Dietary Lipid Content Research Articles

Interaction between dietary lipid and bile acids on the growth performance and lipid metabolism in abalone Haliotis discus hannai Ino

A 105-day feeding trail was conducted to evaluate the effects of dietary lipid and bile acids levels as well as their interactions on the growth, digestion and lipid metabolism in abalone Haliotis discus hannai (initial weight: 5.29 ± 0.02 g). Eight isonitrogenous diets with two levels of lipid (4.3% and 6.3%) and four levels of bile acids (0, 15, 60 and 240 mg/kg) were formulated in a 2 × 4 two-factor design. The results showed that 6.3% of dietary lipid decreased the weight gain rate (WGR) of abalone, which increased as the dietary bile acids level increasing from 0 mg/kg to 60 mg/kg. The treatment with the highest WGR contained 4.3% of dietary lipid and 60 mg/kg of dietary bile acids. In the groups with 4.3% of dietary lipid, the expression of genes involved in lipid transport and lipolysis was increased (P < 0.05). And dietary bile acids increased the expression of genes involved in lipid transport and lipolysis while decreased the expression of genes involved in lipogenesis (P < 0.05). The expression of genes involved in lipid metabolism, such as cluster of differentiation, fatty acid transport protein, microsomal triglyceride transfer protein and peroxisome proliferator-activated receptor α, revealed the interactions between dietary lipid and bile acids (P < 0.05). In conclusion, the growth and digestion of abalone were negatively impacted by an excessively high dietary lipid content (6.3%). Appropriate supplemented level of dietary bile acids (60 mg/kg) significantly enhanced the growth and digestion of abalone. Dietary lipid and bile acids had an interactive effect on the lipid metabolism in abalone, including lipid transport, lipolysis and lipogenesis.

Accelerated abdominal lipid depletion from pesticide treatment alters honey bee pollen foraging strategy, but not onset, in worker honey bees.

Honey bee abdominal lipids decline with age, a change thought to be associated with the onset of foraging behavior. Stressors, such as pesticides, may accelerate this decline by mobilizing internal lipid to facilitate the stress response. Whether bees with stressor-induced accelerated lipid loss vary from controls in both the onset of foraging and nutritional quality of collected pollen is not fully understood. We asked whether stressors affect foraging behavior through the depletion of abdominal lipid, and whether stress-induced lipid depletion causes bees to forage earlier and for fattier pollen. We tested this by treating newly emerged bees with one of two pesticides, pyriproxyfen (a juvenile hormone analog) and spirodiclofen (a fatty acid synthesis disruptor), that may affect energy homeostasis in non-target insects. Bees fed these pesticides were returned to hives to observe the onset of foraging behavior. We also sampled foraging bees to assay both abdominal lipids and dietary lipid content of their corbicular pollen. Initially, spirodiclofen-treated bees had significantly more abdominal lipids, but these declined faster compared with controls. These bees also collected less, yet more lipid-rich, pollen. Our results suggest that bees with accelerated lipid decline rely on dietary lipid content and must collect fattier pollen to compensate. Pyriproxyfen treatment reduced the age at first forage but did not affect abdominal or collected pollen lipid levels, suggesting that accelerated fat body depletion is not a prerequisite for precocious foraging.

Regulation of lipid metabolism by gut microbiota in aquatic animals

AbstractLipids are an essential component of living beings and an important group of nutrients. As the gut microbiota plays important roles in the intestinal absorption and extraintestinal metabolism of dietary lipids, the current review addresses the recent progress regarding the interactions between the gut microbiota and lipid metabolism in aquatic animals, with a focus on fish. We discuss in detail how dietary lipid sources and content affect the composition of the gut microbiome and the mechanism by which the gut microbiota affects the lipid metabolism of the host. This interaction is largely mediated via microbial lipases, short‐chain fatty acids and the gut‐liver axis. The latter refers to the metabolism of biliary salts and acids, the regulation of their synthesis by gut microbes and their impact on the lipid metabolism. Finally, we briefly discuss how probiotic supplementation modulates the host's microbiome, and how probiotics have a beneficial effect on health and welfare of farmed aquatic animals. Although the influence of intestinal microbiota on lipid metabolism has been explored before, further research is needed to profoundly investigate the molecular mechanisms by which microbial metabolites (SCFAs and bile acids) induce lipid metabolism.

