Essential Fatty Acid Requirements Research Articles

Influence of broodstock nutrition on egg quality and fatty acid composition in California Yellowtail

AbstractObjectiveCalifornia Yellowtail (CYT) Seriola dorsalis are continuous spawners and rely entirely on their diet to supply nutrients like fatty acids (FAs) to their eggs to support early development. The objective of this study was to determine whether commercial diets could replace a diet consisting of fresh fishery products (FFP‐D) without compromising egg quality and biochemical composition, specifically FAs.MethodsIn 2017, one broodstock group (one female and two males) was fed a formulated reference feed (REF‐D; Bio‐Oregon). This pilot experiment showed that it was possible for a minimum of one female and two male broodfish to spawn repeatedly in a tank, a finding that led to a replicated diet experiment during 2018 in which 18 CYT broodfish were divided into six replicate tanks, with one female and two males per tank. Three tanks were fed the FFP‐D as a control, and three tanks were fed a commercial diet (COM‐D; Breed‐M, INVE). For each spawning event, egg quality metrics were collected, along with samples for FA analysis.ResultThe 2017 REF‐D treatment produced eggs that met arachidonic acid (ARA) and eicosapentaenoic acid (EPA) requirements and had egg metrics comparable to those obtained from the FFP‐D, with higher viability and average batch fecundity. However, the REF‐D treatment had insufficient docosahexaenoic acid (DHA) and no tank replicates. The 2018 COM‐D treatment produced eggs with large egg and oil diameters and met ARA and EPA requirements but was associated with very poor spawning and hatch success and had insufficient DHA levels. The FFP‐D treatment produced below‐average viability and batch fecundity rates and was unable to meet most essential FA requirements, but it yielded the greatest number of spawning events.ConclusionNone of the experimental treatments, including the control, was able to fully meet the nutritional requirements of CYT broodstock. These results reveal crucial data about current CYT broodstock diets that can facilitate future research for developing nutritionally complete diets, especially in terms of essential FAs.

오메가-6 대 오메가-3 비율의 기능의학적 의의

Omega-6 fatty acids and omega-3 fatty acids are essential fatty acids, which should be consumed and supplemented for the functioning of our bodies. The absolute essential fatty acids are linolenic acid and alpha-linolenic acid. However, considering the low conversion rate in vivo and their enzyme activity depending on individual genotype and disease condition, direct intake of gamma-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid is important. Requirements for essential fatty acids may vary from person to person. This means that the omega-6 and omega-3 fatty acid pathways compete to use the same enzymes, the modern Western diet focuses on omega-6 fats, and stress, aging, menopause, and relative deficiencies cause increased inflammation and decreased enzyme activity. The important thing is to consume or supplement fatty acids in a balanced manner rather than supplementing just one kind of 'healthy' fatty acid. Fatty acid imbalance is not a single problem but is complex and organically intertwined, so it usually causes complex problems. Excessive supplementation of one fatty acid can worsen the deficiency of other fatty acids, so wisdom is needed to supplement by checking blood omega-3 index and clinical evidence that can provide appropriate evidence.

Predicted essential fatty acid intakes for a group of dairy cows also apply at individual animal level

The ruminant requirements for essential fatty acids (EFAs), particularly linoleic acid (LA) and alpha-linolenic acid (ALA), have not been fully determined, although evidence suggests that an adequate supply of polyunsaturated fatty acids (FAs) could improve immunity and reproduction in transition cows. In previous studies, we predicted EFA intake for a group of cows based on animal characteristics and milk EFA secretions. However, to support precision livestock feeding, we need to match the nutrient requirements and intakes of each cow as closely as possible. Our group-level predictions may not be accurate enough to estimate the EFA intake of an individual cow, due to inter-individual variations in EFA digestion and metabolism related to differences in feed intake, intake patterns, and the composition and functioning of the rumen microbiota. To address this issue, here we set out to establish specific equations that predict EFA intake for an individual cow based on the difference (i.e. the residuals) between observed EFA intake and the predicted EFA intake based on our group-level equations. We studied a database of individual dairy cows (26 experiments; 503 datapoints from three research teams) and we predicted the residuals from (1) dietary and animal-related factors (i.e. full predictions) and (2) animal-related factors only (i.e. field predictions), which are considered more field-amenable. The variance of predicted LA and log ALA intake was explained to 68% by observed LA intake and 66% by observed log ALA intake, respectively. The residuals of LA intake were predicted by dietary ALA content, total FA intake, BW, milk yield and fat content in full predictions, and by BW, feeding level, milk yield and fat content, and sum of milk C4:0 to C14:0 FA in field predictions. The log residuals of ALA intake were predicted by dietary NDF and total FA contents, NDF intake, BW, milk protein, LA and ALA contents, and fat yield in full predictions, and by BW, DM intake, milk LA and ALA contents, and fat yield in field predictions. The field predictions showed a moderate loss of accuracy compared to full predictions based on RMSE of prediction (from 38 to 54 g/d for LA and from 0.090 to 0.12 log (g/d) for ALA). This work is the first to predict the EFA intake of an individual cow based on previously established group-level predictions of EFA intake adjusted for dietary and animal-related factors.

