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- Metabolic and nutritional responses of Nile tilapia juveniles to dietary methionine sourcesPublication . Teodósio, Rita; Engrola, Sofia; Cabano, Miguel; Colen, R.; Masagounder, Karthik; Raquel Cêa de Aragão Teixeira, CláudiaCommercial diets for tilapia juveniles contain high levels of plant protein sources. Soybean meal has been utilised due to its high protein content; however, soy-based diets are limited in methionine (Met) and require its supplementation to fulfil fish requirements. DL-Methinone (DL-Met) and Ca bis-methionine hydroxyl analogue (MHA-Ca) are synthetic Met sources supplemented in aquafeeds, which may differ in biological efficiency due to structural differences. The present study evaluated the effect of both methionine sources on metabolism and growth of Nile tilapia. A growth trial was performed using three isonitrogenous and isoenergetic diets, containing plant ingredients as protein sources: DLM and MHA diets were supplemented on equimolar levels of Met, while REF diet was not supplemented. Hepatic free Met and one-carbon metabolites were determined in fish fed for 57 d. Metabolism of DL-Met and MHA was analysed by an in vivo time-course trial using 14C-labelled tracers. Only DLMet supplementation significantly increased final body weight and improved feed conversion and protein efficiency ratios compared with the REF diet. Our findings indicate that Met in DLM fed fish follows the transsulphuration pathway, while in fish fed MHA and REF diets it is reme thylated. The in vivo trial revealed that 14C-DL-Met is absorbed faster and more retained than 14C-MHA, resulting in a greater availability of free Met in the tissues when fish is fed with DLM diet. Our study indicates that dietary DL-Met supplementation improves growth performance and N retention, and that Met absorption and utilisation are influenced by the dietary source in tilapia juveniles.
- Impact of fish meal replacement by alternative and sustainable ingredients in diets for gilthead seabream (Sparus aurata Linnaeus, 1758) juvenilesPublication . Cabano, Miguel Orelhas; Aragão, CláudiaAquaculture is the animal production sector that is growing at a faster rate in the world but in the last decades, as fish meal has been widely used as the main dietary protein source, the industry became highly dependent on this ingredient. Fish meal prices are predicted to increase in the next 15 years, and aquaculture cannot be dependent on this protein source if the same growth registered in the past is maintained. Based on this fact, alternatives to fish meal that offer the same or even better results must be found. In the past years, research towards finding new protein sources have increased and plant-based proteins and terrestrial animal proteins have shown a great potential to replace the widely used fish meal in fish diets. Therefore, the aim of this Thesis was to evaluate growth performance, body composition and nutrient balance in gilthead seabream juveniles fed diets with high levels of fish meal replacement by alternative and sustainable ingredients. Three experimental diets were formulated including processed animal proteins (PAP), plant proteins (PLANT) or a mixture of micro/macro algae, insects and yeast (EMERG) as main protein sources. The performance of fish fed with these three diets was compared with a control (CTRL) diet, formulated to be similar to a commercial feed used nowadays in gilthead seabream culture. At the end of the experiment, fish fed with the PAP and PLANT diets showed improved growth performance, more efficient dietary nutrient utilization and lower environmental impact compared with fish fed with the CTRL diet. Performance of fish fed with the EMERG diet was, in general, negatively affected. The results obtained in the present study show that the gilthead seabream culture can be improved and can even be more environmentally sustainable using PAP and PLANT diets that contained only 5% of marine-derived ingredients.
- Sustainable feed formulation to community‐based aquaculture: Oreochromis niloticus fingerlings performance and antioxidant statusPublication . Pires, Sílvia F. S.; Vital, Inês; Pereira, Vitória; Bustani, Henriques; Aragão, Cláudia; Engrola, Sofia; Cabano, Miguel; Dias, Jorge; Soares, Amadeu M. V. M.; Rodrigues, Andreia C. M.; Rocha, Rui J. M.Community-based aquaculture can reduce dependence on natural resources, promote biodiversity conservation, and improve local economies and food security. However, this activity is highly dependent on local conditions regarding natural resources, such as the availability of produced organisms, adequate feeds, and environmental factors. As ectothermic organisms, fish are more susceptible to temperature fluctuations in culture conditions. A set of raw ingredients (e.g., cassava and local beans) produced or available in villages from Cabo Delgado (Mozambique) with nutritional potential for fish feed were selected to produce an experimental diet. The following objectives were defined: (1) evaluate growth performance of tilapia fingerlings fed a diet produced with local ingredients, compared with a commercial-like diet; and (2) evaluate the response to thermal stress (18, 26, and 32degree celsius) by tilapia fingerlings fed with tested diets. Tilapia fed with an experimental diet presented lower growth rates, lower DNA damage, higher neurophysiological, and antioxidant activity, leading to increased oxidative stress. Regarding energy budget, tilapia fed with the experimental diet presented higher protein content at 26degree celsius and lipids at 18degree celsius, leading to greater energy available at these temperatures. Overall, local ingredients can be successfully used as an additional feed source for tilapia production in community-based aquaculture in earthen ponds.