Molecular Characterization and Expression Response of Ghrelin, GLP-1 and PYY to Fasting, Dietary Lipid, and Fatty Acids in Silver Pomfret (Pampus argenteus)

Ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) are potent hormones mediating food intake according to the nutritional status in fish. However, limited information is available on these genes and their expression in response to nutrition in silver pomfret (Pampus argenteus). A comparison analysis revealed that ghrelin and GLP-1 were relatively conserved in marine fish. PYYa and PYYb shared a low identity and were clustered to different PYY branches. Ghrelin, pyya, and pyyb mRNAs were highly expressed in the brain, while glp-1 was highly expressed in the gills and liver. The ghrelin mRNA expression was relatively high an hour post-feeding and decreased after 3 to 72 h of fasting. The glp-1 mRNA expression was increased after 6 to 24 h of fasting. The pyya mRNA expression was increased after 72 h of fasting, while the pyyb expression remained stable during fasting. The diet with 14% lipid promoted the expressions of glp-1, pyya, and pyyb, but inhibited the ghrelin expression. The ghrelin expression in the intestine was increased after palmitic acid, oleic acid (OA), linoleic acid (LA), α-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) incubation. OA decreased the expression of glp-1 and increased the expression of pyya. The expression of pyyb was downregulated by LA, DHA, and EPA. These results suggest the importance of ghrelin, glp-1, and pyy in coordinating food intake in response to fasting, dietary lipid concentration, and fatty acids in silver pomfret.

Effects of a High-Fat Diet on Intestinal and Gonadal Metabolism in Female and Male Sea Cucumber Apostichopus japonicus.

Parental nutrient reserves are directly related to reproductive performance in sea cucumbers. This study focused on the lipid requirements of male and female sea cucumbers Apostichopus japonicus during the reproductive stage and analyzed their physiological responses to a high-fat diet (HFD). The intestinal lipid metabolites and microbiome profile changed significantly in animals fed with the HFD, as given by an upregulation of metabolites related to lipid metabolism and an increase in the predominance of Proteobacteria in the microbiome, respectively. The metabolic responses of male and female sea cucumbers to the HFD differed, which in turn could have triggered sex-related differences in the intestinal microbiome. These results suggest that the lipid content in diets can be differentially adjusted for male and female sea cucumbers to improve nutrition and promote reproduction. This data contributes to a better understanding of the reproductive biology and sex differences of sea cucumbers.

Production of Cookies Enriched with Bioactive Compounds through the Partial Replacement of Wheat Flour by Cocoa Bean Shells.

Approximately 500 thousand tons of cocoa bean shells (CSs) are generated annually and treated as waste. However, their composition is of great nutritional, technological, and economic interest due to their dietary fiber (46.4 to 60.6%), protein (11.6 to 18.1%), and lipid contents (2 to 18.5%), as well as the presence of flavonoids and alkaloids. Thus, this study aimed to obtain CS flour by milling the CSs, characterizing the flour according to its chemical composition and functionalities, and then applying it in the production of cookies, substituting a wheat flour portion (10, 20, 30, and 40%) with CS flour. Cookies were characterized in terms of water, lipids, proteins, phenolic (PC), and total flavanol (FLA) contents, and specific volume (SV), hardness (H), and L*, a*, and b color scale parameters. Increasing the amount of CS showed positive results, as the cookies were enriched with PC (0.68 to 2.37 mg gallic acid equivalents/g of sample) and FLA (0.10 to 0.19 mg epicatechin equivalents/g of sample) but increased hardness (353 to 472 N). By associating the responses, it was concluded that the wheat flour replacement with 30% CS presented values of PC and FLA 3 and 1.6 times higher than the control and could be a formulation of interest to consumers.

