Genetic selection for high growth improves the efficiency of gilthead sea bream (Sparus aurata) in using novel diets with insect meal, single-cell protein and a DHA rich-microalgal oil

Genetic selection and novel raw materials for aquafeeds are current key tools in the ongoing effort to increase the productivity, efficiency, and sustainability of the aquaculture sector. Selective breeding could also improve the utilization of novel dietary formulations with emergent ingredients. Gilthead sea bream juveniles, either coming from a selective breeding program based on growth traits, or a non-selected population, were nutritionally challenged with two novel dietary formulations that were compared with a Control diet based on 15% FM and 6% FO dietary commercial levels for this species. The novel formulations included an insect meal diet (INS) at 5% of the diet to replace 33.3% of the dietary FM, or a single-cell protein diet (SCP) at 10% of the diet and to replace 66.7% of the dietary FM. Fish oil was also totally replaced in these diets by a blend of poultry oil and Veramaris algal oil. Better growth and feed utilization of the selected genotype compared to non-selected fish was observed, at any of the diets assayed. INS and SCP novel diets reduced general performance of fish by reducing feed intake. However, selected fish fed novel diets showed very similar growth and lower feed conversion ratio compared with non-selected fish fed a control diet. The novel formulations increased n-3 LC-PUFA in fish tissues, particularly DHA, irrespective of the genotype, as a result of the dietary inclusion of the DHA-rich microalgal oil. Neither genetic selection nor the use of novel raw materials affected fillet proximate composition and consequently, sea bream fillet quality in terms of texture and sensorial perception of consumers. Overall, the results reaffirm the positive effects of selective breeding programs in improving sea bream key productive indicators, as well as support the use of novel dietary formulations, using insect meal from H. illucens, single-cell protein from M. capsulatus as partial replacers of FM in diets for gilthead sea bream (33 and 66% of replacement, respectively), and a blend of DHA-rich microalgal and poultry oils as total replacer of FO.This work was supported by the European Union‘s Horizon 2020 research and innovation program under grant agreement no. 818367; AquaIMPACT—Genomic and nutritional innovations for genetically superior farmed fish to improve efficiency in European aquaculture.info:eu-repo/semantics/publishedVersio

Integrated study on production performance and quality traits of European sea bass ( Dicentrarchus labrax ) fed high plant protein diets

In the issue of fishmeal replacement, besides maintaining optimal growth, a key area of investigation for continuing to improve modern aquafeeds includes the evaluation of the effects of plant ingredients on fish quality. It is generally accepted that farmed fish quality can be influenced by the formulation of composition of their feed. Hence, the aim of the present research was to evaluate plant protein inclusion up to 84% of the overall protein content in an integrated study on growth and quality traits of European sea bass. Three diets were formulated to contain increasing plant protein levels (50, 67 and 84%; 50PP, 67PP and 84PP, respectively), with fishmeal dietary levels at 30, 20 and 10%, respectively. No significant differences due to reducing fishmeal content were observed after 118 days in terms of growth (final body weight and specific growth rate) and feed intake, even though a trend towards lower growth performance at higher fishmeal replacement levels was observed. Fish fed diet 50PP showed lower feed conversion rate in comparison to those fed diet 84PP, while no differences were recorded between diet 50PP and 67PP. No significant differences among treatments were found in protein efficiency rate. On the contrary, fish fed diet 84PP showed lower gross protein efficiency in comparison to those fed diet 50PP and 67PP. No significant differences in biometric indices and fillet composition were observed. No significant differences were found in pH, liquid holding capacity and skin colour measurements between treatments, while regarding fillet colour, significant differences were found only for H\ub0ab. In conclusion, our findings demonstrated that dietary plant proteins up to 84% of the overall protein content had no effects on quality traits of European sea bass in comparison with 50% and 67%. All experimental groups showed similar growth even though 84% plant protein inclusion negatively influenced feed and protein utilisation

Effects of vitamin D3 supplementation in gilthead seabream (Sparus aurata) juveniles fed diets high in plant based feedstuffs

