Fatty acid digestibility in gilthead sea bream fed diets containing native, re-esterified or acid vegetable oils.

Re-esterified vegetable oils are obtained from a chemical esterification reaction between vegetable acid oils and glycerol. Due to their properties, it is expected that they have a higher nutritive value than their corresponding acid oils and a better digestibility than their native counterparts. The aim of the present study was to determine the effect of reesterified oils with a different monoacylglycerol (MAG) and diacylglycerol (DAG) content, produced from palm or rapeseed, on fatty acid digestibility in gilthead sea bream (Sparus aurata). Triplicate groups of fish were fed nine experimental diets containing different oils during 28 days. For each source, four different types of oil were used: native, re-esterified low or high in MAG and DAG and acid. A commercial fish oil was used for the control diet. Diets containing re-esterified oils had better apparent digestibility coefficients (ADC) of total fatty acids than acid oil diets. Reesterified oils do not negatively affect apparent digestibility coefficients of fatty acids when compared to their corresponding native oils and could be incorporated as a source of energy in diets for gilthead sea bream. An improvement in digestibility compared to the native oil diet was only obtained in palm re-esterified oil high in MAG and DAG

Efecto de la inclusión de distintas fuentes de grasa en dietas para pollos broiler sobre el perfil lipídico de la carne, la grasa abdominal y la piel

Se realizó una prueba experimental con 600 pollos broiler de la estirpe comercial Arbor-Acres, alimentándoles con dietas suplementadas con un 8% de sebo (S) , aceite de palma (AP) y oleina de soja-girasol (OSG). Al final del periodo productivo, los animales, con 49 días de vida, fueron sacrificados en un matadero comercial, seleccionándose las canales de los 10 animales, de cada tratamiento, con el peso vivo más próximo al valor medio del correspondiente tratamiento, para su posterior dissección y toma de pechugas, muslos, y muestras de grasa abdominal y piel. Todas las muestras se conservaron a -20°C hasta la realización de los correspondientes análisis cromatográficos. Los animales que habían consumido la dieta suplementada con OSG mostraron, en los tejidos analizados, los niveles más altos de ácido linoleico (C18:2) así como un mayor grado de insaturación. Los tejidos de los animales alimentados con AP y S contenían mayores proporciones de ácido palmítico (C16:0) y ácido oleico (C18:l), respectivamente

Acid and re-esterified rapeseed oils as alternative vegetable oils rainbow trout diets: Effects on lipid digestibility and growth

The present study aimed at evaluating the effects of dietary acid and re-esterified rapeseed oils as alternatives to native vegetable oils (VO) on growth performance and feed utilization in rainbow trout. Acid oils are a free fatty acid (FFA)-rich by-product from the refining of VO and re-esterified oils are the final product of a chemical esterification process between acid oils and glycerol. Because re-esterified oils have a high content of mono- and diacylglycerols (MAG and DAG), known for being good emulsifiers, a higher nutritive value than that of the native and the acid oils might be expected. A 72-day feeding trial where triplicate groups of rainbow trout were fed eight experimental diets formulated to contain 15% of a native, a re-esterified and an acid rapeseed oil, in addition to a 5% of fish oil (FO), was carried out. Diets with the native or the re-esterified oils blended with the acid oil were also studied. A commercial fish oil was used for the control diet. Fish fed rapeseed acid and re-esterified oil diets (RA and RE, respectively) showed high fat and total fatty acid apparent digestibility coefficients (ADC) (RA: 90.5 ± 0.3%, RE: 92.5 ± 1.0% for total fat and RA: 95.7 ± 0.1%, RE: 95.8 ± 0.2% for total fatty acids). However, the lowest total fatty acid ADC was that obtained in animals fed RA, which was significantly lower (P b 0.05) than that of fish fed the rapeseed native oil diet (RN: 96.7 ± 0.1%). No significant differences in final weight were obtained between fish fed RA (375.9 ± 2.9 g) and RE (381.5 ± 11.1 g) and those fed RN (393.7 ± 6.1 g), even though both values were significantly lower (P b 0.05) than that of fish fed the control diet (411.1 ± 3.3 g). Nonetheless, fish fed diets including blends of the rapeseed acid and the re-esterified oils (RE/RA and RA/RE) had higher final weights (392.8 ± 4.4 and 394.6 ± 1.6, respectively) than those of RA and RE, although differences were not statistically significant. Furthermore, RA and RE diets did not produce relevant changes in plasma parameters or in the morphology of liver and intestine of fish. Therefore, the inclusion of rapeseed acid and re-esterified oils along with a 5% of FO in aqua feeds does not seem to have negative effects on fat and fatty acid digestibility, growth, plasma parameter or morphology of liver and intestine in rainbow trout. However, before recommending their use, further studies regarding their effects on the final composition and quality of fillets should be carried out. Statement of relevance: Re-esterified and acid rapeseed oils could be included in diets for rainbow trout as economically advantageous sources with no negative results in fat and fatty acid digestibility, plasma parameters and morphology of liver and intestine