Effects of Varying Quantities of Dietary Protein and Lipid on Growth Performance, Blood Biochemical Parameters, Digestive Histology and Enzyme Activity in Juvenile Gold Fish (Carassius auratus)

Background: Goldfishes are used as an ideal model for nutritional studies in larval and juvenile cyprinids. However, of the limited published data that is available on goldfish, protein requirements have varied from 29% to 53% for goldfish larvae. So the present study was undertaken to determine growth performance of goldfish, C. auratus fed with different dietary protein and lipid levels to develop nutritionally balanced diets. Methods: In this study, Carassius auratus juveniles were fed with six diets containing two protein levels (300 and 400 g/kg) and three lipid levels (40, 80 and 120 g/kg) to evaluate the optimal dietary protein and lipid levels to determine growth performance, blood biochemical parameters, digestive enzyme activity and intestinal and liver histology. Result: According to the findings, gold fish juveniles when fed a casein-dextrin based semi-purified diet containing 400 g/kg dietary protein and 80 g/kg dietary lipid content, maximum development and feed utilisation are seen. Second-order polynomial regression also suggests that a diet with 400 g/kg protein and 80 g/kg lipid is best for juvenile goldfish growth and feed utilisation.

Effects of palm olein and palm stearin on cecal and fecal microbiota of C57BL/6J mice under low and high fat intakes

This work aimed to study the effects of dietary lipid composition and content on cecal and fecal microbiota of mice fed the following diets for 8 weeks: palm olein (PO)-based low-fat diet, PO-based high-fat diet, palm stearin (PS)-based low-fat diet, and PS-based high-fat diet. Increasing the dietary PS level favored the growth of Firmicutes over Bacteroidetes in the cecum and feces. In addition, it significantly elevated the total lipid (p < 0.01) and bile acid content (p < 0.01) in feces, resulting in the enrichment of fat-degrading and bile-acid tolerant genera within the families Ruminococcaceae and Lachnospiraceae. Although increasing the PO intake also caused obesity in mice, it did not affect the microbial structure. When fat intake is constant, only at a high-fat level can PS (vs PO) induce the above-mentioned microbial shifts. These results highlighted the combined roles of lipid quality and quantity on the gut microbiota.

41. Effects of breed, growth rate and dietary lipid concentration on lipophilic contaminant accumulation into growing cattle: insight from a physiologically-based toxicokinetic model

41. Effects of breed, growth rate and dietary lipid concentration on lipophilic contaminant accumulation into growing cattle: insight from a physiologically-based toxicokinetic model

Effects of dietary protein and lipid levels on growth, feed utilization and meat quality of clown knifefish (Chitala chitala)

Effects of dietary protein and lipid levels on growth, feed utilization and fillet quality of clown knifefish (Chitala chitala) were implemented to determine the protein and energy requirements of this species at 400 g stage. A 4 x 3 factorial design with four dietary protein levels (25%, 30%, 35% and 40%) and three dietary lipid levels (6, 9, and 12%) corresponded to 3 energies levels 18, 19 and 20 MJ/kg. Clown knifefish (407 ± 5.0 g) was stocked at a density of 10 fish/m2. The experiment was arranged in a completely randomized design in triplicate tanks for 8 weeks. There was a significant interaction effect (P&lt;0.05) between protein and lipid levels on weight gain and specific growth rate with the fish growth being highest in the 35 CP-9% lipid treatment. The survival rate of fish was not affected (P&gt;0.05) by dietary protein and lipid levels and ranged from 93.3 to 100%. The feed efficiency of fish was influenced by dietary protein or lipid content as well as the interaction between these two factors. Protein utilization efficiency increased as protein content increased, and diet contained t 35% protein and 9% lipid, enhanced chewiness and hardness of fish paste. These results showed that clown knifefish fed 32.8% dietary protein and 19 MJ energy with a P/E ratio of 18.6 had the optimal growth and the best quality of fish meat.

Optimization of dietary protein and lipid levels for butter catfish, (Ompok bimaculatus) (Bloch, 1794) fingerlings: An appraisal on growth, body composition, digestive enzymes, and metabolic function

