Interactive effects of dietary lipid and phenotypic feed efficiency on the expression of nuclear and mitochondrial genes involved in the mitochondrial electron transport chain in rainbow trout.

A 2 × 3 factorial study was conducted to evaluate the effects of dietary lipid level on the expression of mitochondrial and nuclear genes involved in electron transport chain in all-female rainbow trout Oncorhynchus mykiss. Three practical diets with a fixed crude protein content of 40%, formulated to contain 10% (40/10), 20% (40/20) and 30% (40/30) dietary lipid, were fed to apparent satiety to triplicate groups of either low-feed efficient (F120; 217.66 ± 2.24 g initial average mass) or high-feed efficient (F136; 205.47 ± 1.27 g) full-sib families of fish, twice per day, for 90 days. At the end of the experiment, the results showed that there is an interactive effect of the dietary lipid levels and the phenotypic feed efficiency (growth rate and feed efficiency) on the expression of the mitochondrial genes nd1 (NADH dehydrogenase subunit 1), cytb (Cytochrome b), cox1 (Cytochrome c oxidase subunits 1), cox2 (Cytochrome c oxidase subunits 2) and atp6 (ATP synthase subunit 6) and nuclear genes ucp2α (uncoupling proteins 2 alpha), ucp2ß (uncoupling proteins 2 beta), pparα (peroxisome proliferator-activated receptor alpha), pparß (peroxisome proliferatoractivated receptor beta) and ppargc1α (proliferator-activated receptor gamma coactivator 1 alpha) in fish liver, intestine and muscle, except on ppargc1α in the muscle which was affected by the diet and the family separately. Also, the results revealed that the expression of mitochondrial genes is associated with that of nuclear genes involved in electron transport chain in fish liver, intestine and muscle. Furthermore, this work showed that the expression of mitochondrial genes parallels with the expression of genes encoding uncoupling proteins (UCP) in the liver and the intestine of rainbow trout. This study for the first time presents the molecular basis of the effects of dietary lipid level on mitochondrial and nuclear genes involved in mitochondrial electron transport chain in fish.

Corrigendum to "Revaluating the dietary methionine requirements in an improved strain of Nile tilapia (Oreochromis niloticus)" [Heliyon 9 (3), (March 2023) Article e14376].

[This corrects the article DOI: 10.1016/j.heliyon.2023.e14376.].

Comparative estimation of the lysine requirements in two generations of improved strain of Nile tilapia (Oreochromis niloticus) at the grow-out stage.

A 3 × 2 factorial experiment was conducted to investigate the effects of dietary lysine on growth performance, body indices, feed intake, feed efficiency, whole body nutrient composition and amino acid deposition in two successive generations (16th and 17th) of GIFT (Oreochromis niloticus). Three diets containing different levels of lysine at 1.16%, 1.56% and 2.41% were prepared for the feeding trial. Triplicate groups of fish with an initial body weight of 155 g were fed to apparent satiation for 10 weeks in a recirculating aquaculture system. Apparent digestibility coefficients (ADC) of dry matter, crude protein, crude lipids, and total carbohydrates were measured in the experimental diets. At the end of the experiment, no interactions between dietary lysine levels in diet and fish generation were observed on all parameters except for the condition factor (CF) and ADC of crude protein. However, dietary lysine level significantly affected the final weight, weight gain, thermal unit growth coefficient (TGC), protein efficiency ratio (PER) and ADC of dry matter regardless of the fish generation. Final weight, weight gain and TGC of fish were the highest in fish fed 2.41% dietary lysine in diet or 6.52% lysine in the protein. PER was the lowest in fish fed 1.16% dietary lysine. The final weight and the body's accumulation of isoleucine, phenylalanine, and alanine were significantly affected by the fish generation, with the 17th generation having the best performance. Increase growth and higher lysine requirement observed in the improved generation (17th) compared to the (16th) generation at grow out phase indicating that genetic improvement may have changed the dietary lysine requirement.

Revaluating the dietary methionine requirements in an improved strain of nile tilapia (Oreochromis niloticus).