The importance of essential fatty acids and their ratios in aquafeeds to enhance salmonid production, welfare, and human health

Long chain polyunsaturated fatty acids (LC-PUFA), namely those from omega-3 (n-3) and omega-6 (n-6) families, are paramount for both fish and human nutrition. Some of these biomolecules cannot be synthesized de novo and must be acquired through the diet, being termed dietary essential fatty acids (EFA). Fish requirements for EFA have traditionally been met through the incorporation of fish oil (FO) in the formulation of aquafeeds. However, with limited supply of FO the aquaculture industry is searching for additional sustainable sources of LC-PUFA. This has significantly shifted the type of ingredients used in aquafeed formulation, namely vegetable oils (VO) deficient in long-chain omega-3, often resulting in imbalanced levels and ratios of fatty acid classes. Such imbalances can negatively affect fish performance and welfare, as well as the levels of health promoting omega-3 LC-PUFA present in fish fillets. Given the relevance that salmonid aquaculture plays in global fish production (principally Atlantic salmon, Salmo salar), as well as its growing role as a source of dietary health promoting omega-3 LC-PUFA for humans, the present review summarizes the scientific knowledge available to date on the dietary requirements for LC-PUFA by salmonids and humans. We discuss the implications of using imbalanced aquafeed formulations upon fish performance and welfare, as well as the subsequent consequences for human nutrition, along with current efforts to replace FO by alternative ingredients such as algal oil (AO) that can safeguard high-quality salmonid products for human consumption.

Essential fatty acid requirement of juvenile meagre (Argyrosomus regius)

Meagre (Argyrosomus regius) is a fast-growing marine teleost and a promising candidate for the diversification of the Mediterranean aquaculture industry. Information on specific dietary requirements is necessary to improve the competitiveness of meagre farming. While the essential fatty acids (EFA) requirement of meagre fingerlings was previously estimated, knowledge regarding the EFA requirement of on-growing meagre juveniles is still lacking. To assess the EFA requirement of juvenile meagre, six isolipidic, isoproteic, semi-purified diets with different levels of n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) contents 0.0%, 0.3%, 0.6%, 0.9%, 1.2%, and 1.5% of diet dry matter (DM) were formulated and fed three times daily to triplicate groups of juvenile meagres of 35.6 ± 0.3 g for twelve weeks. Growth rates, whole body composition and fatty acid profile, liver lipid content as well as fatty acid profiles were assessed. In addition, the incidence of hepatic steatosis and granulomatosis was evaluated. Juvenile meagre fed the 0.0% n-3 LC-PUFA diet showed significantly lower growth and final body weight compared to all other treatments. There was an increase in growth of meagre with increasing dietary n-3 LC-PUFA levels and weight gain plateaued at levels above 0.9% n-3 LC-PUFA. Occurrence of granulomas examined in the liver supported the data on growth as the hepatic granulomatosis incidence in the groups fed <0.9% n-3 LC-PUFA were greater compared to fish fed diets containing higher levels of n-3 LC-PUFA. The findings of this study showed that the dietary n-3 LC-PUFA requirement of juvenile meagre for optimal growth and liver health status lays between 0.7 and 0.8% of the dietary dry matter.

Effect of Dietary Lipid Sources and Their Combinations on Growth and Fatty Acid Composition of Milkfish (Chanos chanos) Larvae

Background: The success of larval rearing is greatly influenced by first feeding regimes and the nutritional quality of weaning diets, with dietary lipids being recognized as one of the most important nutritional factors that affect larval growth and survival. Reports are scanty on milkfish larval nutrition and growth and survival unlike other marine species. Methods: In this investigation during 2020, five larval diets were prepared with 40 g kg-1 of entirely fish oil (F4), corn oil (C4) or fish oil and corn oil in 3:1 (F3C1), 2:2 (F2C2) and 1:3 (F1C3) ratios. Each diet was fed to triplicate groups of milkfish larvae (45 mg) in a flow-through rearing system for 42 days. Result: A growth indices were highest in the F3C1 group, followed by F2C2, F4 and other dietary treatments. The whole-body fatty acid profile was found to change significantly with increasing fish oil replacement with corn oil, i.e., the n-3 polyunsaturated and saturated fatty acid proportions decreased linearly, while the n-6 polyunsaturated fatty acids content increased. Overall, this study reveals that growth and survival of milkfish is dependent on dietary lipid source or combinations that meet the essential fatty acid requirements during the early life stages.

