Taurine (Tau) is a free conditionally essential amino acid for most fish species that plays a significant nutritional role, mainly in carnivorous fish species. However, limited studies are still ...available regarding the role of Tau on pirarucu nutrition, an important Amazonian fish species. Therefore, this study used diets high in plant-based ingredients to investigate the effect of taurine (Tau) supplementation on juvenile pirarucu's growth, metabolism, and health (n = 115, Weight = 504.12 ± 19 g). Fish were fed five diets containing increasing levels of Tau: 0.95, 5.1, 9.6, 12.9, and 17.2 g/kg in a completely randomized design with three replicates per treatment. After a 60-day feeding trial, growth, hematology, blood chemistry, Tau content in muscle, carcass, and liver, antioxidant status, and immunological parameters were evaluated. The control group (0.95 g/kg Tau) showed the lowest growth. According to the segmented regression model, the recommended Tau level for maximizing the development of juvenile pirarucu was 4.49 g/kg of feed. Additionally, fish fed the lowest dietary Tau level showed the highest ROS (reactive oxygen species) concentration. Dietary Tau levels did not affect hematological parameters and blood chemistry (p > 0.05). Fish fed 9.6 g/kg of Tau showed increased catalase activity, while the control group had the worst result in NBT (nitroblue tetrazolium reduction test). Fish fed with the highest dietary Tau levels (12.9 and 17.2 g/kg) showed increased total serum immunoglobulin concentration. These results suggest that the optimal inclusion level of Tau in diets for juvenile pirarucu is 4.49 g/kg of feed and that this amino acid acts as a mitigator of oxidative stress.
•Pirarucu seems to have a limited ability to synthesize taurine.•Taurine affects the antioxidant status of pirarucu.•Taurine does not affect feed intake in Pirarucu.
In aquaculture production, studies of salmon health and interaction between pathogens and nutrition are of high importance. This study aimed to compare genes and pathways involved in salmon head ...kidney cells and liver cells, isolated from the same fish, towards polyinosinic acid: polycytidylic acid (poly I:C) and lipopolysaccharide (LPS), with and without addition of surplus arginine. Selected transcriptional responses of genes involved in inflammation, polyamine synthesis, oxidation and apoptosis were elucidated.
For the genes related to inflammation, viperin, Mx and Toll like receptor 3 (TLR3), transcription were significantly upregulated by poly I:C in head kidney cells, while viperin was upregulated in liver cells. Surplus arginine did not affect poly I:C induced responses with the exception of reducing poly I:C induced Mx transcription in head kidney cells. Gene transcription of Interleukin 1β (IL-1β), Interleukin-8 (IL-8) and cyclooxygenase 2 (Cox2) were elevated during LPS treatment in all liver and head kidney cell cultures. In addition, LPS induced significantly, CD83 transcription in liver cells and TNF-α transcription in head kidney cells. Surplus arginine significantly reduced IL-8, Cox2 and TNF-α transcription in head kidney cells. LPS upregulated arginase in head kidney cells while poly I:C upregulated S-adenosyl methionine decarboxylase (SAMdc) transcription in liver cells. This suggests that LPS and poly I:C modulates genes involved in polyamine synthesis. In addition, in head kidney cells, surplus arginine, when cultured together with LPS, increased the transcription of ornithine decarboxylase (ODC) the limiting enzyme of polyamine synthesis. The genes involved with oxidation and apoptosis were not affect by any of the treatments in liver cells, while LPS decreased caspase 3 transcription in head kidney cells. In liver cells, protein expression of catalase was reduced by surplus arginine alone and when challenged with poly I:C. Both liver cells and head kidney cells isolated from the same individual fish responded to LPS and poly I:C, depending on the gene analyzed. Additionally, arginine could modulate transcription of pro-inflammatory genes induced by LPS in salmon immune cells, thus affecting salmon immunity.
•Liver cells and head kidney cells isolated from the same fish responded to LPS and poly I:C.•Surplus arginine reduced LPS induced transcription of IL-8, Cox2 and TNF-α in head kidney cells of salmon.•LPS and poly I:C interferes with genes related to the polyamine synthesis pathway in the cells.•Surplus arginine modulated expression of catalase enzyme in liver cell samples.
Taurine (Tau) has been regarded as a conditional essential nutrient for some fish species. Although its role has been extensively studied in higher vertebrates, limited results are reported with fish ...especially its role on reproductive performance and the ontogenic changes on Tau levels throughout the life cycle. Therefore, we designed a feeding trial using zebrafish as a model species to test whether Tau supplementation to plant protein diets would have a positive effect on growth and reproductive performance. Zebrafish were fed plant protein diets containing graded levels of Tau (0.2, 4.6, 5.9 and 13.7 g/kg diet) from 10 days post fertilization (dpf) to sexual maturity. An additional commercial diet was used as a positive control for performance. The trial followed a completely randomized design with five treatments (diets) and three replications. After 60 days of feeding, growth, Tau concentration in the body, redox status, lipid body composition, reproductive and offspring performances were analysed. Tau supplementation did not affect growth and/or reproductive performance; however, zebrafish seems to differently modulate Tau concentration according to the growth stage. Tau seemed to induce a hypolipidemic effect in zebrafish by reducing lipid accumulation in their bodies (p < .05). A trend to a more pro‐oxidant effect of Tau supplementation was observed by the decreased reduced glutathione levels. In sum, Tau does not affect growth and reproductive performance of zebrafish but it is important for normal lipid utilization and redox status.
