutrition from the Department of Biology, and Center of Interdisciplinary Marine and Environmental Research at the University of Porto, Portugal.Disclosure statementNo potential conflict of interest was reported by the author(s).Author contributionsConceptualization: Renata Maria da Silva, Helena Peres and Jaydione Luiz Marcon; validation, Renata Maria da Silva and Helena Peres; Formal analysis: Renata Maria da Silva, Helena Peres, and Sergio Fernández-Boo; Investigation: Renata Maria da Silva, Helena Peres, Sergio Fernández-Boo and José Fernando Marques Barcellos; Resources: Helena Peres and Jaydione Luiz Marcon; Writing-original draft preparation: Renata Maria da Silva; Writing-review and editing: Helena Peres, Sergio Fernández-Boo, José Fernando Marques Barcellos and Jaydione Luiz Marcon; Supervision: Helena Peres and Jaydione Luiz Marcon; Project administration: Helena Peres and Jaydione Luiz Marcon; Funding acquisition: Helena Peres. All authors have read and agreed to the published version of the manuscript.Data availability statementThe data that support the findings of this study are available from the corresponding author upon reasonable request.Institutional Review Board StatementThis study was previously approved by the Animal Ethics Committee at INPA (protocol #004/2016-CEUA/INPA).Additional informationFundingThe projects DARPA/FINEP (Brazil) (process 01.09.0472.00–FINEP) and ADAPTA/INPA (INCT/CNPq/FAPEAM, Brazil) (CNPq: 573976/2008-2; FAPEAM: 3159/08) gave part of financial support. Additional funding support came from R and D and IINNOVMAR - Innovation and Sustainability in the Management and Exploitation of Marine Resources (NORTE-01-0145-FEDER000035) within the line of research INSEAFOOD - (NORTE2020) through the European Regional Development Fund (ERDF) and the Operational Competitiveness Program (COMPETE), through the European Regional Development Fund (ERDF) and funds obtained through the Foundation for Science and Technology (FCT), under the Pest-C/MAR/LA0015/2013 project. RMS was funded by a doctoral scholarship program for Private Education Institutions (PROSUP/CAPES, Brazil; process 12006017003P5) and the Sandwich Doctorate Program Abroad (PDSE/CAPES, Brazil, process 88881.134762/2016-01).