ABSTRACT A completely randomized 3 × 3 factorial feeding trial was conducted to evaluate the effects of dietary protein and lipid levels on growth, feed utilization, body composition, and digestive as well as metabolic enzymes of the butter catfish (Ompok bimaculatus) fingerlings. Fish (average weight 0.66 ± 0.12 g; 30 d) were fed nine experimental diets containing three protein levels (35%, 40%, 45%) and three lipid levels (5%, 10%, 15%) in triplicate groups for a period of 90 days. The formulated diets were named P35L05, P35L10, P35L15, P40L05, P40L10, P40L15, P45L05, P45L10, and P45L15 (P = Protein; L = Lipid) respectively. The results indicated no protein-sparing effect of lipid in O. bimaculatus fingerlings beyond 35% dietary protein. Overall, diets P40L5 and P35L10 had significantly (P < 0.05) higher SGR (% day−1) and lower FCR than other experimental groups. The highest weight gain (10.89 ± 0.07 g) and carcass protein (16.71 ± 0.2%) were recorded in fish fed diet P40L05. Increasing dietary lipid levels brought about an increase in carcass lipid in fish. Activities of α-amylase and acid-protease were decreased (except at 5% lipid), whereas alkaline-protease was increased with increasing dietary protein. An increase in pyruvate kinase (PK, glycolytic enzyme) activity and decrease in glucose-6-phosphate dehydrogenase (G6PD, lipogenic enzyme) activity were noticed with increasing dietary lipid content. A decrease in PK and increase in G6PD activities were observed with increasing dietary protein levels. Activities of the gluconeogenic enzymes (glucose-6-phosphatase, fructose-1,6-phosphatase) increased significantly (P < 0.05) with increasing dietary protein and lipid levels. Amino acid catabolizing enzymes, alanine transaminase and aspartate transaminase, were slightly increased with increasing dietary protein levels. Considering growth, body composition, metabolic function, and survivability (>95%), the diet containing 40% crude protein with 5% lipid might be suggested as optimum for O. bimaculatus fingerlings under the tested conditions.

Early Mild Stress along with Lipid Improves the Stress Responsiveness of Oscar (Astronotus ocellatus).

Early-life exposure to mild stressors can assist animals in coping with more stressful events in later life. This study was aimed at investigating how early stress and dietary lipid contents affect growth, hematology, blood biochemistry, immunological responses, antioxidant system, liver enzymes, and stress responses of oscar (Astronotus ocellatus) (6.8 ± 0.7 g). Six experimental treatments were HL0Stress (high-lipid diet and without stress), HL2Stresses (high-lipid diet and two-week stress), HL4Stresses (high-lipid diet and four-week stress), LL0Stress (low-lipid diet and without stress), LL2Stresses (low-lipid diet and two-week stress), and LL4Stresses (low-lipid diet and four-week stress). During the ten-week trial, fish fed high-lipid diets grew faster (46.41 ± 4.67 vs. 38.81 ± 2.81) and had a lower feed conversion ratio (2.21 vs. 2.60) than those fed low-lipid diets (P < 0.05). After acute confinement stress (AC stress), high-lipid groups had higher survival than low-lipid treatments (81.25% vs 72.92%) (P < 0.05). Fish subjected to two-time stress (2Stresses) had a higher survival rate after AC stress (90.63% vs. 62.50%), hematocrit, white blood cell, blood performance, total protein, high-density lipoproteins, cholesterol, triglyceride, alternative complement activity (ACH50), superoxide dismutase, glutathione peroxidase, and alkaline phosphatase levels than those not stressed (P < 0.05). Contrariwise, glucose, cortisol, alanine aminotransferase, and aspartate aminotransferase levels were significantly lower in the 2Stresses groups compared with 0Stress fish (P < 0.05). Collectively, these findings suggest stressing the signs of adaptation in 2Stresses fish. However, a higher number of early stress events (4Stresses) appears to exceed the threshold of manageable stress levels for this species. In conclusion, the HL2Stresses group outperformed the other treatments in terms of growth, health status, and stress responsiveness. Although fish welfare must be considered, these results suggest that early mild stress can result in a greater survival rate after fish are exposed to later acute stress.

Response of lipid-related composition of farmed tiger puffer (Takifugu rubripes) to starvation under different dietary lipid levels in the previous feeding period