Vitamin A (vitA) is an essential nutrient that acts as an endocrine regulator of several metabolic pathways, modulating normal growth and health status of animals. Although the importance of vitA for ...normal haematology and immune response is well documented for higher vertebrates, there is limited information on the physiological effects of vitA on fish. Therefore, we designed a 130‐day feeding trial to evaluate the effect of vitA supplementation on growth, haematology, immune function and resistance to experimental infection with Aeromonas hydrophila and cold‐induced stress. A group of 320 Nile tilapia fingerlings 7.49 ± 0.19 g weight (mean ± SD) were randomly stocked into 40 250 L‐aquaria and fed practical diets containing graded levels of vitA (0, 0.06, 0.12, 0.24, 0.48, 0.96, 1.92, 3.84 mg retinol (ROH) kg−1 diet. Growth, haematology, plasma protein profile and immune response were significantly affected by vitA supplementation; however, no clear protective effect of vitA supplementation on disease and cold stress resistance were observed in this study. Clinical signs of vitA deficiency were: resting and abnormal swimming behaviour, exophthalmia, haemorrhages at the base of fins and on skin, serous fluids in abdominal cavity, neutropenia, reduction in red blood cell count, haematocrit and haemoglobin evolving to high mortality rates in a short period of time. A dietary level of vitA around 1.2 mg ROH kg−1 may be required to prevent gross deficiency signs and promote proper growth and health status of Nile tilapia. VitA does not seem to have a pronounced effect on leucocyte differentiation, but clearly plays an important role on maintaining normal erythropoiesis.
Available phosphorus (AP) requirement for tambaqui (Colossoma macropomum) was evaluated using different response parameters, and CT scanning was used to determine the adequacy of dietary P along with ...bone mineralization data. A total of 192 tambaqui juveniles (17 ± 0.85 g) were stocked into 24 70 L‐tanks using randomized block design (different floors) with six treatments (1.3, 2.4, 4.8, 6.3, 7.8 and 8.8 g kg−1 AP) and four replicates. Fish were fed ad libitum with six semi‐purified diets containing graded levels of AP for 90 days. The dietary AP requirement was estimated using non‐linear regression models. No mortality or apparent signs of P deficiency were observed. Increasing dietary AP levels improved all performance variables. Dietary P levels significantly affected bone density. The estimated P requirement for tambaqui was 6.3, 3.68, 5.0 and 6.91 g kg−1 diet for improved weight gain, bone density, vertebrae mineralization and carcass mineral deposition, respectively. CT scanning allowed the visualization of bone structures affected by P deficiency and could predict the P requirement based on vertebrae mineralization. Additionally, blood chemistry parameters were significantly affected by the dietary P level, except for serum calcium. Thus, the use of 6.3 g kg−1 AP in tambaqui diets can maintain normal growth and bone mineralization of juveniles from 17–150 g.
Here we show that selected nutritional feed additives reduce the adverse effects of transport stress on the immune system and hematology of tambaqui. We formulated a control diet to contain normal ...dietary levels of vitamin E (21.6 mg/ kg diet) and C (143 mg/kg), then we added supra levels of these vitamins (vit E – 264 mg/kg and vit C – 1000 mg/kg) to a second diet. Finally, a third diet was produced to contain similar levels of vitamins from diet 2 with 0.1% beta-glucan supplementation. Four hundred thirty-two tambaquis (20.91 g ± 0.27 g) were randomly assigned to 12 aquaria and fed the diets for 15 days; then, all fish were transported for five h and then returned to the aquaria. Blood samples were collected before and after the transport and at the end of the trial (60 days). Transportation significantly increased blood glucose that returned to baseline levels at the end of the trial. However, cortisol seemed to be unresponsive to the stress. Surprisingly, the stress significantly increased the immunoglobulin level after transport. Additionally, the transport markedly reduced the red blood cell count and leukocyte and lymphocytes counts while increasing the control group's neutrophil number. These effects lasted until the end of the trial in the control group. Supra levels of the vitamins and glucan supplementation prevented the decrease in red blood cell and leukocyte count after the stress. Additionally, beta-glucan supplementation induced lower cortisol levels in all the sampling points. However, the effect on the immune parameters was limited, increasing only the lysozyme activity and serum protein levels in the beta-glucan supplemented group and the group fed only the supra levels of vitamins, respectively. In sum, our results indicated that transport for five h induced a limited effect on stress biomarkers. The use of supra levels of antioxidant vitamins alone or in combination with beta-glucan could restore or prevent the adverse effects of stress on hematology and the immune system.
