Seriola spp. represents a promising group of species for aquaculture expansion worldwide due to their high growth rates , adaptability to different culture systems, and attractive economic value. In Mexico, to be sustainable the growing industry of California yellowtail Seriola dorsalis will need the use of diets low or fishmeal (FM) and fish oil (FO) free diets . The evaluation of new complementary ingredients is essential to reduce the dependency on the latter marine resources. In recent years, the advance and expansion of single-cell biomass technology has become an innovative option to produce high-quality proteins and oils rich in LC-PUFAs from microalgae, fungi, and bacteria. Therefore, this study aimed to evaluate the effect on growth performance and gut health of replacing FM and FO with Arthrospira platensis meal and Schizochytrium limacinum meals in California yellowtail juvenile diets.
Four isoproteic (50% CP) and isolipidic (17% CL) experimental diets were formulated to replace fishmeal and fish oil at 0%, 20%, 40% and 80% with a blend of autotroph freshwater microalga A. platensis meal and the heterotroph marine S. limacinum meal. Fifteen fish (13.1 ± 0.9 g) were stock in fiberglass tanks and fed each diet for 35 days to apparent satiation (three times a day). Each experimental diet was evaluated in triplicate. At the end of the bioassay, growth performance, feed utilization, somatic indexes, and whole-body composition were assessed. Three fish were used to evaluate intestinal integrity according to Fuentes-Quesada et al., (2018) and marine resources dependency ratios were determined using the equation described by Sarker et al., (2013). Data were analyzed by one-way ANOVA (P < 0.05), followed by a post-hoc Tukey rank test.
Fish fed with ALG-20 and ALG-40 diets presented a significantly higher performance in growth variables compared to those fed with AGL-0 and ALG-80. Feed intake of fish fed diets containing microalgae meals was higher compared with the control diet (ALG-0). Although, the inclusion of microalgae meals increased FCR and decreased nutrient retention, no significant differences were found between fish fed diets ALG-20 and the control diet. As the inclusion levels of microalgae meals increased in the diet, fish content of CP and CL were gradually reduced, and the opposite effect was found for moisture, ash, and NFE. In terms of whole-body fatty acid profile, the inclusion of microalgae increased the content of DHA and saturated fatty acids, but decrease the content of EPA and monounsaturated fatty acids. Microalgae inclusion in diets significantly reduced the microvilli height in the distal intestine compared to fish fed the ALG-0 diet. Meanwhile, fish fed diet ALG-20 and ALG-40 showed a higher number of mucosal folds compared with those fish fed ALG-0 and ALG-80. Fish fed with ALG-20 reduced in 10% and 13% the dependency of FM and FO in California yellowtail diets, respectively.
Fuentes-Quesada, J.P., et al., 2018. Aquaculture, 495: 78-89
Sarker , P.K., et al., 2013. Reviews in Aquaculture 5, 199-219