Starvation is a natural process in the life cycle of wild fish, and also a means of body composition regulation for farmed fish. This study with tiger puffer was aimed at investigating the effects of starvation on lipid and fatty acid compositions in fish with different levels of lipid accumulation. Different lipid accumulation levels in tiger puffer were obtained by manipulating the dietary lipid content (8%, 12%, and 16%) in a previous feeding period for 9 weeks. Each diet was fed to sextuplicate net cages in this feeding trial. At the end of the feeding trial, fish with an average initial body weight of 68.26 g were then subjected to starvation for 31 days. Tissue samples were collected at the end of the feeding trial and at 1, 4, 9, 16, and 31 days after starvation. The results showed that the muscle lipid content decreased linearly with starvation time, but the liver lipid content increased firstly (1–16 days of starvation), and thereafter sharply declined. However, no interaction between starvation time and dietary lipid level was observed in the effects on liver and muscle lipid composition. Starvation had slight effects on muscle and liver fatty acid compositions, except that it largely increased the C22:5n-3 content in the muscle. Starvation primarily mobilized C14:0, C16:1n-7, C20:1n-9 and C22:1n-9 in the muscle, and C18:0, C18:1n-9, and EPA in the liver. Interactive effects between starvation time and dietary lipid level were observed for many fatty acids. Short-term (1–4 days) starvation increased the muscle texture parameters, but longer-term starvation decreased them. In conclusion, starvation exerts significant effects on lipid and fatty acid composition in farmed tiger puffer. Customed lipid and fatty acid composition, and possibly customed fillet quality could be obtained through manipulation of starvation time and dietary lipid level in the previous feeding period.

Effect of diets containing full-fat Hermetia illucens on rainbow trout microbiota: A dual cultivation-independent approach with DGGE and NGS

Given the drift to improve economic and ecological sustainability of the aquaculture sector, novel ingredients fulfilling these requirements are sought. Hermetia illucens, commonly called black soldier fly, (Diptera: Stratiomydae; H) is a promising dietary protein source but its effect on fish gut microbiota is still to be clarified. The aim of the present study was to increase the knowledge of the effect of dietary full-fat H meal on rainbow trout (Oncorhynchus mykiss) microbiota and, in particular, on intestinal mucosa-adherent microbiota by applying a dual approach based on polymerase chain reaction-denaturing gradient gel electrophoresis and high-throughput sequencing of the 16S rRNA gene. Rainbow trout (initial body weight of 137.3 ± 10.5 g) was fed for 98 days with a control diet (H0) containing fishmeal and protein-rich vegetable ingredients and an experimental diet (H50) where 50% of the fishmeal had been replaced by full-fat H meal rich in saturated fatty acids.Proteobacteria, Firmicutes and Actinobacteria were generally present in all samples, although the core microbiota (relative prevalence higher than or equal to 80% in all samples) only consisted of the proteobacteria Caulobacter, Delftia, Agrobacterium and Ochrobactrum. In addition, Streptococcus infantis and a member of the Cytophagaceae family were part of the core taxa of mucosa samples. Tenericutes were abundant in pyloric caeca samples and, among them, Mycoplasmataceae seemed to increase in the group fed the high saturated fatty acid diet containing H meal; a consideration about the connection between this bacterial group and the dietary lipid content must be considered. Dietary treatment did not clearly affect alpha-diversity metrics, but mucosa samples tended to be more resilient to dietary changes than content samples. Permutational analysis of variance showed significantly different β-diversities between diets (p < 0.05) but principal coordinates analysis did not confirm this result.Diets for rainbow trout containing full-fat H meal determined interesting modifications in the gut microbiota with patterns similar to the ones found in the literature. The dietary lipids can exert an effect on microbiota. Nonetheless, research data on this topic are still scarce and further studies are highly encouraged.

Development of muffin with the incorporation of olive pomace flour, extra virgin olive oil and hydrolyzed soy protein

Olive pomace flour, extra virgin olive oil and hydrolyzed soy protein are ingredients rich in compounds with beneficial health properties, such as phenolic compounds, dietary fiber, amino acids and fatty acids. In this sense, the present study aimed to evaluate the influence of partial replacement of wheat flour, hydrogenated vegetable fat and sucrose by olive pomace flour, extra virgin olive oil and hydrolyzed soy protein, respectively, in muffin-type cakes. The determination of the ideal formulation with the alternative ingredients was carried out through the Response Surface Methodology, exploring a Simplex-Centroid Mixture Design using physicochemical parameters as dependent variables. The optimum point was obtained using 38.00 % olive pomace flour, 3.75 % extra virgin olive oil, and 4.05 % hydrolyzed soy protein. In general, it was observed that the alternative ingredients had positive effects on the texture profile of the muffins and provided products with darker shades, characteristics of the ingredients used. Nutritionally, an increase in total dietary fiber, ash and lipid content was observed. In contrast, the starch content decreased, but the total caloric value was similar between the standard sample and the optimum. Therefore, the partial replacement of ingredients demonstrated feasibility and potential for bakery goods.