The Importance of Fatty Acid Precision Nutrition: Effects of Dietary Fatty Acid Composition on Growth, Hepatic Metabolite, and Intestinal Microbiota in Marine Teleost Trachinotus ovatus.

Our recent study demonstrated that diet with blend oil (named BO1) as lipid, which is designed on the base of essential fatty acid requirement of Trachinotus ovatus, achieved good performance. Here, to confirm its effect and investigate the mechanism, three isonitrogenous (45%) and isolipidic (13%) diets (D1-D3) only differing in dietary lipids, which were, respectively, fish oil (FO), BO1, and blend oil 2 (BO2) consisting of FO and soybean oil at 2 : 3, were formulated and used to feed the T. ovatus juveniles (average initial weight: 7.65 g) for 9 weeks. The results showed that the weight gain rate of fish fed D2 was higher than that of fish fed D3 (P < 0.05) and had no significant difference from that of fish fed D1 (P > 0.05). Correspondingly, compared with the D3 group, fish of the D2 group exhibited better oxidative stress parameters such as lower serum malondialdehyde content and inflammatory indexes in the liver such as the lower expression level of genes encoding four interleukin proteins and tumor necrosis factor α, as well as higher hepatic immune-related metabolites such as valine, gamma-aminobutyric acid, pyrrole-2-carboxylic acid, tyramine, l-targinine, p-synephrine, and butyric acid (P < 0.05). Furthermore, the intestinal probiotic (Bacillus) proportion was significantly higher, while the pathogenic bacteria (Mycoplasma) proportion was significantly lower in the D2 group than that in the D3 group (P < 0.05). The main differential fatty acids of diet D2 were close to those of D1, while the levels of linoleic acid and n-6 PUFA, as well as the ratio of DHA/EPA of D3, were higher than those of D1 and D2. These results indicated that the better performance of D2 such as enhancing growth, reducing oxidative stress, and improving immune responses and intestinal microbial communities in T. ovatus may be mainly due to the good fatty acid composition of BO1, which indicated the importance of fatty acid precision nutrition.

Reproductive management of the mugilid Liza aurata and characterization of proximate and fatty acid composition of broodstock tissues and spawnings

The golden grey mullet (Liza aurata) is a promising species for aquaculture's sustainable expansion. However, the lack of sustainable juvenile provision, mainly related to the lack of reproductive control, is one of the most significant bottlenecks for further expanding the culture of this species. In many cases, mullet broodstock management needs the application of hormone treatments to induce gonadal maturation or spawning. However, no works are directly related to the broodstock collection, acclimation, and reproductive management of Liza aurata. On the other hand, the knowledge of essential fatty acids (EFA) requirements and mobilization patterns by the broodstock is a first step to designing appropriate feeding protocols and formulas, which are crucial for the success of reproduction and larval development.For these reasons, this study aimed 1) to describe for the first time the reproductive management of Liza aurata broodstock under controlled conditions and 2) to offer a first approach to the reproductive lipid metabolism of the former species.A selection of 22 Liza aurata broodstock from wild origin was acclimated in open seawater conditions. Additionally, the proximate and fatty acid composition of body tissues (gonads, liver, and muscle) of the initial wild population were evaluated, to be later compared with the profile of the eggs obtained after one year from the selected broodstock, for the first time described under cultured conditions.The results highlighted the feasibility for the obtention of natural spawnings from broodstock with a mean weight of 787 g and 604 g (females and males, respectively), at a sex ratio of 2:1 (females/males), under natural photoperiod and marine water conditions with temperatures decreasing from 20.4 ± 0.3 °C to 18.8 ± 0.4 °C.On the other hand, it was evidenced the crucial role of HUFA (highly unsaturated fatty acids) precursors for the gonadal development of Liza aurata, primarily for females. Additionally, the wild males' gonads presented a remarkable high content of HUFA, predominantly DHA (docosahexaenoic acid) (34% of the total fatty acids). In the eggs, significant variations appeared under captivity conditions, with lower levels of ARA (arachidonic acid) and EPA (eicosapentaenoic acid) and higher EPA/ARA and DHA/ARA ratios than the wild female gonad. Additionally, it was evidenced the significant role of the liver as a physiological reservoir of HUFA, which seem to be mobilized to the gonad during the maturation process.Present results may help obtain a better insight to adjust broodstock management conditions and feeds, contributing to a more sustainable aquaculture growth.

