Effects of dietary thyme essential oil and prebiotic administration on rainbow trout (Oncorhynchus mykiss) welfare and performance

Dietary rosemary oil with/without zymogen forte improves water quality, growth hormones, immune-physiological response, stress resilience, and health status of Chelon ramada grown in groundwater

With freshwater resources becoming scarce worldwide, mariculture is a promising avenue to sustain aquaculture development, especially by incorporating brackish and saline groundwater (GW) use into fish farming. A 75-day rearing trial was conducted to evaluate fish growth, immune response, overall health, and water quality of Chelon ramada cultured in brackish GW and fed on a basal diet (BD) augmented with rosemary oil (RO) or RO + zymogen forte™ (ZF) as an anti-flatulent. Five treatments were administrated in triplicate: T1: fish-fed BD without additives (control group); T2: fish-fed BD + 0.5 g RO /kg diet; T3: fish-fed BD + 0.5 g RO and 1 g ZF /kg diet; T4: fish-fed BD + 1 g RO /kg diet; T5: fish-fed BD + 1 g RO and 1 g ZF /kg diet. Three hundred fish (8.51 ± 0.01 g/fish) were housed in 15 fiberglass tanks (1500-L tank). The results revealed significant improvements (P < 0.05) in growth performance, survival, growth hormone, and insulin-like growth factor-1. Additionally, there were decreases in the feed conversion ratio (FCR) and the levels of nitrogen by-products (NH4, NH3, and NO2) and pathogenic bacterial counts in the rearing water when fish were fed diets supplemented with RO and RO + ZF. Furthermore, significant reductions in the levels of plasma stress indicators (cortisol, creatinine, and glucose) were detected. In addition, there were significant enhancements observed in the levels of innate immune markers, such as white blood cells, total protein, albumin, and immunoglobulin. The complement system, specifically complement 3 and complement 4, also showed considerable improvements. Furthermore, there were increases in plasma heat shock proteins HSP70 and HSP90, as well as enhanced antioxidant activity. These gains were associated with healthier liver and intestines. The investigation demonstrated that adding 0.5-1 g RO / kg diet or RO + ZF to a C. ramada diet has many benefits, including reducing the levels of nitrogen by-product chemicals and pathogenic bacterial load in GW used in growth tanks. Furthermore, significant improvements were observed in the rates of growth and associated hormones, efficiency of feed utilization, blood indicators, immune function, condition of internal organs (namely the intestine and liver), and overall health of the fish.

Efficacy of Lactobacillus acidophilus and yeast cell wall-derived supplements on immunity responses, growth performance, and disease resistance in Cyprinus carpio juveniles

This study investigated the effects of probiotic Lactobacillus acidophilus (PTCC 1643) (LA) and a commercial yeast cell wall prebiotic (Immunogen®) (IM) on immunoantioxidant, growth, and digestive status, and resistance to Aeromonas hydrophila in Cyprinus carpio juveniles. The fish were fed in five treatments including control (T1), LA1.5 (T2): 1.5 (× 10^8 CFU/g of LA)/kg diet, LA3 (T3): 3 (× 10^8 CFU/g of LA)/kg diet, IM1 (T4): 1 g of IM/kg diet, and IM2 (T5): 2 g of IM/ kg diet. After 60 days, the function of growth and intestinal protease and amylase showed a significant increase in IM treatments. Serum levels of total protein and superoxide dismutase in LA3 treatment, as well as albumin, catalase, and glutathione peroxidase in LA3 and IM2 treatments were significantly increased. Serum level of malondialdehyde in LA and IM treatments, as well as alkaline phosphatase (ALP) in LA treatments, alanine aminotransferase in LA and IM2 treatments, and lactate dehydrogenase in LA3 treatment was significantly decreased. Serum levels of all the immune parameters in LA3 treatment, as well as alternative complement pathway hemolytic and nitroblue tetrazolium in IM2 treatment were significantly improved. Mucosal level of protease in LA3 and IM2 treatments, total immunoglobulin, and lysozyme in LA and IM2 treatments, as well as ALP and peroxidase in LA3 treatment was significantly increased. Cumulative mortality rate in LA and IM treatments was significantly decreased compared to control after the 14-day challenge with A. hydrophila. It is recommended to include IM2 in the diet of C. carpio juveniles with regard to its beneficial effects on growth and immunity status.