This research aimed to determine the upper limit level of crystalline amino acid (CAAs) inclusion in tambaqui nutrition. Additionally, we investigated the possibility of total replacement of fish ...meal (FM) by soy protein concentrate (SPC). An FM‐based control diet was formulated to meet the known nutrient requirements of tambaqui, and three additional diets were prepared by replacing FM protein with 250, 500, and 750 g/kg nitrogen of CAA mixture. The fifth diet was formulated to completely replace the FM by SPC. A growth and a digestibility trial were performed in a completely randomized design with five treatments and three and four replicates, respectively. The optimum replacement level of FM protein by CAA was 280 g/kg based on daily weight gain (DWG). The apparent digestibility coefficients of the nutrients were higher in fish fed the SPC diet than the fish fed the FM diet. The whole‐body lipid and adiposity significantly declined with the increase of CAA in tambaqui diets. Protein and amino acid retention of tambaqui linearly declined with the increase of CAA. Blood chemistry metabolites were not affected by CAA inclusion. We concluded that the SPC could replace FM in tambaqui diets without affecting growth and nutrient digestibility. CAAs could replace FM intact protein up to 250 g/kg (or 97 g/kg inclusion level) without showing any adverse effect on growth and metabolism of tambaqui.
Based on the importance of tambaqui, Colossoma macropomum, for Latin American aquaculture and the digestibility of minerals for the production of sustainable aquafeeds, we designed a series of trials ...to determine the apparent digestibility coefficients (ADCs) of phosphorus, calcium, magnesium, manganese, and zinc from six protein sources: soybean meal (SBM), corn gluten meal 60 (CGM60), cottonseed meal 40, fishmeal (FM), poultry byproduct meal (PBM), and meat and bone meal (MBM); four cereal grain products: corn, wheat middlings, broken rice (BR), and rice bran (RB); and dicalcium phosphate (DCP). Considerable variation in the ADCs of minerals was observed among the feed ingredients. In general, CGM60, PBM, and RB tended to show the highest ADC values, while SBM, MBM, DCP, and BR showed the lowest ADC values. ADC‐P was markedly lower in animal protein sources and the phosphate source (DCP), while high P digestibility was observed for plant protein sources and cereal grain products. Interestingly, tambaqui seems to be able to digest and absorb minerals from plant ingredients more efficiently than animal proteins and DCP. In light of the correlation between nutrient levels and the ADCs of minerals, physiological mechanisms that regulate mineral uptake, and the nutritional ecology of the species, we hypothesize that tambaqui are able to digest minerals from plant proteins with high efficiency.
Apparent digestibility coefficients (ADCs) provide estimates of nutrient availability in feedstuffs and can be used as a tool for selecting ingredients to compound cost-effective diets for fish. ...Extrusion process is one factor that could influence ADC values. Thus, a digestibility trial was undertaken to evaluate ADC of protein, energy, and dry matter, and apparent amino acid availability (AAAA) in five cereal grain products/by-products (corn, wheat middlings, broken rice, rice bran, and sorghum) in compounded diets for Nile tilapia. Chromic oxide was used as an external inert marker. The digestibility values of energy and dry matter in ingredients, in decreasing order, were highest for broken rice (95.34 and 96.45%), sorghum (82.37 and 87.29%), corn (67.34 and 82.21%), rice bran (57.58 and 55.59%), and wheat middlings (48.94 and 45.88%). Protein digestibility value was higher for corn (72.86%) and the lowest value was observed for sorghum (56.77%), while broken rice, wheat middlings, and rice bran presented values ranging from 63.01 to 66.88%. AAAA values were higher for corn (70.05%) and the lowest methionine and cystine availability values were recorded for wheat middlings and broken rice, respectively. Broken rice appears as one of the most indicated ingredient for using in Nile tilapia diets because of its highest values of nutrient digestibility when compared to the other energetic sources. The use of this information should aid more precise and economic diet formulation for Nile tilapia.
Although goldfish (Carassius auratus) is an important species for the ornamental fish industry, few data are available regarding the nutrient requirement of this species, with emphasis to mineral ...nutrition. Thus, we designed a 45-day feeding trial to evaluate the effect of dietary total phosphorus (P) levels on growth performance and carcass mineral composition of goldfish fingerlings. 210 goldfish with 1.18 + or - 0.04 g were randomly stocked into 30 3L-aquaria in a completely randomized design. Test diets were formulated to contain the following dietary total P levels: 3.5, 6.5, 9.5, 12.5 and 15.5 g kg.sup.-1. Dietary P affected all growth parameters and carcass macrominerals deposition, however, the micromineral carcass composition was not affected. No P deficiency signs were observed throughout the experiment. The linear broken-line model best fitted to daily weight gain, feed conversion ratio, specific growth rate, protein efficiency ratio, P retention, and whole-body P concentration at 8.2, 11.4, 8.2, 11.4, 15.5 and 7.1 g kg.sup.-1 dietary P, respectively. An exponential model best fitted to phosphorus utilization data with an estimated requirement of 8.6 g kg.sup.-1. In sum, the use of total P levels between 7.13 and 11.4 g kg.sup.-1 in goldfish diets seems to meet the requirement for maximum growth, feed utilization and proper whole-body mineralization.
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