Metabolism of linoleic and linolenic acids in muscle cells of two freshwater fish with n-3 or n-6 fatty acid requirements

Different fish species have specific requirements for essential fatty acids (EFAs). However, it is not well known whether cellular EFAs metabolism patterns among fish species are related to their differences in EFA requirements. In the present study, we used primary muscle cells from grass carp (GCM) and Nile tilapia (NTM), which has specific requirement of n-3 and n-6 EFA, respectively, to compare the fatty acids uptake, β-oxidation and esterification towards [1-14C]-labeled linoleic acid (LA, 18:2n-6) and linolenic acid (LNA, 18:3n-3). The results showed that the uptake rate of LNA was significantly (P < 0.05) higher than LA in GCM, but lower than LA in NTM. Total mitochondrial and peroxisomal β-oxidation efficiencies for LA were also significantly higher than those for LNA in GCM, while the opposite trend was observed in NTM. In GCM, the esterification of LNA into triacylglycerol (TG) was significantly lower than that of LA, but higher LNA esterification into phosphatidylcholine (PC) than LA was observed. However, the significantly higher LA esterification into TG and PC was observed in NTM. Additionally, LNA significantly upregulated the expressions of the genes related to lipid transportation, while significantly downregulated the expressions of the genes related to lipid catabolism in GCM. However, in NTM, the LA significantly upregulated the expressions of the genes related to lipid transportation, but did not change the expressions of the genes related to lipid catabolism and lipogenesis. In conclusion, GCM had specific preference to uptake and esterify LNA and tends to breakdown LA, while NTM preferred to uptake and esterify LA and tended to breakdown LNA. These differences are in accordance with the specific EFA requirements of grass carp and Nile tilapia. Our present study provides new information for understanding the specific EFA requirements of different fish species from the perspective of cellular EFAs metabolism.

Selection for high growth improves reproductive performance of gilthead seabream Sparus aurata under mass spawning conditions, regardless of the dietary lipid source

Genetic selection programmes in gilthead seabream mainly focus on traits related to growth, disease resistance, skeletal anomalies, or fillet quality. However, the effect of selection for growth on the reproductive performance of seabream broodstock has not received much attention. The present study aimed to determine the effect of selection for growth traits, high (HG) or low (LG) growth, and broodstock feeding with fish oil (FO diet) or rapeseed oil (RO diet) as main lipid sources, on reproductive performance of gilthead seabream. For the first part of the spawning season (Phase I) HG and LG broodstock were fed a commercial diet and the HG broodstock produced a higher number of larvae and higher viable eggs, hatching and larval survival rates than LG broodstock, affecting egg fatty acid profiles. For the second part of the study (Phase II) broodstock were fed one of the two diets containing FO or RO. Fecundity in terms of viable eggs, hatchlings, and larvae produced, as well as fertilization rates, were improved in HG broodstock. Some fatty acids such as 18:0, 20:2n-6, 20:3n-3 or EPA/ARA were also affected by the growth selection. According to the two-way ANOVA analysis, feeding the RO diet did not significantly affect fecundity parameters, but slightly reduced fertilization and hatching rates in HG broodstock. Nevertheless, HG broodstock showed better spawning quality parameters than LG broodstock, even when they were fed the RO diet. Egg fatty acid profiles reflected diet composition, although DHA contents were not affected. In conclusion, broodstock selected for high growth had a positive effect on broodstock performance, and FO replacement by RO did not markedly affect reproduction providing that fatty acid contents were sufficient to fulfill the essential fatty acid requirements of gilthead seabream broodstock.

A comparison of regression models for defining EPA + DHA requirements using the gilthead seabream (Sparus aurata) as a model species