The effects of dietary supplementation of ginseng stem and leaf saponins on the antioxidant capacity, immune response, and disease resistance of crucian carp, Carassius auratus

This is the first study to explore the positive effects of ginseng stem and leaf saponins (GSLS) on antioxidant capability, immunity, and disease resistance of crucian carp. Seven hundred fifty crucian carps (initial body weight: 25 ± 0.15 g (mean ± SE)) were randomly allocated into five groups with three replicates each; five diets supplemented with the final concentration of 0, 1, 2, 4, and 8 g/kg GSLS were fed to crucian carp for 5 weeks. The results demonstrated that, at a concentration of 8 g/kg, the contents of IgM, C4, SOD, GSH-Px, and the activity of AKP in serum of crucian carp gradually increased at 7, 14, 21, 28, and 35 days, and the expression of immune-relative cytokine genes (TNF-α, IL-10, IFN-γ) in the liver, spleen, and the intestinal tract also had a significant up-regulation (P < 0.05), and which were significant difference compared with control (P < 0.05). The above results demonstrated that dietary GSLS showed enhancement effects on the antioxidant and anti-inflammatory capability, and innate immune response of crucian carp. The feed of 8 g/kg GSLS for 1 week could improve the survival rate 44% more than the control group when crucian carp infected Aeromonas hydrophila (A. hydrophila). In conclusion, the addition of GSLS at a concentration of 8 g/kg in the diet improve immune-related enzyme activity better, immune-relative cytokine expression, and disease resistance.

Enhancing Florida red tilapia aquaculture: biofloc optimization improves water quality, pathogen bacterial control, fish health, immune response, and organ histopathology across varied groundwater salinities

Freshwater scarcity poses challenges to aquaculture worldwide, including countries like Egypt. In this study, we investigate the feasibility of integrating underground saline water (USW) with varying salinities into a Biofloc (BFT) system for desert mariculture of Florida red tilapia (FRT) and its impacts on water quality, fish performance and health. Four BFT treatments (C/N ratio = 15) were examined in triplicate using four salinity levels 0 ppt, 12 ppt, 24 ppt and 36 ppt, expressed as S0, S12, S24 and S36, respectively. For 75 days, a total of 12 fiberglass tanks (each 250 L-1 water) were used to store FRT fry (average weight of 1.73 ± 0.01 g/fish). The fish were fed an experimental diet (protein/fat = 30/5) and an additional carbon source of rice bran. The results revealed that group S12 showed better growth indicators, higher survival rate, lower FCR, and lower ammonia levels, while group S0 exhibited lower growth indicators (final weight, weight gain, and specific growth rate) than all groups. The serum kidney, liver, and antioxidant indices performed better in the S12 group. At 12 ppt, the immune-related parameter (IgM) increased by 22.5%, while the stress parameter (cortisol) decreased by 40.8% compared to the S0 group. The liver and intestinal histopathological results revealed that the S12 and S24 groups performed better. Pathogenic bacterial load counts favored the S24 group, which had the lowest number among the groups studied. The recommended salinity for FRT cultivation in USW and BFT is 19.94-20 ppt, determined by polynomial regression of FW and FCR.

Protective effects of Allium jesdianum essential oil on rainbow trout (Oncorhynchus mykiss) exposed to sub-lethal toxicity of cypermethrin

This study aimed to investigate the protective effects of Allium jesdianum essential oil (AJEO) in decreasing cypermethrin toxicity for rainbow trout. First, the safety of the 0%, 0.5%, 1%, and 1.5% AJEO supplements was assayed after 60 days. Then, the protective effects of AJEO were studied on fish exposed to 12.5% 96h LC50 cypermethrin after 14 days. Results showed that 1 and 1.5% AJEO administration enhanced protease and lipase activities in the intestine and improved growth performance. Moreover, feeding fish with 1 and 1.5% AJEO increased catalase (CAT) and superoxide dismutase activities (SOD) and decreased malondialdehyde (MDA). Also, AJEO increased glutathione peroxidase (GPx) activity in serum. However, exposure to cypermethrin significantly decreased these enzyme activities and increased MDA. The oxidative biomarkers remained normal in fish fed with AJEO after exposure to cypermethrin. The administration of 1 and 1.5% AJEO significantly decreased cortisol and glucose levels, alkaline phosphatase (ALP), lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase activities. Although exposure to cypermethrin significantly increased these biochemical biomarkers, AJEO could adjust them. A significant effect of 1% AJEO on total protein and globulin was observed before and after exposure to cypermethrin. Exposure to cypermethrin decreased all immunological parameters in the serum and mucus. However, administration of 1% AJEO increased protease, lysozyme (LYS) activities, total immunoglobulin (Ig), complement C3 and C4, and nitroblue tetrazolium (NBT) in the serum and ALP, LYS, protease activities and Ig in mucus. In conclusion, results showed that AJEO could potentially decrease the toxicity effects of cypermethrin in fish.