It has been shown with terrestrial animals that the genetic improvement increases the nutrient requirements of the animal, which becomes more efficient in using these nutrients to achieve their higher growth potential. This study was conducted to estimate the dietary methionine requirements of different generations of the Genetically Improved Farmed Tilapia (GIFT) strain of Nile tilapia at the juvenile stage (17.51 g-19.55 g initial body weight). To achieve this objective, a completely randomized 2 × 6 factorial design was applied, with the genetic background of fish (generation) as the first independent variable with two levels, the 16th and 17th generations, and the methionine content of the diet as the second independent variable, with 6 graded levels, 0.52, 0.62, 0.84, 0.94, 1.04 and 1.27% of methionine in the diets, respectively. At the end of the 42-day experiment, the interaction effect of the generation × diet was not significant (P > 0.05) for any of the response parameters studied. The genetic improvement led to 15% more growth in the 17th generation than the 16th generation of the GIFT strain of Nile tilapia, which was accompanied with better feed conversion ratio, protein productive value, and energy productive value in the former generation (P < 0.05). Whatever the generation considered, the optimum dietary methionine requirement for the growth of the improved GIFT strain of Nile tilapia was estimated in this study, using the broken-line model, between 0.75% and 0.80% of the diet (with a cysteine level of 0.50% of the diet), which is higher than 0.49% of the diet previously estimated for conventional Nile tilapia at the juvenile stage. Therefore, the genetic improvement applied to the GIFT strain of Nile tilapia likely led to a higher methionine and total sulfur amino acid requirement than the conventional strains. The results of this study support the need to update the existing nutrient requirement databases of fish, in order to ensure that diets are formulated to effectively satisfy the requirements of not only conventional, but also improved strains of fish, for the full expression of their accrued growth potential of the latter strains.

Influences of dietary biotin and avidin on growth, survival, deficiency syndrome and hepatic gene expression of juvenile Nile tilapia Oreochromis niloticus.

This study was undertaken to assess the interactive effects of dietary biotin and avidin on growth, feed conversion, survival and deficiency syndrome of tilapia and to determine the influence of dietary biotin deficiency on the expression of key genes related to biotin metabolism in tilapia. Six iso-nitrogenous and iso-energetic diets based on a common purified basal diet (vitamin-free casein as the protein source) were prepared for this study. The six dietary groups were 0 g avidin with 0 mg biotin (A0B0), 0 g avidin with 0.06 mg biotin/kg diet (A0B1), four avidin-supplemented diets incorporating at a incremental concentrations 0.25, 0.5, 1.0 and 2.0 g/kg diet with 0.06 mg biotin/kg diet (A15B1, A30B1, A60B1 and A120B1). Fish were hand-fed three times a day to apparent satiation for 12 weeks. Each diet was fed to three replicate groups of fish. Fish were kept in glass aquaria in a recirculating aquaculture system under standardized environmental conditions. Growth was significantly higher in fish that received the biotin-supplemented diet (A0B1), compared to diets lacking biotin or supplemented with avidin. Tilapia fed higher concentration of avidin-supplemented diets (A60B1 and A120B1) showed significant growth depression and displayed severe deficiency syndromes such as lethargy, anorexia, circular swimming and convulsions, which ultimately lead to death. There was a strong proportional linear relationship between the avidin content of the diet and feed conversion ratio, FCR (y = 0.43x + 0.135; r = 0.960; P < 0.001) and strong inverse relationship with protein efficiency ratio, PER (y = -0.309x + 2.195; r = 0.961; P < 0.0001). Elevated levels of biotinidase, pyruvate carboxylase, propionyl-CoA carboxylase-A and propionyl-CoA carboxylase-B transcripts were noted in fish fed all graded level of avidin-supplemented diets. A broken-line analysis indicated that feeding tilapia a diet with 44.5 times more avidin than the dietary biotin requirement can induce deficiency syndromes including retarded growth, when analyzing the data of percentage weight gain.

Combined effects of diets and temperature on mitochondrial function, growth and nutrient efficiency in rainbow trout (Oncorhynchus mykiss).