Carnivorous marine fish species such as gilthead seabream (Sparus aurata) require dietary eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids for optimal growth and wellbeing. The rapid growth of global aquaculture, along with increased proportions of dietary oil to increase growth rate of farmed fish, has meant that the supply of marine oils used in aquafeeds has become limited. The shortfall has been satisfied by using vegetable oils that lack EPA and DHA and, therefore, EFA (essential fatty acid) requirements of juvenile marine fish require reassessment. A dietary trial was carried out with gilthead seabream (~25 g) that were fed diets with six EPA + DHA levels ranging from 0.2% - 3.2% diet as fed. For each pellet size, the biometric data (weight gain, daily growth index and feed conversion ratio) were analysed by four different regression strategies, namely split linear, quadratic, the Gompertz function, and the four-parameter logistic function. Over the whole experimental period (two pellet sizes) data suggested the current published requirement (1% of diet) was low and should be increased to at least 1.2%. However, when the first pellet size for fish of 25–80 g was considered, the apparent requirement was at least 1.4% of diet. This demonstrated in a single trial that EFA requirement was a function of fish mass, decreasing as the fish grows. If FCR is considered, the requirement may be as high as 2%. The suitability of different regression models varied, as the data for the first pellet was best fit by curves but, over both pellet sizes, the split linear fit the data best. For asymptotic models (Gompertz and four-parameter logistic functions), a novel way of defining the requirement was presented, the “elbow” calculation as a method to bisect an asymptotic function. Therefore, using the raw data, we illustrate how a range of regression approaches could be explored when determining nutrient requirement estimates as no single model was an ideal fit for all response curves.

Complementary Foods and Milk-Based Formulas Provide Excess Protein but Suboptimal Key Micronutrients and Essential Fatty Acids in the Intakes of Infants and Toddlers from Urban Settings in Malaysia.

This study determined the intakes of complementary foods (CFs) and milk-based formulas (MFs) by a total of 119 subjects aged 6–23.9 months from urban day care centers. Dietary intakes were assessed using two-day weighed food records. Intake adequacy of energy and nutrients was compared to the Recommended Nutrient Intakes (RNI) for Malaysia. The most commonly consumed CFs were cereals (rice, noodles, bread). The subjects derived approximately half of their energy requirements (kcals) from CFs (57 ± 35%) and MFs (56 ± 31%). Protein intake was in excess of their RNI requirements, from both CFs (145 ± 72%) and MFs (133 ± 88%). Main sources of protein included meat, dairy products, and western fast food. Intake of CFs provided less than the RNI requirements for vitamin A, thiamine, riboflavin, folate, vitamin C, calcium, iron, and zinc. Neither CF nor MF intake met the Adequate Intake (AI) requirements for essential fatty acids. These findings indicate imbalances in the dietary intake of the subjects that may have adverse health implications, including increased risk of rapid weight gain from excess protein intake, and linear growth faltering and intellectual impairment from multiple micronutrient deficiencies. Interventions are needed to improve child feeding knowledge and practices among parents and child care providers.

Validity of Random Triglyceride Levels in Infants Receiving Parenteral Nutrition.

Background: Intravenous lipid emulsions (IL) are an important part of parenteral nutrition (PN) to meet essential fatty acid (EFA) requirements and metabolic demands of neonates and preterm infants. Some critically-ill neonates may not metabolize IL effectively which can lead to hypertriglyceridemia. Risks associated with this include increased pulmonary vascular resistance, displaced bilirubins, and platelet or macrophage dysfunction. Serum triglyceride (TG) concentration is used as a marker for lipid tolerance and predictor of potential complications involved with IL administration, but the clinical significance of this is still debated. Management of TG levels with regard to timing of laboratory tests, the ideal goal range, and duration of infusion of IL varies across institutions and is not standardized.Methods: Single-center, retrospective study of newborn infants receiving parenteral nutrition (PN). Fasting and non-fasting TG levels were drawn during the same lipid infusion of 2–3g/kg/day. The primary outcome was the difference between fasting and non-fasting TG levels. Statistical assessment of continuous data was done with student t-test and nominal data was evaluated using X2-test and logistic regression.Results: Forty infants were included with mean gestational age at birth of 29.5 ± 3.4 weeks and mean birth weight of 1.3 ± 0.5 kg. Mean time between lab draws while on same IL dose was 11.6 ± 0.2 h with resulting mean fasting and non-fasting (random) TG levels 82 ± 40 mg/dL (95% CI 68.4, 97.6) and 101 ± 40 mg/dL (95% CI 88.5, 115.8), respectively. Mean difference between TG levels during lipid-free interval and during infusion was −18.6 ± 51.2 mg/dL (95% CI −35.0, −2.3; p = 0.03).Conclusion: We concluded there is no difference in the management of IL, when TG level was drawn randomly or as fasting sample. Obtaining TG level during routine lab draws is appropriate. We extrapolated that the administration of IL over 24 h will not interfere with TG level.