Synergetic response on herbal and probiotic applications: a review

Herbs and their by-products are important traditional medicines and food supplements; they provide numerous beneficial effects for animals. Consequently, probiotics are living cell organisms, nontoxic, and friendly microbes. Probiotics have numerous beneficial activities such as inhibition of pathogens, enhancement of the immune system, growth, disease resistance, improving water quality, reducing toxic effects, synthesis of vitamins, prevention of cancer, reduction of irritable bowel syndrome, and more positive responses in animals. Herbal and probiotic combinations have more active responses and produce new substances to enhance beneficial responses in animals. Herbal and probiotic mixture report is still limited applications for animals. However, the mechanisms by which they interact with the immune system and gut microbiota in animals are largely unclear. This review provides some information on the effect of herbal and probiotic blend on animals. This review discusses current research advancements to fulfill research gaps and promote effective and healthy animal production.

Evaluation of whey protein coating containing nanoliposome dill (Anethum graveolens L.) essential oil on microbial, physicochemical and sensory changes of rainbow trout fish

The aim of this study was to investigate the effect of whey coating containing dill (Anethum graveolens L.) essential oil nanoliposome on the physicochemical, microbiological and sensory characteristics of rainbow trout (Oncorhynchus mykiss). Treatments comprise: sample without coating (control), coating containing whey, coating containing whey with essential oil (whey-EO) and coating containing whey with nano EO (whey-NEO). The particle size, zeta potential, polydispersity index and the encapsulation efficiency were ranged from 142 to 159 nm, -16.3 to -11.7 mV, 0.79 to 0.88 Mw/Mn and 45.85-70.01 %, respectively. Microbial analysis, after 21 days, the maximum and minimum of TVC (total viable counts), TPC (total psychrophilic counts) and LAB (lactic acid bacteria) counts were related to control (8.16 for TVC, 8.46 for TPC and 7.7 log CFU/g for LAB) and whey + NEO (7 for TVC, 7.3 for TPC and 6.16 log CFU/g for LAB), respectively. Also, results of pH, peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and total volatile base-nitrogen (TVB-N) after 21 days were ranged from 6.3 (whey-NEO) to 7.5 (control), from 11.5(whey-NEO) to 20.9 mEq/Kg (control), from 5.23(whey-NEO) to 8.34 mg MDA/kg (control) and from 22.5 (whey-NEO) to 37 mg N/100 g (control), respectively. Finally, in all sensory evaluation items (texture, off-odor, discoloration and red color), the best result after 21 days was related to whey-NEO (score = 1). Consequently, the edible coating comprising whey and nanoliposome of EO could be effective to the maintenance of fish's microbiological, physicochemical, and sensory properties.

Dietary supplementation with Lippia sidoides essential oil improves organ integrity but the specific activity of antioxidant enzymes is dose-dependent in Danio rerio

The nutritional quality of food can affect the health of animals. This study examined the effects of dietary supplementation with Lippia sidoides essential oil (LSEO) on the physiology of Danio rerio. Four hundred fourty-eight fish were divided into 28 tanks and subjected to different dietary treatments: a control group with no supplementation, a group with grain alcohol supplementation and five groups with LSEO at concentrations of 0.25%, 0.50%, 0.75%, 1.00% and 1.25%. After 15 days, histological and enzymatic analyses were conducted. The 0.25% LSEO group exhibited lower glutathione peroxidase and catalase activity compared to the 1.00% group. Additionally, fish in the 0.25% LSEO group showed improved liver, kidney and splenic integrity indices. These findings support the inclusion of 0.25% LSEO in the diet of D. rerio, suggesting potential benefits for fish physiology and encouraging further research on phytotherapeutics in fish diets.