Quality characteristics of fillets of rainbow trout fed acid or re-esterified rapeseed oils as dietary fat sources

Alternatives to the use of native vegetable oils (VO) as fish oil (FO) replacers in aqua feeds were evaluated. Acid oils are a free fatty acid (FFA)-rich by-product mainly from the refining of VO. Re-esterified oils are the final product of a chemical esterification reaction between acid oils and glycerol, and have less FFA and more monoand diacylglycerols (MAG and DAG), known for being good emulsifiers, than crude VO. Therefore, they could have a higher nutritive value than that of the native and acid oils. In two earlier studies in rainbow trout (Trullàs et al., 2015, 2016), diets including acid and/or re-esterified VO resulted in total fatty acid apparent digestibility coefficients above 95%. Moreover, no negative effects on growth, plasma biochemical parameters and morphology of tissues were observed when compared to the native oil diet. For all these reasons, the present study aimed at assessing their effects on the final quality of fillets of rainbow trout. Triplicate groups of rainbow trout were fed eight experimental diets containing 15% of different types of experimental rapeseed oils in addition to 5% of FO during 72 days. The experimental rapeseed oils were native (RNO), acid (RAO), re-esterified (REO), or blends (66% RN-33% RAO/33% RN-66% RAO or 66% REO-33% RAO/33% REO-66% RAO). Commercial FO was used for the control diet (F). The colorimetric analysis resulted in significant differences only in b* and C* in both fresh and thawed fillets, as well as in significant correlations between the colorimetric parameters among diets. For the total fat content, fillets of fish fed the control diet obtained the highest values, which were higher than those of fish fed diets containing RNO and the blend 66% REO-33% RAO. No differences in texture, liquid holding capacity, and TBARS were found among fillets of fish fed the different diets. Regarding tocopherol concentrations in fillets, α-tocopherol was significantly higher (P < 0.05) in fillets of fish fed the control diet than in those fed RA/RE, while β + γ-tocopherol was significantly lower in fillets of fish fed C than in the rest. Even though the aforementioned differences were found, they did not seem to be relevant concerning the final quality of fille

A primary phosphorus-deficient skeletal phenotype in juvenile Atlantic salmon Salmo salar : the uncoupling of bone formation and mineralization

To understand the effect of low dietary phosphorus (P) intake on the vertebral column of Atlantic salmon Salmo salar, a primary P deficiency was induced in post-smolts. The dietary P provision was reduced by 50% for a period of 10 weeks under controlled conditions. The animal's skeleton was subsequently analysed by radiology, histological examination, histochemical detection of minerals in bones and scales and chemical mineral analysis. This is the first account of how a primary P deficiency affects the skeleton in S. salar at the cellular and at the micro-anatomical level. Animals that received the P-deficient diet displayed known signs of P deficiency including reduced growth and soft, pliable opercula. Bone and scale mineral content decreased by c. 50%. On radiographs, vertebral bodies appear small, undersized and with enlarged intervertebral spaces. Contrary to the X-ray-based diagnosis, the histological examination revealed that vertebral bodies had a regular size and regular internal bone structures; intervertebral spaces were not enlarged. Bone matrix formation was continuous and uninterrupted, albeit without traces of mineralization. Likewise, scale growth continues with regular annuli formation, but new scale matrix remains without minerals. The 10 week long experiment generated a homogeneous osteomalacia of vertebral bodies without apparent induction of skeletal malformations. The experiment shows that bone formation and bone mineralization are, to a large degree, independent processes in the fish examined. Therefore, a deficit in mineralization must not be the only cause of the alterations of the vertebral bone structure observed in farmed S. salar. It is discussed how the observed uncoupling of bone formation and mineralization helps to better diagnose, understand and prevent P deficiency-related malformations in farmed S. salar