The Malaysian Mahseer, Tor tambroides possess all required biosynthesis enzymes for the conversion of C18 polyunsaturated fatty acids to long-chain polyunsaturated fatty acids

The Malaysian mahseer (Tor tambroides) is an iconic and highly-priced freshwater large cyprinid with a natural dietary preference towards riverine fruits. Previous works indicate that dietary C18 polyunsaturated fatty acids can fulfill mahseer's essential fatty acid requirements. Given the need to reduce the use of fish meal and fish oil in aquafeed, there is considerable interest to sustain healthy levels of the beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in farmed fish. A prerequisite for a functional LC-PUFA biosynthesis pathway is an entire repertoire of desaturase (Fads) and elongase (Elovl) enzymes required for specific steps along the path. We showed here the presence of a Fads2 and two elongases, Elovl5 and Elovl2, in mahseer. These enzymes function collectively to convert C18 PUFA to the C20 LC-PUFA through Δ6 and Δ5 desaturation processes working in tandem with the Elovl5 elongation activities. Subsequently, further conversion to docosahexaenoic acid (DHA; 22:6n-3) involves Δ6 desaturation and Elovl2 and Elovl5. These enzymes displayed a typical expression pattern of freshwater teleost at the mRNA level, with significant transcripts in liver, intestine, and brain tissues. Under limited dietary LC-PUFA intakes, the expression of these genes in the liver was elevated. Tissue fatty acid composition also suggests the conversion of dietary α-linolenic acid (ALA; 18:3n-3) and linoleic acid (LA; 18:2n-6) to their respective LC-PUFA for deposition in brain and muscle tissues. Although the highest concentration of n-3 LC-PUFA is obtained using fish oil-based diet, our results showed considerable accumulation of EPA and DHA with dietary ALA provision. Taken together, we show the existence of complete machinery for the biosynthesis of LC-PUFA from C18 PUFA in mahseer and validates the mahseer's capacity to utilize dietary vegetable oils (VO) both growth and n-3 LC-PUFA deposition.

Essential Fatty Acid Requirements in Tropical and Cold-Water Marine Fish Larvae and Juveniles

To improve survival at early developmental stages (larvae and juveniles) of captive fish species, essential nutrients [i.e., essential fatty acids (EFA)] need to be identified. The physiological needs are likely to be different among species, particularly among those using different thermal habitats, because lipids are largely used to maintain cell membrane integrity (homeoviscous adaptation) in fishes. This review paper will focus on currently published research and the main results from our laboratories regarding optimum qualitative EFA requirements during larval and early juvenile stages in a warm-water marine species, the Florida pompano (Trachinotus carolinus), and a cold-water marine species, the winter flounder (Pseudopleuronectes americanus). To identify the qualitative optimal EFA requirements, we calculated the ratio of certain fatty acids (FA) in larval or early juvenile tissues to total FA present in the diet. This ratio indicates whether a specific FA from prey is selectively incorporated by larvae and juveniles. Overall, we found that young larvae from both cold- and warm-water species have greater demands for n-3 and n-6 highly unsaturated fatty acids (HUFA) than do larvae at weaning stages. However, the qualitative EFA requirements of the cold-water species at all early developmental stages were higher than those of the warm-water species. Enriched rotifer diets provided satisfactory amounts of omega 3 and omega 6 in Florida pompano, with small selective retention for docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA), suggesting a potential minor diet deficiency in these EFA. There were higher deficiencies in the cold-water species fed enriched rotifers, as demonstrated by the higher selective retentions of all EFA (DHA, EPA, and ARA), with the exception of larvae fed with copepods. The physiological needs in EFA for juvenile development seemed to be better met for both species when they were fed micro pellets. From the beginning of settlement and in young juveniles, qualitative values of 12% DHA, 10% EPA, 5% ARA, and 40% PUFA of total FA seem to be required for winter flounder juvenile development. In Florida pompano, these requirements could be met until larger juvenile stages, with 15% DHA, 3% EPA, 2% ARA, 2% DPA, and total PUFA below 30% of total FA. This review was done to aid future research aiming to develop nutritionally balanced microdiets or live-prey enrichment diets to satisfy the physiological requirements of captive tropical and cold-water marine fish species.

Does Consumption of Baker's Yeast (Saccharomyces cerevisiae) by Black Soldier Fly (Diptera: Stratiomyidae) Larvae Affect Their Fatty Acid Composition?

Fatty acids are important compounds for insects, but the requirements for essential fatty acids may differ between insect species. Most of the fatty acids are acquired through the insect’s diet; therefore, supplementing the diet with baker’s yeast (Saccharomyces cerevisiae Meyen ex E.C. Hansen), which produces unsaturated fatty acids, was predicted to affect the fatty acid composition of the insect. The tested insect was the black soldier fly (BSF) (Hermetia illucens L.), that is used as a source of protein and fat in feed. Therefore, there is importance for BSF larvae (BSFL) nutritional composition, especially the unsaturated fatty acids content, which is one of the nutritional limitations for mammalian diets. The dominant fatty acids of the tested BSFL were the saturated fatty acids: lauric, myristic, and palmitic acids, as found in other BSF studies. Oleic acid (c18:1) and linoleic acid (C18:2) were the abundant unsaturated fatty acids in the BSFL. The proportion of linoleic acid was higher in the substrate with the supplemental yeast; however, this did not affect its proportion in the larvae. The higher proportion of linoleic acid may have been exploited as a source for production of saturated lauric acid. Therefore, providing unsaturated fatty acids to the substrate through supplemental baker’s yeast is not the most efficient way to increase the proportion of unsaturated fatty acids in the larvae.