Effects of Dietary Medlar (Mespilus germanica L.) Extract on Growth Performance, Innate Immune Characteristics, Antioxidant Status, and Responses to Crowding Stress in Rainbow Trout (Oncorhynchus mykiss)

High stocking density is a stress factor that potentially affects physiological and immune responses. In this study, the effects of medlar (Mespilus germanica) extract (ME) supplementation on growth performance, antioxidant, immune status, and stress responses in rainbow trout (Oncorhynchus mykiss) were studied. Six hundred fish (40.19 ± 1.09 g; average fish weight ± standard error) were distributed randomly into five experimental groups (assayed in triplicates). The experimental diets were formulated as follows: 0 (T1, control), 0.5% (T2), 1% (T3), 1.5% (T4), and 2% (T4). After 60 days feeding trial, the fish were confined, and the density increased (60 kg/m3) for further 14 days. Results showed significant increases in final weight (FW), weight gain (WG), specific growth rate, and feed intake in the T4 compared to the control (P < 0.05). The feed conversion ratio (FCR) in T4 significantly decreased compared to the control (P < 0.05). Also, the treated groups showed significant improvements in catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), lysozyme (LYZ), total immunoglobulin (total Ig), respiratory burst activity (RBA), total protein, and phagocytosis (PHA) (P < 0.05). Moreover, compared with the control group, supplementation could significantly decrease glucose (GLU) and cortisol (CORT), alanine transaminase (ALT), lactate dehydrogenase (LDH), aspartate transaminase (AST), and alkaline phosphatase (ALP) (P < 0.05). After the challenge, FW and WG in all treated challenge groups were significantly improved compared to the control group (P < 0.05). FCR showed a significant decrease in all treated challenged groups compared to the control group (P < 0.05). However, malondialdehyde, CAT, GPx, SOD, LYZ, complement activity (C3 and C4), total Ig, RBA, peroxidase, and PHA in challenged treated groups were significantly increased compared to the control group (P < 0.05). All treated challenged groups showed lower ALT, LDH, AST, ALP, GLU, and CORT levels than the control group (P < 0.05). The experiment herein successfully demonstrated that dietary ME stimulated fish growth, antioxidant status, and immune responses in crowding conditions and can be recommended as beneficial feed additives for rainbow trout.

Dietary flaxseed (Linum usitatissimum) oil supplementation affects growth, oxidative stress, immune response, and diseases resistance in rainbow trout (Oncorhynchusmykiss)

This paper describes the effects of flaxseed (Linum usitatissimum) oil (FSO) as a feed additive on growth performance, oxidative stress, immunity, and disease resistance in rainbow trout (Oncorhynchus mykiss). Four-hundred-and-twenty rainbow trout individuals (mean weight: 25.66 ± 1.33 g) were fed with different doses of FSO (0.5, 1, and 1.5%) ad libitum two times a day for 9 weeks. At the end of the feeding, growth performance was evaluated and the fish were challenged with two different bacteria (Yersinia ruckeri and Aeromonas hydrophila). At the end of the 3rd, 6th, and 9th weeks, blood and tissue samples were collected from 9 fish per treatment to evaluate innate immune response, cytokine gene expression levels, antioxidant enzyme activities and lipid peroxidation levels, and digestive enzyme activities. Determination of haematological parameters and histological examination was also carried out to evaluate the general health status of the fish. Results showed that the final weight and specific growth rate of fish supplemented with FSO increased significantly (p < 0.05). FSO-supplemented fish showed higher resistance to Y. ruckeri infection than the control group (p < 0.05). However, survival rates of all groups in A. hydrophila challenge test were similar (p > 0.05). Among the investigated innate immune response parameters, the potential killing activity of phagocytes, myeloperoxidase activity, and lysozyme activity increased in the FSO-supplemented groups (p < 0.05). Almost all cytokine gene expression levels in the experimental groups up-regulated especially after 9 weeks of feeding in the head kidney and intestine (p < 0.05). Similarly, superoxide dismutase and catalase activities were found to be significantly higher in the FSO group than in the control (p < 0.05) whereas, the lipid peroxidation levels drastically declined as a result of the FSO supplementation (p < 0.05). These results suggest that FSO can improve growth, enhance immune response, and lower oxidative damage in rainbow trout when supplemented at the rates of 0.5-1.5% for 9 weeks.

