We concluded that bean meal obtained from fermentation or dehulling represents a low-cost alternative for diets for tilapia. © 2017 Society of Chemical Industry.

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Among the most typical feed sources for tilapia, plants represent a low-cost source in substituting for traditional high-cost feed ingredients. Fermentation, hardening and dehulling are common grains processing techniques to make plant nutrients available and more digestible to fish. Apparent digestibility coefficients (ADC) of dry matter and protein, and antinutrients (phytic acid and tannins) in fermented, hardened and dehulled chickpea (Cicer arietinum) meals were determined for juvenile Nile tilapia (Oreochromis niloticus). The highest ADC was obtained with processed (fermented, hardened and dehulled) chickpea meals compared with non-processed. Results indicated that fermentation increased the protein content by 13.1%, decreased the content of ash and phytic acid (47.5 and 45%, respectively), and increased the ingredient apparent digestibility of dry matter (ADM) by 23.2%, and the ingredient apparent digestibility of protein (ADP) by 41.9%. Dehulling meal increased the protein (5.7%) and lipid (6.4%) content of chickpea grains; decreased fiber, ash and tannin content (75.3%, 19.1%, and 84.5%, respectively); and increased ADM by 12.8%, and ADP by 10.4%. We conclude that fermented, hardened and dehulled chickpea meals represent a potential alternative in diets for juvenile O. niloticus.Additional key words: aquafeeds; plant-based feed ingredients; bioprocessing; antinutritional compounds; tilapia. Abbreviations used: ADC (apparent digestibility coefficients); ADM (apparent digestibility of dry matter); ADP (apparent digestibility of protein); SSF (solid-state fermentation).Authors' contributions: Conceived and designed the experiments: RGD and HRG. Performed the experiments: FJVG, RGD and BLCR. Analyzed the data: FJVG, MGU and HRG. All authors wrote and approved the final manuscript.Citation: Valdez-González, F. J.; Gutiérrez-Dorado, R.; García-Ulloa, M.; Cuevas-Rodríguez, B. L.; Rodríguez-González, H. (2018). Effect of fermented, hardened, and dehulled of chickpea (Cicer arietinum) meals in digestibility and antinutrients in diets for tilapia (Oreochromis niloticus).

In order to improve the cost-benefit relationship in aquaculture production systems, several technological advances have been formulated. The biofloc technology system (BFT) offers the advantage of functioning as a water treatment method, allowing the conversion of ammonium to nitrites and nitrates by using the properties of chemo-autotrophic bacteria. Biofloc technology system is considered a relevant cost-effective and ecological method, with potential use in aquaculture (Crab, Defoirdt, Bossier, & Verstraete, 2012). In addition, BFT promotes biosecurity by preventing the proliferation of pathogenic organisms, as well as the generation of bacterial protein flocs that are constantly renewed in the system, favouring the continuous in situ production of a microbial protein source (Avnimelech, 2012). The biofloc is constituted by a suspended heterogeneous mixture of microorganisms containing fungi, algae, microalgae, bacteria (autotrophic, chemo-autotrophic, photo-autotrophic, filamentous, heterotrophic), and flagellates and ciliates among other protozoa. The biofloc system also comprises organic matter in the form of colloids, organic polymers, alkaline earth metals, undigested food, organic waste, dead