Lipid content and fatty acid profile of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles as affected by feed containing different amounts of plant protein sources

Long-term feeding of high plant-based diets supplemented with additive mixtures improves the fillet quality of rainbow trout, Oncorhynchus mykiss

Although more sustainable, feeding fish solely plant protein (PP) deteriorates their fillet quality more than animal counterparts, which additives can alleviate. This study investigated the effects of supplementing high PP diets with two additive mixtures on the fillet quality of rainbow trout (Oncorhynchus mykiss). Fish (∼2.2g) were fed with four isonitrogenous (42 % CP) and isolipidic (20 % lipid) diets: fishmeal-based (FM), plant-based (PP), PP + A1 (PP with a mixture of krill meal, taurine, and organic selenium) and PP + A2 (PP with a mixture of proline, hydroxyproline, and vitamin C) diets, for seven months. Different diets significantly (p < 0.05) affected fatty acid composition, textural profile, hydroxyproline and collagen content, and genes related to collagen synthesis. The short-term (ice vs. -20 °C) and long-term (-20 °C, 90 days) storage conditions showed significant (p < 0.05) effects on different fillet quality attributes, including protein secondary structures. Overall, supplementing additive mixtures improved the fresh and stored fillet quality.

Dietary Effects of a Short-Term Administration of Microalgae Blend on Growth Performance, Tissue Fatty Acids, and Predominant Intestinal Microbiota in Sparus aurata

Given the potential of microalgae as new aquafeed ingredients, this study focuses on using a blend of microalgae, Tisochrysis lutea, Nannochloropsis gaditana, and Scenedesmus almeriensis, as a dietary ingredient for feeding Sparus aurata juveniles. The growth performance, carcass composition, tissue fatty acid profile, and intestinal microbiota were evaluated after a 30 day-feeding period. A microalgae-free diet was used as control, and three experimental diets were formulated containing 5%, 15%, and 25% of the microalgae blend (MB-5%, MB-15%, and MB-25%, respectively). After 7, 15, and 30 days of feeding experimental diets, biological samples were taken. Growth performance and nutrient utilization were not significantly modified at the end of the experiment. Microalgae inclusion tended to decrease body lipids and affected the fatty acid profile, especially MB-25 diet increased DHA levels. Diet MB-25 promoted appropriate microbial diversity, favoring the presence of probiotic bacteria, such as Lactobacillus, and significantly influencing the fatty acid composition and lipid metabolism in fish. In conclusion, using a short pulse of dietary administration of 25% microalgal blend in S. aurata modulates the intestinal microbiota and lipid composition while maintaining growth performance.

Proximate Composition and Nutritional Profile of Rainbow Trout (Oncorhynchus mykiss) Heads and Skipjack tuna (Katsuwonus Pelamis) Heads

In order to evaluate the application potential of rainbow trout (Oncorhynchus mykiss) heads and skipjack tuna (Katsuwonus pelamis) heads; proximate composition, amino acids, fatty acids, carnosine, and anserine contents were analyzed in this study. Rainbow trout heads showed significantly higher protein (29.31 g/100 g FW, FW is abbreviation of fresh weight) and lipid (6.03 g/100 g FW) contents than skipjack tuna heads (18.47 g/100 g FW protein and 4.83 g/100 g FW lipid) (p < 0.05). Rainbow trout heads and skipjack tuna heads exhibited similar amino acid composition. Essential amino acids constituted more than 40% of total amino acids in both rainbow trout head and skipjack tuna head. The fatty acid profile was different between rainbow trout heads and skipjack tuna heads. Rainbow trout heads mainly contained 38.64% polyunsaturated fatty acids (PUFAs) and 38.57% monounsaturated fatty acids (MUFAs), whereas skipjack tuna heads mainly contained 54.46% saturated fatty acids (SFAs). Skipjack tuna heads contained 4563 mg/kg FW anserine and 1761 mg/kg FW carnosine, which were both significantly higher than those of rainbow trout heads (p < 0.05). These results demonstrate that both rainbow trout heads and skipjack tuna heads may be used as materials for recycling high-quality protein. Meanwhile, rainbow trout heads can be used to extract oil with high contents of unsaturated fatty acids, while skipjack tuna heads may be a source for obtaining carnosine and anserine.