Effect of Different Levels of Chlorogenic Acid on Growth Performance, Immunological Responses, Antioxidant Defense, and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss) Juveniles

The current study is designed to assay the efficacy of chlorogenic acid (ChA) in the diet on growth performance, digestive enzyme activity, serum immunological, biochemical, and antioxidant variables, and mucosal immune response as well as disease resistance of rainbow trout (Oncorhynchus mykiss) juveniles. Rainbow trout juveniles received diets supplemented with different inclusion levels of ChA (0 (ctrl), 200 (CA1), 400 (CA2), 600 (CA3), and 800 (CA4) mg kg-1 diet) for 60 days. According to the findings, fish from CA3 and CA4 groups demonstrated the best results considering the final weight (FW) and weight gain (WG) (P < 0.05). Also, the group that received 600 mg kg-1 ChA-supplemented diet showed the lowest feed conversion ratio (FCR) and the highest specific growth rate (SGR) compared to other groups (P < 0.05). Moreover, the minimum survival rate (SR) was only detected in the CA4 treatment (P < 0.05). Regression analysis exhibited that rainbow trout growth indices were polynomially linked to dietary chlorogenic acid concentrations. In this regard, the optimal levels of chlorogenic acid according to growth parameters (FCR and SGR) were 0.71 and 0.62 gr kg-1 diet, respectively. The results exhibited superior performance of protease and amylase activities in CA2, CA3, and CA4 groups with the maximum amount in the group receiving 600 mg kg-1 ChA-enriched diet (P < 0.05). Serum lysozyme (LYZ), immunoglobulin (Ig), and components 3 and 4 (C3 and C4) values of CA2, CA3, and CA4 groups were significantly higher than others with the highest amount in the CA3 group (P <0.05). Additionally, serum nitroblue tetrazolium (NBT) value in the CA3 and CA4 groups and myeloperoxidase (MPO) in the CA3 group were notably more than others (P < 0.05). Moreover, the lowest aspartate aminotransferase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) and the highest total protein (TP) and globulin (GLO) values were observed in CA3 treatment (P < 0.05). CA2 and CA3 groups demonstrated increased serum catalase (CAT) and decreased malondialdehyde (MDA) values compared to the control while the highest CAT and lowest MDA values were observed in CA3 treatment (P < 0.05). Considering mucus immunity, the significantly maximum LYZ and protease values were demonstrated in CA2 and CA3 groups, and the highest ALP, Ig, and esterase values were demonstrated in the CA3 group. In comparison with the control, the mortality rates of the groups that received the ChA diets were remarkably (P < 0.05) lower postchallenge with Y. ruckeri, and the highest survival and relative percentage of survival (RPS) (P < 0.05) belonged to the CA3 group. Results obtained from the current study suggested ChA as a functional dietary additive to raise growth parameters, immune indices, antioxidant capacity, and resistance to disease in rainbow trout.

Comparative Effect of the Active Substance of Thyme with N-Acetyl Cysteine on Hematological Parameters and Histopathological Changes of Bone Marrow and Liver in Rat Models of Acetaminophen Toxicity

Acetaminophen has always been at the center of attention as a non-steroidal anti-inflammatory drug, which is generally associated with the serious side effects on liver and the hematological parameters. This study aimed to compare the effect of N-acetyl cysteine (NAC) and thyme extract on rat models of acetaminophen-induced toxicity. The present experimental study was conducted on 48 Wistar rats randomized into six groups, including the control group (no treatment); the Ac group (470 mg/kg of acetaminophen); the Ac + 100Ex, Ac + 200Ex, and Ac + 400Ex groups (acetaminophen + thyme extract at doses of 100, 200, 400 mg/kg); and Ac + NA group (acetaminophen + NAC). After weighing, a blood sample was taken from heart at the end of the period. The measured parameters were hematological, liver biochemical, and oxidative stress profiles. A part of the liver tissue was also fixed for the pathological examinations. The bone marrow was aspirated to check for cellular changes as well. The lowest mean of the final weight and liver weight to body weight ratio was observed in the Ac group. Weight loss was compensated in Ac + NA and Ac + 200Ex groups (P = 0.035). White blood cell (WBC), red blood cell (RBC), Hemoglobin (Hgb), and Hematocrit (HCT) in Ac and Ac + 400Ex groups showed significant differences from those of the other test groups (P < 0.001). Aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) enzymes in Ac + 200Ex and Ac + NA groups showed a significant decrease compared to those of the other treatment groups (P = 0.043). Total antioxidant capacity (TAC) and glutathione peroxidase (GPx) had the lowest levels in Ac and Ac + 400Ex groups, while malondialdehyde (MDA) had the highest content. In this regard, the liver histopathological indices (necrosis, hyperemia, and hemorrhage) in the Ac + 200Ex and Ac + NA groups reached their lowest grades in the treatment groups. The mean number of erythroid and myeloid cells in the Ac group reached the lowest (17.40 ± 3.48). The microscopic appearance of the bone marrow cells was different from normocytosis in the control group to hypocytosis in the Ac and Ac + 400Ex groups. Thymol, as an effective ingredient in thyme extract at a dose of 200 mg/kg compared to NAC, had a unique effect on reducing bone marrow and liver cell-tissue changes due to the acetaminophen toxicity.