Modern aquaculture feeds tend to contain lower levels of fish based ingredients, while increasing the content of plant ingredients. However, this may alter the vitamin profile of the feeds, leading to unbalanced vitamin supply. Requirements for several vitamins have been established for species such as carps and salmonids, but adequate levels for gilthead sea bream are yet unknown.publishedVersio

Backfat fatty acid evolution in swine fed diets high in either cis-monounsaturated, trans, or (n-3) fats

To evaluate the effects of dietary fats on the evolution of the fatty acid profile of swine backfat, 30 castrated Landrace x Duroc pigs averaging 26 kg were assigned three diets with 4% added pomace oil ( O ) , hydrogenated fat ( H ) , or linseed oil ( L ) . Subcutaneous fat samples were taken from biopsies at O, 17, 31, and 60 d, and at 24 h postmortem when pigs averaged 95 kg live weight at 82 d on trial. On d 17, saturated fatty acid ( SFA) content was 2% lower for the O diet than for H and L ( P < .089). There was a linear increase in SFA at a monthly rate of 2% in the three diets. The increase was mainly due to 18:0; palmitic acid percentages showed no variation. Pigs fed the O diet experienced exponential increases in monounsaturated fatty acids ( MUFA), especially until d 17 ( P < .001). In pigs fed the H or L diets, MUFA contents decreased at a monthly rate of 2.40%, and the same happened with oleic acid contents. Diets rich in ( n-3 ) ( L ) and trans-fatty acids ( H ) caused exponential increases in swine backfat contents of total ( n-3 ) and total trans, respectively. At d 31 ( P <.001), 72 to 73% of the maximum contents had been reached. Contents for 20:3(n-3), 20:5(n-3), and 22: 5( n-3) follow a pattern similar to that of their precursor 18:3(n-3), showing an exponential increase in pigs fed the L diet, and contents for H and O treatments were lower ( P < .001). The three diets caused a linear decrease in ( n-6 ) fatty acid contents throughout the 82-d trial

Musculoskeletal growth modulation in gilthead sea bream juveniles reared at high water temperature and fed with palm and rapeseed oils-based diets

The upward trend of seawater temperature has encouraged improving the knowledge of its consequences on fish, considering also the development of diets including vegetable ingredients as an approach to achieve a more sustainable aquaculture. This study aims to determine the effects on musculoskeletal growth of: (1) a high-water temperature of 28 °C (versus 21 °C) in gilthead sea bream juveniles (Sparus aurata) fed with a diet rich in palm oil and, (2) feeding the fish reared at 28 °C with two other diets containing rapeseed oil or an equilibrated combination of both vegetable oils. Somatic parameters and mRNA levels of growth hormone-insulin-like growth factors (GH-IGFs) axis-, osteogenic-, myogenic-, lipid metabolism- and oxidative stress-related genes in vertebra bone and/or white muscle are analyzed. Overall, the data indicate that high-water rearing temperature in this species leads to different adjustments through modulating the gene expression of members of the GH-IGFs axis (down-regulating igf-1, its receptors, and binding proteins) and also, to bone turnover (reducing the resorption-activity genes cathepsin K (ctsk) and matrix metalloproteinase-9 (mmp9)) to achieve harmonic musculoskeletal growth. Moreover, the combination of palm and rapeseed oils seems to be the most beneficial at high-water rearing temperature for both balanced somatic growth and muscular fatty acid uptake and oxidation

Genetically superior European sea bass (Dicentrarchus labrax) and nutritional innovations: Effects of functional feeds on fish immune response, disease resistance, and gut microbiota