Growth performance, body composition, and digestive functionality of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles fed diets including microalgae freeze-dried biomass

Senegalese sole is one of the most promising fish species cultivated in the Southern European countries. This study was aimed at assessing the effects of microalgae biomass added to diets for Senegalese sole juveniles on fish growing and condition status. Three isoproteic (52%) and isolipidic (10%) were formulated containing 15% Tisochrysis lutea (TISO), Nannochloropsis gaditana (NAN), or Scenedesmus almeriensis (SCE) biomass, respectively. An experimental microalgae-free diet (CT) and a commercial diet (COM) were used as controls. Fish were fed at 3% of their body weight for 85 days. Final body weight of fish fed microalgae-supplemented diets did not differ from group fed CT diet. Fish-fed CT, TISO, NAN, and SCE showed higher growth performance and nutrient utilization figures than specimen-fed COM diet. The highest carcass lipid content was found in COM group (141 g kg^-1), and no differences were observed in body protein content. Ash was significantly higher in TISO, NAN, and SCE groups compared to fish-fed CT. Muscle EPA and DHA contents were not modified owing to the different dietary treatments. The n3/n6 and EPA/DHA ratios in muscle were similar in all the experimental groups. The quantification of digestive proteolytic activities did not differ among experimental groups, although differences in the protease pattern in digestive extracts by zymography were revealed in those fish fed on COM diet. Both α-amylase activity in the intestinal lumen and leucine aminopeptidase in the intestinal tissue were significantly lower in COM fish. Specimens fed on SCE diet showed a higher leucine aminopeptidase activity associated to the intestinal tissue compared to NAN-fed fish (0.40 and 0.25 U g tissue^-1, respectively). The ultrastructural study revealed that the dietary inclusion of algal biomass, especially T. lutea and N. gaditana, had a positive impact on the absorptive capacity of the intestinal mucosa. The highest values for the parameters microvilli length and microvilli absorption surface were observed in fish fed on NAN diet (1.99 μm and 45.93 μm², respectively). Even though further studies aimed at optimizing commercial formulas for Senegalese sole are required prior to any large-scale practical utilization, the results obtained clearly suggest the potential of microalgae as dietary ingredients for this fish species.

Dietary Fatty Acid Metabolism is Affected More by Lipid Level than Source in Senegalese Sole Juveniles: Interactions for Optimal Dietary Formulation

This study analyses the effects of dietary lipid level and source on lipid absorption and metabolism in Senegalese sole (Solea senegalensis). Juvenile fish were fed 4 experimental diets containing either 100 % fish oil (FO) or 25 % FO and 75 % vegetable oil (VO; rapeseed, linseed and soybean oils) at two lipid levels (~8 or ~18 %). Effects were assessed on fish performance, body proximate composition and lipid accumulation, activity of hepatic lipogenic and fatty acid oxidative enzymes and, finally, on the expression of genes related to lipid metabolism in liver and intestine, and to intestinal absorption, both pre- and postprandially. Increased dietary lipid level had no major effects on growth and feeding performance (FCR), although fish fed FO had marginally better growth. Nevertheless, diets induced significant changes in lipid accumulation and metabolism. Hepatic lipid deposits were higher in fish fed VO, associated to increased hepatic ATP citrate lyase activity and up-regulated carnitine palmitoyltransferase 1 (cpt1) mRNA levels post-prandially. However, lipid level had a larger effect on gene expression of metabolic (lipogenesis and β-oxidation) genes than lipid source, mostly at fasting. High dietary lipid level down-regulated fatty acid synthase expression in liver and intestine, and increased cpt1 mRNA in liver. Large lipid accumulations were observed in the enterocytes of fish fed high lipid diets. This was possibly a result of a poor capacity to adapt to high dietary lipid level, as most genes involved in intestinal absorption were not regulated in response to the diet.

Targeting specific nutrient deficiencies in protein-restricted diets: some practical facts in PKU dietary management

Among aminoacidopathies, phenylketonuria (PKU) is the most prevalent one. Early diagnosis in the neonatal period with a prompt nutritional therapy (low natural-protein and phenylalanine diet, supplemented with phenylalanine-free amino acid mixtures and special low-protein foods) remains the mainstay of the treatment. Data considering nutrient contents of cooked dishes is lacking. In this study, fourteen dishes specifically prepared for PKU individuals were analysed, regarding the lipid profile and iron and zinc contents. These dishes are poor sources of essential nutrients like Fe, Zn or n-3 fatty acids, reinforcing the need for adequate supplementation to cover individual patients' needs. This study can contribute to a more accurate adjustment of PKU diets and supplementation in order to prevent eventual nutritional deficiencies. This study contributes to a better understanding of nutrient intake from PKU patients' meals, showing the need for dietary supplementation.