Different Ratios of Corn and Coconut Oil Blends in High‐Fat Diets Influence Fat Deposition without Altering Metabolic Biomarkers in Male Rats

AbstractThe effects of high‐fat diets with the recommended dietary linoleic acid (LA) intake levels on health outcomes have not been studied extensively. This study investigated the effects of high‐fat diets containing different weight ratios of coconut and corn oil with LA levels of &lt;1.00% of energy (very low LA), 2.80% of energy (low LA), 5.80% of energy (moderate LA), and 9.70% of energy (high LA) on fat deposition and selected metabolic biomarkers of male Sprague‐Dawley rats. Their initial and terminal body weights are recorded. Blood, adipose tissue, and liver samples are obtained for analysis after an 8‐week feeding intervention. Compared with the very low‐LA diet, the high‐LA diet resulted in higher body weight gain and epididymal fat deposition. No significant differences are observed in liver‐to‐body weight ratio, blood glucose, visfatin, and leptin levels between the test diets. Serum tumor necrosis factor‐alpha (TNF‐α), insulin, and C‐peptide levels do not significantly increase with the increase in dietary LA levels. High‐LA diet results in higher LA levels in the liver and adipose tissue. It is concluded that a high‐fat diet containing high LA levels induced body weight gain and epididymal fat deposition in rats but has no effect on selected metabolic biomarkers.Practical applications: Linoleic acid (LA) (C18:2) plays an important role as one of the nutritional elements to meet the daily essential fatty acid requirements. However, a full understanding is perplexed by the various ways that LA can be included in the diet when there is a recommendation to substitute saturated fatty acid (SFA), trans‐ or n‐3 fatty acids intake. The data provide additional findings on the effects of excessive dietary intake of LA (C18:2) on fat deposition when different levels of SFAs are replaced.

Effects of dietary essential fatty acid requirements on growth performance, fatty acid composition, biochemical parameters, antioxidant response and lipid related genes expression in juvenile Onychostoma macrolepis

This study was conducted to elucidate effects of dietary essential fatty acid requirements on the growth, physiological characteristics and expressions of some lipid-related genes in juvenile Onychostoma macrolepis. Seven isonitrogenous and isoenergetic purified diets containing tristearin (control group), 2% linoleic acid (LA), 2% α-linolenic acid (LNA), 1% LA + 1% LNA, 1% eicosapentaenoic acid (EPA), 1% docosahexaenoic acid (DHA) and 0.5% EPA + 0.5% DHA were formulated to feed juvenile O.macrolepis (initial body weight:1.51 ± 0.05 g) for eight weeks. The weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of the fish were significantly higher in the LNA group and the EPA + DHA group than in the control group (P < .05). The growth and feed utilization of the fish in the LNA group were similar to those in the EPA + DHA group. The highest levels of 18:2n-6, 18:3n-3, 20:5n-3and 22:6n-3 in muscle and liver were found in the LA group, the LNA group, the EPA group and the DHA group, respectively. The highest concentrations of serum cholesterol (CHOL) and triglyceride (TG) were observed in the fish fed on the LA diet, and there were no significant differences in serum CHOL and TG between the LA group and the LA + LNA group. Serum malondialdehyde (MDA) content was observed to be the highest in the EPA group, DHA group and EPA + DHA group, and significantly higher in the these groups than in the other groups (P < .05). In liver, the superoxide dismutase (SOD) activities and the malondialdehyde (MDA) content were found to be significantly the lowest and the highest in the EPA, DHA and EPA + DHA groups (P < .05). The body fat content of the fish fed on the LA diet was significantly higher than those of the control ones (P < .05). The fatty acid synthetase (FAS), acetyl-CoA carboxylase 1(ACC1) and sterol regulatory element binding protein-1 (SREBP-1) genes involved in the anabolic pathway had the highest expression levels in the LA group. The adipose triglyceride lipase (ATGL), carnitine palmitoyl transferase 1 (CPT1) and peroxisome proliferators-activated receptor α (PPARα) genes involved in the catabolic pathway had the lowest expression levels in the control group. These results showed that the increase in fish body fat content induced by the LA diet was related to the up-regulation of some lipid biosynthesis metabolism genes. This study recommended that the dietary requirement of fatty acids for the optimal growth and health of juvenile O.macrolepis be 2% LNA or 0.5% EPA + 0.5% DHA (approximately 9% dietary fat). Its results might be conducive to optimizing fish diets while designing optimum dietary fatty acid profiles and proportions.