The objective of this study was to determine if selected fish genotypes could benefit from the use of functional additives in novel aqua feed formulations to improve growth performance, gut microbiota, immune response, and disease resistance in fish. Two batches of juvenile European sea bass selected for high growth (HG; selected sires x selected dams), and wild types (WT; wild sires x selected females) were fed a “future diet” coated with three different functional additives for 12 weeks as follows: (i) 2 weeks with a high dose, followed by (ii) 10 weeks with a low dose. The functional additives tested were a mixture of probiotics (PROB), organic acids (ORG), and phytogens (PHYTO). A pathogen challenge test (Vibrio anguillarum) and a stress condition (overcrowding) were performed after each dose. At the end of the feeding experiment, fish from the HG group performed better than fish from the WT group in terms of body weight, relative growth, SGR, and DGI. The results of the two challenge tests performed after two weeks of high dose and ten weeks of low dose showed a significant effect of diet on fish survival. GALT-associated gene expression analysis revealed an interaction between the genotype and diet for il-1β in the distal gut. Finally, regarding the gut microbiota, discriminant analysis showed no clear separation between fish fed the future diet and those fed the same diet with experimental additives. Nevertheless, the relative abundance of certain taxa varied between experimental groups. For example, fish fed the ORG diet had higher relative abundance of Streptococcus in both genotypes, whereas fish fed the PHYTO diet had higher abundance of Lactobacillales. In contrast, fish fed PROB had lower abundance of Pseudomonas and Acinetobacter.The current study was supported by the EU Horizon 2020 AquaIMPACT (Genomic and nutritional innovations for genetically superior farmed fish to improve efficiency in European aquaculture), number: 818367.info:eu-repo/semantics/publishedVersio

Effects of calcium carbonate inclusion in low fishmeal diets on growth, gastrointestinal pH, digestive enzyme activity and gut bacterial community of European sea bass (Dicentrarchus labrax L.) juveniles

Fishmeal (FM) possesses one of the highest buffering capacities in comparison to most alternative vegetable aquafeed ingredients and its decreasing content in current formulations might affect the ideal gastrointestinal environment for digestive enzyme action and gut bacterial community of carnivorous fish species. A study was undertaken, therefore, to assess growth response, gastrointestinal pH, digestive enzyme activity and gut bacterial community of European sea bass (Dicentrarchus labrax L.) juveniles fed low FM diets (10% FM) with or without a feed buffering additive, calcium carbonate (FM10 + B and FM10, respectively) in comparison to a standard FM diet (20% FM, FM20). Three isonitrogenous and isolipidic extruded diets were fed to triplicate fish groups of 80 individuals (initial weight: 23 g) to overfeeding over 64 days. No significant differences due to low FM dietary levels were observed in final body weight, specific growth rate, feed intake, feed and protein efficiency. Low FM diet did not affect gastrointestinal pH in the stomach, anterior intestine, mid-intestine and hindgut at 0, 4, 8 and 12 hours post meal (hpm) while the inclusion of calcium carbonate in low FM diet seems to slightly increase the pH in the hindgut at 12 hpm. The absence of significant differences of pepsin, chymotrypsin, amylase and lipase activity suggests a comparable digestive efficiency among treatments although trypsin activity was slightly reduced in low FM diets after 4 hpm. Decreasing FM content seems to exert an effect on the overall gut bacterial community analysed by next-generation sequencing even if no significant effects on specific bacterial component were detected. The gut bacterial community in all the treatments was particularly rich in lactic acid bacteria such as Lactobacillus spp. which may provide important beneficial functions for the host and be associated with a healthy intestinal epithelium. According to the results, increasing the feed buffering capacity does not seem to improve digestive conditions while it is feasible to include 10% FM dietary level in practical formulation for European sea bass juveniles without negatively affecting growth, feed efficiency and digestive luminal conditions.info:eu-repo/semantics/publishedVersio

Hydroxytyrosol-rich extract from olive juice as an additive in gilthead sea bream juveniles fed a high-fat diet: Regulation of somatic growth.