A review on pathogenicity of Aeromonas hydrophila and their mitigation through medicinal herbs in aquaculture

Aeromonas hydrophila is a freshwater, facultatively anaerobic, chemo-organoheterotrophic bacterium that distressed fishes with gastroenteritis, septicemia and causes a disease known as Motile Aeromonas Septicemia (MAS), which affects the aquatic environment. Haemolysin, aerolysin, cytosine, gelatinase, enterotoxin and antimicrobial peptides have been identified as virulence factors in A. hydrophila. Medicinal herbs/plants and their uses are the instant, easily available, cost-effective, efficient and eco-friendly approach for socio-economic, sustainable development of modern aquaculture practice. Phytotherapy either through a dip or by incorporation into the diets is an alternative approach to synthetic pharmaceuticals to diminish the pathogenicity of aquatic environmental pathogens. Due to the presence of remarkable phytoconstituents like flavonoids, alkaloids, pigments, terpenoids, steroids and essential oils, the medicinal plant exhibits anti-microbial, appetite-stimulating, anti-stress, growth-promoting and immunostimulatory activities. Aqua-industry preferred phytotherapy-based techniques/compounds to develop resistance against a variety of aquatic pathogens in culturable fishes because they are inexpensive and environment-friendly. As a result, this review elaborates on the diverse applications of phytotherapy as a promising tool for disease management in aquaculture and a major step toward organic aquaculture.

Dietary Chlorella vulgaris mitigated the adverse effects of Imidacloprid on the growth performance, antioxidant, and immune responses of common carp (Cyprinus carpio)

The use of pesticides to eliminate pests and weeds has raised concerns about water pollution and adverse effects on aquatic organisms, so many efforts have been made to increase the resistance of fish to these pesticides by using a proper nutrition strategy. Therefore, the aim of this study is to investigate the growth performance, antioxidant, and immune responses of fish exposed to Imidacloprid insecticide (C9H10ClN5O2) by different doses of Chlorella vulgaris dry powder to the diet of common carp (Cyprinus carpio). In this study, 600 common carp with a medium weight (18.10±0.2 g; Mean ± SE) were prepared and after adaptation and determination of lethal concentration of Imidacloprid, for 56 days in 6 treatments and each with 3 replications were classified and tested (Control (T1), 5% Chlorella vulgaris dry powder and no pollution (T2), 10% Chlorella vulgaris dry powder and no pollution (T3), No Chlorella vulgaris dry powder and 12.5% LC50 Imidacloprid (T4), 5% Chlorella vulgaris dry powder plus 12.5% LC50 imidacloprid (T5) and 10% Chlorella vulgaris dry powder plus 12.5% LC50 Imidacloprid (T6)). After 96 hours of exposure to distinct concentrations of the insecticide, the total mortality was measured and the Imidacloprid median lethal concentration (LC50) over 96 hours was calculated (266.2 mg/l) using Probit analysis. According to the result, common carp fed T2 had the highest final weight (FW), weight gain (WG), and specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among the groups (P<0.05). Fish in the T2 group had the highest Total proteins, Albumin and Globulin (P<0.05). Fish in the group T4 had the highest Cortisol, Lactate Dehydrogenase (LDH), Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), and Alkaline Phosphatase (ALP) levels in the blood, while fish fed T2 and T3 had low values (P<0.05). The Alternative Complement Pathway (ACH50) was significantly higher in T2 and T3 than other groups (P<0.05). Blood total Immunoglobulin (Ig) and Lysozyme activity were high in T2 and T3 groups, and had the lowest values in the T4 group (P<0.05). The Superoxide Dismutase (SOD), Catalase (CAT) and Glutathione Peroxidase (GPx) showed the highest activities in T2 (P<0.05). T4 group had the highest Malondialdehyde (MDA) level, while T2 and T3 groups had the lowest MDA level (P<0.05). The highest Amylase, Protease and Lipase were in the T2 group, while the lowest values were in the T4 group (P<0.05). In conclusion, dietary Chlorella vulgaris protects common carp from Imidacloprid insecticide, since it improved growth performance, antioxidant and immune responses of fish.