Nutrition of greater amberjack (Seriola dumerili): Highlights at different stages of the life cycle.

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Effects of feeding low fishmeal diets with increasing soybean meal levels on growth, gut histology and plasma biochemistry of sea bass

The aquaculture industry depends upon the development of sustainable protein sources to replace fishmeal (FM) in aquafeeds and the products derived from soybeans are some of the most studied plant feedstuffs. A key area of investigation for continuing to improve modern aquafeeds includes the evaluation of varying proportions and combinations of plant ingredients to identify mixtures that are more efficiently utilized by the fish. This study investigated the effects of increasing soybean meal (SBM) by replacing a mix of plant ingredients in low FM (20%) diets on growth, blood biochemistry profile and gut histology on European sea bass. Five isonitrogenous and isolipidic experimental diets were formulated: four diets containing increasing SBM levels (0, 10, 20 and 30%; 0SBM, 10SBM, 20SBM and 30SBM, respectively) with a low content of FM (20%) and one control diet (0% SBM; 35% FM). Diets containing SBM brought to comparable performance and protein utilization, while 0SBM had negative impact on feed conversion rate and protein utilization. Blood parameters suggested an optimal nutritional status under all feeding treatments, even though slightly decreased values were reported at increasing dietary SBM. Histology examination did not show any changes indicative of soy-induced enteritis. We can conclude that for European sea bass: (i) different blends of plant protein did not affect feed intake despite the 20% FM dietary level; (ii) the inclusion of SBM maintains optimal growth and feed utilization in low FM diets; (iii) blood biochemistry profile showed a good nutritional status under all feeding regimes; (iv) no evidence of soy-induced enteritis was reported in any group fed low FM diets. For formulation of practical diets in on-growing of European sea bass, SBM up to 30% can be successfully incorporated into feeds containing low FM inclusion

Genotype x nutrition interactions in European sea bass (Dicentrarchus labrax): effects on gut health and intestinal microbiota

One of the main objectives of the present study was an effective replacement of dietary fishmeal/fish oil (FM/FO) by new raw materials without negatively affecting European sea bass (Dicentrarchus labrax) performance and health status within a selection breeding context. The genomic selection of this species is still in its infancy if compared to salmonids and in particular, the role of D.labrax genome in shaping the gut microbiome, has been scarcely investigated. Wildtype (WT) and selected (GS) sea bass were fed with two diets: a control (20% FM/ 5–9% FO), and a “future” (F) diet, in which FM was decreased to 10% being replaced by poultry meal, whereas FO was completely replaced by a blend of rapeseed, poultry, and algae oils. The morphological evaluation of the intestine revealed a well-organized folding pattern and a conserved gut epithelial barrier for all fish groups. Despite a basal level of inflammation in the proximal intestine of WT fish, no differences were observed neither in the morphometric characteristics of goblet cells nor in the expression of GALT-related genes in response to fish genotype or diet. At distal intestine, WT fish showed a higher inflammatory status and larger goblet cells than GS fish and within the same genotype, fish fed the F diet had in general larger goblet cells. In distal intestine, a significant effect was found on the expression of 3 out of 7 target GALT genes. In particular, the expression of cytokines il-1β, tnf-α, and il-10 was different, showing an interaction effect diet x genotype. Diet had a lower influence upon gut bacterial composition than genotype. Indeed, regardless of the diet, WT fish showed higher species richness than GS genotype and this could be a direct consequence of selective breeding for multiple traits selection including growth, external morphology for lower abdominal fat deposition and adaptation to multiple and successive feed sources and composition across generations of selection. Furthermore, the gut microbiota of GS fish shared a reduced individual variability, indicating an enhanced capacity to cope with changes in diet composition. The less changes of GS sea bass at the level of gut bacterial composition in cumulating data collected with the feeds, demonstrate a capacity to reshape their microbiota thus better adapting to the diet, but with no negative impact on their growth performances, and even a better growth. A significant genotype effect was found for specific bacterial taxa, such as Paracoccus genus and other genera belonging to Moraxellaceae family, which were enriched in WT fish, regardless of the diet. Interestingly, the relative abundance of Paracoccus genus was positively correlated with higher proinflammatory cytokine il-1β expression found in distal intestine of wildtype sea bass