The dietary inclusion of plant-based products in fish feeds formulation is required for the sustainable development of aquaculture. Moreover, considering functional diets, hydroxytyrosol, one of the major phenolic compounds found in olives (Olea europaea), has been identified as a potential candidate to be used in the aquafeeds industry due to its health promoting abilities. The aim of this study was to evaluate the effects of the inclusion of an olive juice extract rich in hydroxytyrosol as an additive (0.52 g HT/kg feed) in a high-fat (24% lipids) diet in gilthead sea bream (Sparus aurata) juveniles. Moreover, the experimental diets, with or without the extract, were administered daily at a standard (3% of total biomass in the tank) or restricted ration (40% reduction) for 8-9 weeks. Growth and biometric parameters, insulin-like growth factor 1 (IGF-1) plasma levels and growth hormone/IGF axis-, myogenic- and osteogenic-related genes expression in liver, white muscle and/or bone were analyzed. Moreover, in vitro cultures of vertebra bone-derived cells from fish fed the diets at a standard ration were performed at weeks 3 and 9 to explore the effects of hydroxytyrosol on osteoblasts development. Although neither body weight or any other biometric parameter were affected by diet composition after 4 or 8 weeks, the addition of the hydroxytyrosol-rich extract to the diet increased IGF-1 plasma levels, regardless of the ration regime, suggesting an anabolic condition. In muscle, the higher mRNA levels of the binding protein igfbp-5b and the myoblast fusion marker dock5 in fish fed with the hydroxytyrosol-rich diet suggested that this compound may have a role in muscle, inducing development and a better muscular condition. Furthermore in bone, increased osteogenic potential while delayed matrix mineralization after addition to the diet of the olive juice extract was supported by the upregulated expression of igf-1 and bmp4 and reduced transcript levels of osteopontin. Overall, this study provides new insights into the beneficial use of hydroxytyrosol as a dietary additive in gilthead sea bream functional diets to improve muscle-skeletal condition and, the aquaculture industry

Next-generation sequencing characterization of the gut bacterial community of gilthead sea bream (Sparus aurata, L.) fed low fishmeal based diets with increasing soybean meal levels

The present study was carried out to evaluate growth, gut histology and gut bacterial community of gilthead sea bream (Sparus aurata) fed with increasing dietary soybean meal (SBM) levels in a low fishmeal (FM) based diet, in comparison with a control diet. Five isoproteic and isolipidic experimental diets were formulated to contain increasing levels of SBM (0, 100, 200, and 300 g kg 121 named S0, S10, S20 and S30, respectively) with 150 g kg 121 of FM, and one control diet (C) without SBM and containing 350 g kg 121 of FM. Sixty sea bream (initial body weight 75.9 \ub1 1.9 g, n = 900) per tank were reared in a recirculation system at 23.0 \ub1 1.0 \ub0C and fed to satiation. The trial was run in triplicate and lasted 100 days. At the end of the trial fish fed the S30 diet showed a higher (P 64 0.05) specific growth rate (SGR) compared to S0 (SGR, 1.17 \ub1 0.03, 1.20 \ub1 0.01, 1.22 \ub1 0.01, 1.25 \ub1 0.01 and 1.21 \ub1 0.04 for S0, S10, S20, S30 and C, respectively), and a higher feed intake (FI) compared to S0, S10 and S20. Sea bream fed the C diet had a higher (P 64 0.05) FI compared to S0 (FI, 1.40 \ub1 0.01, 1.45 \ub1 0.01, 1.44 \ub1 0.03, 1.51 \ub1 0.03 and 1.46 \ub1 0.02 for S0, S10, S20, S30 and C, respectively). No significant differences in feed conversion rate, protein efficiency ratio, gross protein efficiency and gross lipid efficiency among the treatments were detected. No specific histopathological changes indicative of soy-induced enteritis were observed in the intestine of any fish examined. Gut bacterial community of the distal intestine content was analyzed by Next-Generation Sequencing. At the phylum level, the gut bacterial community was dominated by Firmicutes (relative abundance 71%), while the most represented family was Lactobacillaceae (26%). Even if no significant differences (P 64 0.05) in the gut bacterial community \u3b1 and \u3b2-diversity according to the different diets were detected, Cyanobacteria and Lactobacillaceae progressively increased from diet C to diet S30. In conclusion results of growth, nutrient utilization, gut histology and gut bacterial community indicate that SBM can be successfully incorporated up to a level of 300 g kg 121 with the inclusion of 150 g kg 121 of FM, without any deleterious effects on growth, protein utilization and gut health during the on-growing of sea bream