- Modulation of dietary protein to lipid ratios for gilthead seabream on-growing during summer temperature conditionsPublication . Aragão, Cláudia; Cabano, Miguel; Colen, R.; Teodósio, Rita; Gisbert, Enric; Dias, Jorge; Engrola, SofiaGilthead seabream (Sparus aurata) tend to increase fat deposition during summer farming conditions in the Mediterranean, which may negatively affect productive performance and consumers' quality perception of the final product. Therefore, this study evaluated the impacts of protein to lipid ratios in low fishmeal/fish oil diets on growth performance, body composition, feed conversion and nutrient utilization of seabream on-grown during summer temperature conditions. The experimental diets contained low levels of fishmeal, fish oil, and crude protein (39%), differing in crude lipid content: 16% (MF diet) or 12% (LF diet). A growth trial was per-formed with seabream (initial weight: 100 & PLUSMN; 7 g) from August to October (water temperature: 23.1 & PLUSMN; 2.2 & DEG;C). A digestibility trial was also performed (at 23 & DEG;C). Key performance indicators, whole-body composition and ac-tivities of digestive enzymes were evaluated at the end of the experiment (64 days). Low dietary lipid levels negatively affected lipid, energy, and amino acid digestibility, and as a result, fish fed the LF diet presented higher nitrogen faecal losses. Still, the decrease in nutrient digestibility was not related to dietary effects on the digestive enzyme activities. The experimental diets did not compromise the activity of pancreatic, gastric, and intestinal digestive enzymes nor feed utilization, but a slight growth impairment was observed in fish fed the LF diet, probably due to the lower amino acid and lipid digestibility. However, a potential benefit of this dietary treatment towards reducing fat accumulation in seabream during summer was observed. Nevertheless, the environmental impact of the nitrogen losses during seabream on-growing should be considered when estimating the sustainability of the production. This study demonstrated that the optimisation of diet formulations should account for the environmental conditions, especially in Mediterranean aquaculture, so the economic and envi-ronmental impacts may be correctly evaluated towards a more sustainable fish production.
- Alternative formulations for gilthead seabream diets: towards a more sustainable productionPublication . Aragão, Cláudia; Cabano, Miguel; Colen, R.; Fuentes, Juan; Dias, JorgeTo support the expected increase in aquaculture production during the next years, a wider range of alternative ingredients to fishmeal is needed, towards contributing to an increase in production sustainability. This study aimed to test diets formulated with non‐conventional feed ingredients on gilthead seabream (Sparus aurata) growth performance, feed utilization, apparent digestibility of nutrients and nutrient outputs to the environment. Four isonitrogenous and isoenergetic diets were formulated: a control diet (CTRL) similar to a commercial feed and three experimental diets containing, as main protein sources, plant by‐products, glutens and concentrates (PLANT); processed animal proteins (PAP); or micro/macroalgae, insect meals and yeast (EMERG). Diets were tested in triplicate during 80 days. The EMERG treatment resulted in lower fish growth performance, higher FCR and lower nutrient and energy retentions than the other treatments. The lowest protein digestibility was found for the EMERG diet, which caused increased nitrogen losses. The PLANT and PAP treatments resulted in better fish growth performance, higher nutrient and energy retentions, and lower FCR than the CTRL treatment. The significant improvement in FCR found for fish fed PLANT and PAP diets and the high protein digestibility of these diets contribute towards minimizing the environmental impacts of seabream production.
- Fish protein hydrolysates mitigate the adverse effects of no‐fishmeal diets in gilthead seabream juvenilesPublication . Aragão, Cláudia; Pontes Barbosa Colen, Rita Isabel; Teodósio, Rita; Orelhas Cabano, Miguel; Antelo, Luís T.; Vázquez, José Antonio; Engrola, Sofia; Mansour Torfi MozanzadehThe aquaculture industry must continue to reduce its reliance on finite marine ingredients and promote biocircularity to enhance sustainability. This study evaluated the effects of no-fishmeal (FM) diets and fish protein hydrolysates (FPHs) on the growth performance, antioxidant status, and immune responses of gilthead seabream (Sparus aurata). Following established conditions, two FPHs were prepared from the enzymatic hydrolysis of discards from whole-body blue whiting (Micromesistius poutassou) and gurnard heads (Trigla spp.); the former contained a higher proportion of large peptides (LPs), while the latter had more small peptides (SPs). Four isoproteic (48%) and isolipic (16%) diets were tested: a commercial (COM)-like diet with 35% FM, 10% poultry meal, and 5% soy protein concentrate; a FUTURE (FUT) diet, without FM or soy protein concentrate, containing 25% poultry meal; and two FUT diets supplemented with FPH (FUTLP and FUTSP). Gilthead seabream (initial weight +/- 8.0 g) was distributed into 500 L tanks at an initial density of 1.4 kg m-3 and fed the experimental diets to apparent satiety for 8 weeks. Sampling was performed at the end of the growth trial, followed by a digestibility trial. Nutrient and energy digestibilities were significantly lower in the FUT than in the COM diet, with protein and energy digestibilities being 7% and 16% lower, respectively, in the FUT treatment, leading to higher nitrogen losses. Growth performance and feed utilization were negatively impacted in the FUT treatment, with weight gain of only 310 +/- 33% compared to 482 +/- 22% in the COM treatment. Additionally, immune responses in plasma and antioxidant status in the liver were slightly impaired in the FUT treatment. Supplementation of FPH to the FUT diet mitigated or even reversed these negative effects. The results confirmed that including small- and medium-sized peptides in no-FM diets is more beneficial than using larger ones.