Nutritional innovations in superior European sea bass (Dicentrarchus labrax) genotypes: implications on fish performance and feed utilization.

The sustainable development of the aquaculture industry relies on the use of alternative conventional and emergent raw materials that contributes to a circular economy and to reduce the dependency on fish meals and fish oils coming from oceanic fish populations. Additionally, the genetic selection of farmed fish that can display higher growth and feed utilization when fed alternative feeds, is pointed out to be a complementary valuable tool to facilitate the implementation of circular economy approaches. The main purpose of the present study was to determine the effectiveness of genetic selection for growth in European sea bass, in response to a challenge with an alternative diet that aimed to partially replaced fishmeal (FM) by poultry meal (PM) and totally replace fish oil (FO) by a blend of poultry oil (PO) with a novel microalgae oil. The two families of fish juveniles were obtained by in vitro fertilization of selected for a multi-trait including high growth (genetically selected, GS) or nonselected (wild type, WT) broodstocks and then were nutritionally challenged with a control diet that mirrored a standard commercial diet with fishmeal (20%) and fish oil (7%), or a Future diet that partially replaced the FM by PM and totally replaced the FO by a blend of rapeseed oil, PO, and a novel DHA rich-algal oil. From the second month of feeding until the end of the trial, European sea bass that was selected since for 7 generations performed better in terms of growth than the wild-type genotype, possibly related with an apparent favored feed and nutrient utilization. Furthermore, selection decreased the perivisceral fat and increased the nutritional value of flesh by increasing DHA (in g/ 100 g flesh) and ARA contents. In contrast, the dietary treatment showed little effect on fish growth performance, denoting the successful partial replacement of FM by PM and the total replacement of FO by a blend of poultry oil and an emergent microalgal oil. However, Future diet tended to reduce the ADCs of some amino acids, as well as showed an additive effect to genotype in increasing the n-3 PUFA of flesh. Altogether, our data demonstrate that multi-trait genetic selection of European sea bass improve fish plasticity to cope with the variations of ingredients in alternative feeds with low FM/FO

A quantitative analysis of gilthead seabream (Sparus aurata) juvenile dentition as a tool to assess the effect of diet

Gilthead seabream (Sparus aurata Linnaeus, 1758 (Perciformes, Sparidae)) is an important aquaculture species in the Mediterranean Sea basin. Yet, quantitative data on its dentition under standard farming conditions are currently lacking. Furthermore, it is unknown if the dentition can adapt to food of different sizes. Here, we describe the lower jaw dentition of juvenile S. aurata fed a standard pellet size (4 mm) and present a detailed analysis of 11 representative teeth. Overall, the number of teeth showed large individual variation, but it was not significantly related to fish length. Considerable left–right differences were observed, without clear side dominance. We also assessed the influence of feeding S. aurata a smaller (2 mm) or larger (6 mm) pellet size. Four months of feeding with different pellet sizes did not cause detectable differences in total tooth number on the dentaries at the time of harvest, nor in size of the teeth assumed to be most relevant in food processing. If and how different pellet sizes may nevertheless affect digestion, and eventually fish health, is subject for further studies