Dietary Thymol Improved Growth, Body Composition, Digestive Enzyme Activities, Hematology, Immunity, Antioxidant Defense, and Resistance to Streptococcus iniae in the Rainbow Trout (Oncorhynchus mykiss)

In this study, thymol (TYM) at dietary levels of 0, 1, 1.5, 2, and 2.5 g/kg diet was used to evaluate its effects on growth, digestive performance, immunity, and resistances to the infection induced by Streptococcus iniae in the rainbow trout, Oncorhynchus mykiss. A number of 450 fish (35.8 ± 4.4 g; Mean ± SD) were distributed to 15 tanks (30 fish/tank) in three replicates and fed TYM for 60 days. After feeding period, Fish fed 1.5-2.5 g TYM showed better growth, higher digestive enzyme activity, and body protein content compared to other diets (P < 0.05). Regression analysis indicated a polynomial relationship between growth parameters and dietary TYM levels. Based upon the varied growth parameters, the optimum dietary TYM level was 1.89% for FCR. TYM at dietary levels of 1.5-2.5 g significantly enhanced liver antioxidant enzyme activity [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)], immune components in blood [alternative complement activity (C3), total immunoglobulin (Ig), lysozyme activity, bactericidal activity, and total protein], and in mucus [alkaline phosphatase (ALP), protease activity, lysozyme activity, bactericidal activity, and total protein] compared to other diets (P < 0.05). TYM at dietary levels of 2-2.5 g significantly decreased malondialdehyde (MDA) levels compared to other experimental groups (P < 0.05). In addition, use of TYM at dietary levels of 1.5-2.5 g upregulated the expression of the immune-related genes (C3, Lyz, and Ig) (P < 0.05). In contrast, the expression of inflammatory genes, tumor necrosis factor (TNF-α) and Interleukin-8 (IL-8) significantly were downregulated in response to 2-2.5 g TYM (P < 0.05). The hematology of the fish also altered in response to dietary TYM, where the values of corpuscular hemoglobin concentration (MCHC), hemoglobin (Hb), red blood cell (RBC), hematocrit (Hct), and white blood cell (WBC) significantly increased in fish fed 2-2.5 g TYM compared to other diets (P < 0.05). In addition, MCV significantly decreased in response to 2-2.5 g TYM (P < 0.05). After challenge with Streptococcus iniae, the survival rate was significantly higher in fish fed 2-2.5 g TYM compared to other diets (P < 0.05). The results of the present study concluded that TYM in the diet of rainbow trout can improve the fish growth and immunity and increase the resistance of the fish to Streptococcus iniae infection. The results of this study recommend an optimized dietary level of 2-2.5 g TYM for the fish.

UPLC-QTOF/MS Metabolomics and Biochemical Assays Reveal Changes in Hepatic Nutrition and Energy Metabolism during Sexual Maturation in Female Rainbow Trout (Oncorhynchus mykiss)

Mobilization and repartition of nutrients and energy are prerequisites for the normal sexual maturity of broodstock. However, there are few studies on the mechanisms of hepatic nutrients and energy metabolism during sexual maturation in female rainbow trout (Oncorhynchus mykiss). This study investigated hepatic metabolite changes and explored the potential nutritional regulation mechanism between mature and immature female rainbow trout by combining UPLC-QTOF/MS metabolomics and biochemical assays. It was observed that hepatic biochemical assays differed considerably between the two groups, such as glucose, triglycerides, hexokinase, lipase, and aspartate aminotransferase. Liver metabolomics showed that various differential metabolites involved in amino acid and lipid metabolism markedly increased, suggesting the enhancement of lipid metabolism and amino acid anabolism in the liver provides the necessary material basis for ovarian development. Meanwhile, glycogen catabolism and glycolysis hold the key to maintaining organismal energy homeostasis with normal sexual maturation of female rainbow trout. Overall, the results from this study suggested that the liver undergoes drastic reprogramming of the metabolic profile in response to mobilization and repartition of nutrients and energy during the sexual maturation of female rainbow trout. This study further deepened the understanding of the reproductive biology of rainbow trout, and provided the theoretical basis and practical ramifications for nutritional requirements of breeding high-quality broodstock in the artificial propagation of rainbow trout.