Assessing Polyunsaturated Fatty Acid Essentiality in Florida Pompano

AbstractWe evaluated the growth performance and fatty acid composition of juvenile Florida Pompano Trachinotus carolinus that were fed diets containing different combinations of n‐3 and n‐6 polyunsaturated fatty acids (PUFAs) to assess the relative importance of C18 PUFAs and long‐chain (LC) PUFAs in meeting the essential fatty acid requirements of this species. Juvenile fish (mean ± SD =47.4 ± 0.6 g/fish) were fed diets containing different combinations of n‐3 and n‐6 PUFAs: a positive control containing menhaden fish oil, a negative control containing hydrogenated soybean oil, and experimental diets containing hydrogenated soybean oil amended with ethyl esters of 18:3(n‐3); 18:3(n‐3) and 18:2(n‐6); 22:6(n‐3); 22:6(n‐3) and 20:4(n‐6); or 20:5(n‐3), 22:6(n‐3), and 20:4(n‐6). After 7 weeks, weight gain, feed conversion ratio, and specific growth rate were significantly greater among fish that were fed the positive control feed in comparison with those that received the negative control feed. The addition of n‐3 and/or n‐6 PUFAs to the negative control formulation did not significantly improve performance in any case, although numeric improvements observed for weight gain and feed conversion ratio appeared to suggest some advantage from providing a complement of both n‐3 and n‐6 LC‐PUFAs in the diet. Fatty acid composition varied significantly between all tissues, generally reflecting dietary fatty acid profiles. Tissue fatty acid profiles suggest that Florida Pompano have some ability to elongate and desaturate fatty acids and may be able to survive on diets containing C18 PUFAs, but they perform optimally when provided with LC‐PUFAs directly.

Reevaluating Polyunsaturated Fatty Acid Essentiality in Channel Catfish

AbstractChannel Catfish Ictalurus punctatus reportedly require alpha‐linolenic acid (18:3[n‐3]) for normal growth. However, contradicting studies suggest that elevated dietary levels of this fatty acid might cause growth inhibition, and diets containing linoleic acid (18:2[n‐6]) alone or in combination with 18:0 and 18:1(n‐9) may support growth as well as fish oil (FO)‐based diets containing increased levels of long‐chain (LC) polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (20:5[n‐3]), docosahexaenoic acid (22:6[n‐3]), and arachidonic acid (20:4[n‐6]). Further complicating the understanding of essential fatty acid (EFA) requirements in Channel Catfish are conflicting reports suggesting that feeding LC‐PUFAs can either enhance or suppress growth. We evaluated growth performance and fatty acid composition of juvenile Channel Catfish that were fed seven diets containing n‐3 and n‐6 C18 PUFAs and/or LC‐PUFAs in different combinations: a positive control containing menhaden FO, a negative control containing hydrogenated soybean oil, and experimental diets containing hydrogenated soybean oil amended with ethyl esters of 18:3(n‐3); 18:3(n‐3) and 18:2(n‐6); 22:6(n‐3); 22:6(n‐3) and 20:4(n‐6); or 20:5(n‐3), 22:6(n‐3), and 20:4(n‐6). After 18 weeks, we observed no differences in growth or conversion efficiency. However, fish that were fed diets supplemented with C18 PUFAs and LC‐PUFAs numerically outperformed those fed the FO‐based positive control feed. Tissue fatty acid profiles generally mirrored that of the diet provided, except that saturates were underrepresented in the tissues. Channel Catfish that received the EFA‐free negative control feed or the diets supplemented with 18:3(n‐3) and 18:2(n‐6) or 20:4(n‐6) and 22:6(n‐3) developed elevated ratios of 22:5(n‐6) : 22:6(n‐3), whereas an elevated ratio of 20:3(n‐9) : 20:4(n‐6) was observed among fish that were fed the 22:6(n‐3) supplemented diet. Our findings suggest that C18 PUFA and LC‐PUFA diets appear to equally satisfy the EFA requirements of this species; however, intact dietary LC‐PUFAs should be carefully balanced to avoid antagonistic effects of surplus n‐3 LC‐PUFA on n‐6 LC‐PUFA biosynthesis.