A 4×3 factorial experiment was conducted to evaluate the effects of two dietary protein sources (mixed fishmeal/plant protein-, and plant protein- based diet), two dietary lipid levels (10% and 20%) and three water temperatures (10°C, 14°C, and 18°C) on the growth performance, nutrient utilization efficiencies and mitochondrial enzyme complex activities in rainbow trout Oncorhynchus mykiss (average weight±SD, 39.5±5g) over a 180day rearing period. At the end of the experiment, weight gain (WG), condition factor (CF), and feed efficiency (FE) were significantly affected by diet×temperature interaction (P<0.05). Specific growth rate (SGR) was significantly affected by increasing temperature (P<0.05). The plant protein-based diets led to a higher CF than the mixed fishmeal/plant protein-based diets. The protein productive value (PPV), protein efficiency ratio (PER), lipid efficiency ratio, (LER) and lipid productive value (LPV) were all significantly affected by diet×temperature interaction (P<0.05). The diet×temperature interaction also had significant effects on mitochondrial enzyme complexes II, V and citrate synthase in the liver, complexes II and IV in the intestine, and complex IV in the muscle (P<0.05). Temperature had a significant main effect on the activity of the enzymatic complexes I and III in the liver, complex III and citrate synthase in the intestine, and complexes I, II, III, V and citrate synthase in the muscle (P<0.05). Diet had a significant main effect on complexes I and III in the liver, complexes II and III for the intestine and complexes I and II in the muscle (P<0.05). The significant temperature x diet interaction observed has practical ecological implications explicitly demonstrating how changes in temperature regimens as anticipated in the rising global temperature can influence organismal performance in relation to changes in dietary formulations (replacing fishmeal based diet with plant protein based ingredients). To illustrate the practical application of the observations from this study, the most economical and cost effective way to produce rainbow trout would be to use 40/10PP diet at 14°C because fish fed this treatment had a weight gain comparable to that of the fish fed the more expensive experimental diets (40/10 FM/PP, 40/20 FM/PP, and 40/20 PP).

Preliminary evidence of the contribution of the intestinal microflora to biotin supply in zebrafish Danio rerio (Hamilton-Buchanan).

A study was conducted to preliminarily assess the contribution of the intestinal microflora to biotin supply in zebrafish. Biotin and avidin were added to three isonitrogenous and isocaloric purified diets to provide molar avidin: biotin ratios of 0:0 (basal diet), 0:1 (biotin-supplemented diet), and 120:0. Another diet was made by supplementing the antibiotic succinylsulfathiazole (1%, wt/wt) to the basal diet. A fifth diet was the Zeigler commercial diet for zebrafish. Each diet was fed to a triplicate group of fish (mean initial mass 0.266 g) for 8 weeks. The condition factor, feed conversion ratio (FCR), percentage weight gain, and survival were similar in fish groups fed the commercial and the biotin-supplemented diets, but energy conversion efficiency and whole-body biotin content were highest in the fish fed the commercial diet (p<0.05). Reduced growth and survival, and increased FCR were noted in fish fed basal diet compared with those fed biotin-supplemented diet. The supplementation of avidin in diet led to lower survival and condition factor, and higher FCR than that observed with basal diet. Intestinal microbial synthesis is assumed to be a significant source of biotin to the zebrafish, as fish fed the antibiotic-supplemented diet showed the lowest growth, health condition, and feed utilization.

Effects of dietary biotin and avidin on growth, survival, feed conversion, biotin status and gene expression of zebrafish Danio rerio.

A study was conducted to investigate the effects of dietary avidin on growth, survival, food conversion, biotin status and gene expression of zebrafish (Danio rerio Hamilton-Buchanan) juveniles (average wet mass 0.178 g) fed 7 purified diets for 12 weeks. Experimental diets were formulated to provide 0×, 1×, 15×, 30×, 60× and 120× excess avidin versus biotin kg(-1) diet, on a molar basis; a control diet contained neither supplemental biotin nor avidin. Fish fed the control diet had the lowest percentage weight gain and the highest mortality, while the highest percentage weight gain and the lowest mortality was observed with the 0× diet (P<0.05). A linear relationship was observed between feed conversion ratio (FCR) and dietary avidin (r=0.876; P<0.0001). Fish fed diets with 120× more avidin than biotin had the highest whole-body biotin content, while the lowest value was obtained with the control and avidin-free diets (P<0.05). Elevated levels of acetyl CoA carboxylase-A (acca), methylcrotonyl CoA carboxylase (mcc) and propionyl CoA carboxylase-A (pcca) transcripts were recorded in fish fed the control diet, in comparison to the other diets. A broken-line analysis indicated that feeding zebrafish a diet with 60 times more avidin than the dietary biotin requirement level will cause biotin deficiency signs.