Dietary fatty acid composition affects the apparent digestibility of algal carotenoids in diets for Atlantic salmon, Salmo salar

Astaxanthin (Axn) is the most commonly used carotenoid to enhance the flesh colouration of salmonids, which is one of the key criteria perceived to reflect the freshness and nutritional quality of the product and consequently affecting its price. However, the digestibility of astaxanthin by salmonids is highly variable, ranging between 20% and 60%. Axn digestibility can also be affected by total dietary lipid content and fatty acid (FA) composition (saturated FAs [SFA], mono-unsaturated FAs [MUFA] or poly-unsaturated FAs [PUFA]). This experiment contained four diets fed to juvenile Atlantic salmon for 2 weeks. Two diets formulated with either synthetic or algal carotenoids combined with poultry oil and two additional diets containing algal carotenoids with either tallow or canola oil. The aim of this study was to compare the feed intake, as a measure of diet palatability, and apparent digestibility (AD) of Axn between the two diets containing either synthetic or algal carotenoids. Results showed that algal carotenoids had significantly higher AD than synthetic Axn and that high levels of SFA, such as those in tallow, may inhibit the AD of algal carotenoids. Meanwhile, the high levels of MUFA and, in particular 18:1n-9, in canola oil significantly improved the AD of algal carotenoids for Atlantic salmon. This study demonstrates the utility of algal carotenoids as natural pigment alternatives for farmed salmon, particularly beneficial when combined with different oil sources that contain more 18:1n-9, such as in canola, and less SFA, such as in tallow, in order to optimize the utilization of dietary carotenoids.

Lipidomic Profiling Reveals the Reducing Lipid Accumulation Effect of Dietary Taurine in Groupers (Epinephelus coioides).

A lipidomic analysis was conducted to provide the first detailed overview of lipid molecule profiles in response to dietary lipid and taurine and associations of liver lipid-lowering effects of dietary taurine with lipid molecular species and the positional distributions of fatty acids in the liver of juvenile orange-spotted groupers (Epinephelus coioides). The results indicated that the liver was more sensitive to varied dietary lipid and taurine contents than the muscle with regard to lipid molecules. A total of 131 differential lipid molecules (DLMs) were observed in the liver of groupers when dietary taurine was increased from 0 to 1% at 15% lipid, among which all the up and down-regulated DLMs are phospholipids (PLs) and triglycerides (TGs), respectively. The liver content of TGs containing 18:2n-6 attached at the sn-2 and sn-3 positions on the glycerol backbone increased with increasing dietary lipid from 10 to 15% but decreased with increasing dietary taurine from 0 to 1%. Therefore, dietary taurine can not only reduce lipid accumulation through decreasing the contents of TGs containing 18:2n-6 at the sn-2 and sn-3 positions but also enhance the anti-inflammatory capacity and health status of groupers. This study will also provide a new insight into the function of taurine in farmed fish.

GROWTH OF JUVENILES OF THE FAT SNOOK, Centropomus parallelus, IN RESPONSE TO DIETARY LIPID, ENERGY AND PROTEIN

