Evaluation of IMTA-produced seaweeds (Gracilaria, Porphyra, and Ulva) as dietary ingredients in Nile tilapia, Oreochromis niloticus L., juveniles. Effects on growth performance and gut histology

Abstract

The present study evaluated the effects of the inclusion of three seaweeds, Gracilaria vermiculophylla (GRA), Porphyra dioica (POR), and Ulva spp. (ULV), as dietary ingredients for Nile tilapia (Oreochromis niloticus) juveniles, on the growth performance, body composition, and gut histology. Three experimental diets (GRA, POR, and ULV) were formulated to replace 10 % of whole diet by each of the three seaweeds. A control diet (CTRL) was used, without inclusion of any seaweed. Diets were fed to triplicate groups of 25 Nile tilapia juveniles, with an average body weight (ABW) of 12.1 g, in an 84-day trial. At the end of the trial, growth performance was significantly reduced (P<0.05) in fish fed the GRA diet, whereas the feed conversion ratio increased significantly in those fish. None of the treatments caused adverse effects on body composition. The inclusion of the three seaweeds in the diet led to evident changes in the fish digestive system morphology with significant reduction of villi length on GRA diet. The results obtained in this study suggest the usefulness of P. dioica and Ulva spp. to partially replace fishmeal in practical diets for tilapia juveniles up to 10 %, as no negative consequences on growth performance or body composition were observed. However, the inclusion of 10 % G. vermiculophylla seems to have a negative effect in diet palatability, reducing fish feed intake and growth performance.

Optimizing diets to decrease environmental impact of Nile tilapia (Oreochromis niloticus) production

“…All experimental diets were suitable for the fish; that is, the levels of inclusion of protein in diets of Nile tilapia juveniles had no detrimental effect on survival, weight gain, daily growth index and daily voluntary feed intake. The fish growth performance was similar to other studies (Abdel‐Tawwab et al, ; El‐Saidy & Gaber, ; Hernández et al, ; Silva et al, ), particularly taking into account that the experimental diets contained no fish meal nor fish oil in their formulation.…”

“…Feed conversion ratio for Nile tilapia found in the literature varies significantly, which is likely due to discrepancies in experimental diets and conditions, such as feed quality (physical and nutritional), feeding regime, fish age and size. Considering fish size and dietary protein sources (mainly plant ingredients), the FCR values in the present study are lower or within the values found in similar studies (Abdel‐Tawwab et al, ; El‐Saidy & Gaber, ; Hernández et al, ; Silva et al, ). Based on the overall growth performance and the FCR observed in the present study, it is implied that the dietary protein levels can be reduced down to 300 g/kg diet without hindering fish growth performance and FCR.…”

Antioxidant-related parameters, digestive enzyme activity and intestinal morphology in rainbow trout (Oncorhynchus mykiss) fry fed graded levels of red seaweed,Gracilaria pygmaea

“…The shorter villi in GL-90 and GL-120 groups might be attributed to the presence of several ANFs in Gracilaria species, as proposed by Silva et al (2015). It has been demonstrated that Gracilaria species contain several ANFs (Benevides et al, 1998) which are resistant to proteolytic hydrolysis by digestive enzymes and harmful to the gut (Bardocz, Ewen, Grant, & Pusztai, 1995).…”

Macroalgae as a sustainable aquafeed ingredient

“…Morphological examinations carried out on Nile tilapia ( O. niloticus ) showed there was a reduction in both proximal intestinal diameter and villi length (Silva et al . ). This was particularly evident after being fed for 84 days on 10% inclusion diet.…”