This study evaluated the growth of fat snook Centropomus parallelus in response to the dietary total lipids, gross energy (GE) and crude protein (CP) content. In the 1st experiment, five isonitrogenous diets with 541.7 ± 2.4 g kg-1 CP varied their lipid content in 113, 151, 160, 189 and 200 g kg-1 and GE in 18.8, 19.4, 20.4, 21.2 and 22.2 MJ kg-1, respectively. A total of 300 fish with 6.5 ± 2.4 g were stocked in 30 tanks of 1 m3 under 10 fish m-³ and reared for 96 days. There were no differences in fish final body weight (38.2 ± 12.5 g), daily weight gain (DWG, 0.35 ± 0.04 g day-1) and specific growth rate (SGR, 1.92 ± 0.11 day-1) among dietary treatments. Feed conversion ratio (FCR) was 1.76 ± 0.17 with a protein efficiency ratio of 1.06 ± 0.10. The viscerosomatic (VSI) and visceral fat indices (VFI) raised significantly with an increase in the dietary lipid while the hepatosomatic index (HSI) was unaffected. There was a significant reduction in feed intake as the dietary lipid content reached 189 g kg-1. In a 2nd study, five isolipidic diets (114.4 ± 1.9 g kg-1 lipids) with decreasing levels of CP and GE of 578, 535, 505, 465, and 430 g kg-1 and 20.5, 19.9, 19.4, 18.9, and 18.1 MJ kg-1, respectively, were evaluated. A total of 1,450 fish of 5.8 ± 2.1 g were reared in 30 tanks of 5.8 m³ under 10 fish m-3 for 93 days. Final survival reached 93.5 ± 5.5%. Fish DWG (0.27 ± 0.05 g day-1) and SGR (1.78 ± 0.11 % day-1) did not vary in response to dietary CP. Final body weight significantly reduced while HSI increased in fish fed the 430 g kg-1CP diet compared with fish fed the 578 g kg-1 CP diet. Results of this work indicated that fish between 5.8 g and 40.8 g wet body weight can maximize growth when fed diets containing 113.2 g kg-1 lipids, 540.5 g kg-1 CP and a 34.7 MJ kg-1 energy to protein ratio.&#x0D; Keywords: Centropomus parallelus, fat snook, protein, lipid, energy.

Effects of Dietary Protein and Lipid Levels on Growth, Body Composition, Blood Biochemistry, Antioxidant Capacity and Ammonia Excretion of European Grayling (Thymallus thymallus)

This study evaluated growth, body composition, antioxidant capacity, innate immunity and ammonia excretion of European grayling (Thymallus thymallus) fed diets containing different protein and lipid contents. Six diets were produced to contain 30, 40, or 50% protein and 10 or 20% lipid. Juvenile fish averaging 25.2 ± 0.28 g were stocked into eighteen 450-L circular tanks in a recirculating aquaculture system (RAS) and fed the test diets to satiation twice daily for 12 weeks. Fish weight gain (WG) was enhanced (P &amp;lt; 0.05) as dietary protein increased from 30% (229% WG) to 40% (262% WG) and plateaued thereafter. Enhancing protein and lipid content of diet led to reduced feed intake. Also, feed efficiency was improved by increasing dietary protein (by 40.8%) and lipid (by 16.5%) levels. An interaction of protein and lipid was found on whole-body lipid, and muscle lipid content increased as dietary lipid level increased. Muscle arachidonic acid (ARA), eicosapentaenoic acid (EPA, 20:5n-3) and total n-6 long-chain polyunsaturated fatty acids (LC-PUFA) contents enhanced by increasing dietary protein level. Moreover, increasing fat content of diet led to enhanced muscle linoleic acid, linolenic acid, total monounsaturated fatty acids (MUFA), total n-6, ratio of docosahexaenoic acid (DHA, 22:6n-3) to EPA and n-6/n-3. However, EPA, DHA, total n-6 LC-PUFA, total n-3, total n-3 LC-PUFA, and EPA/ARA ratio decreased at higher dietary lipid level. Serum triglyceride (TG) level and lactate dehydrogenase (LDH) activity decreased as dietary protein level increased. Increasing fat content of diet led to enhanced serum TG, cholesterol and glucose concentrations and reduced alanine aminotransferase, aspartate amino transferase and LDH activities. Serum malondialdehyde concentration was enhanced by increasing both dietary protein and lipid. Furthermore, serum myeloperoxidase activity was enhanced at higher dietary lipid level. Water ammonium nitrogen (NH4+-N) concentration was measured after 5 and 24 h of last feeding, and the results indicated the reduction of ammonia excretion as dietary lipid content increased. These findings suggest that 40% dietary protein can support optimal growth of juvenile European grayling reared in RAS and increasing lipid content from 10 to 20% can improve feed utilization and reduce ammonia excretion to the rearing water.

Dietary protein and lipid concentrations affect the growth, nutritional indices, and whole-body composition of long-whisker catfish, Mystus gulio, fry

Dietary protein and lipid concentrations affect the growth, nutritional indices, and whole-body composition of long-whisker catfish, Mystus gulio, fry