The Effect of Thyme Essential Oil on Liver Injuries Caused by Renal Ischemia-Reperfusion in Rats

Liver damage occurs following renal ischemia-reperfusion (RIR) that can cause inflammation and inflammatory cytokines activated after kidney injury. In this study, thyme essential oil (TE) with antioxidant and anti-inflammatory properties was used to reduce liver damage induced by renal IR. 32 male rats were randomly divided into 4 equal groups: (1) control, (2) RIR, (3) RIR+TE, and (4) TE. Rats received TE as a pretreatment at a dose of 0.5 ml/kg for one week. Then, under anesthesia for 45 minutes for ischemia, the kidneys of the animals were closed with clamps, and reperfusion was performed for 24 hours. Animal serum was isolated to evaluate alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) parameters. The liver of rats was examined for the measurement of malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH), glutathione peroxidase (GPX), catalase (CAT), and expression of genes such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and caspase-3. ALP, AST, ALT, MDA, NO, IL-6, TNF-α, and caspase-3 increased significantly in the RIR group compared to the control group (p < 0.05). GSH, GPX, and CAT decreased significantly in the RIR group compared to the control group (p < 0.05). TE caused a decrease in ALP, AST, ALT, MDA, NO, IL-6, and TNF-α compared to the RIR group and caused an increase in the amount of GSH, GPX, and CAT in the RIR group (p < 0.05). This study showed that TE has antioxidant and anti-inflammatory properties that reduce liver damage induced by RIR.

Potential protective effects of Thyme (Thymus vulgaris) essential oil on growth, hematology, immune responses, and antioxidant status of Oncorhynchus mykiss exposed to Malathion

As an abundant source of antioxidants and diet flavor enhancers, the plant essential oils can have positive effects on fish growth, and resistance against environmental stressors. In this study, garden thyme (Thymus vulgaris) essential oil (TEO) was used in the diet of rainbow trout, Oncorhynchus mykiss, to evaluate its protective effect against Malathion pesticide exposure. Tested fish (19.99 ± 0.01 g) were divided into six groups (three replicates), namely: T1: control diet; T2: control diet + 0.025 mg L−1 malathion; T3: control diet + 0.075 mg L−1 malathion; T4: control diet + 1% TEO; T5: control diet + 0.025 mg L−1 malathion + 1% TEO and T6: control diet + 0.075 mg L−1 malathion + 1% TEO. After 21 days, T4 fish had the highest final body weight (FW), weight gain (WG), specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among experimental treatments (P<0.05). The blood parameters including the red blood cells (RBC), white blood cell count (WBC), hematocrit (Hct), and hemoglobin (Hb) values were the highest in T4 treatment, displaying a significant difference with T1 treatment (P<0.05). Fish in the T4 groups had the highest total protein (TP) and albumin (ALB), while fish of T3 showed the lowest levels of these parameters (P<0.05) and also had the highest level of triglycerides (TRG), cholesterol (CHOL), lactate dehydrogenase (LDH), and urea (Ur). Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) enzymes recorded the lowest levels in T4 treatment, which showed a significant difference with T1 group. The catalase (CAT) and superoxide dismutase (SOD) showed the highest activities in T4 treatment, while the lowest SOD and the highest malondialdehyde (MDA) levels occurred in T3 group (P<0.05). Total immunoglobulin (total Ig) level, alternative complement (ACH50) and lysozyme in the serum and skin mucus of T4 treatment of rainbow trout showed the highest activities with a significant difference from groups (P<0.05). From the results of the present study, it can be concluded that 1% of T. vulgaris as a supplement to the diet of rainbow trout can stimulate and improve the immune system of the fish. TEO can have a protective effect against unfavorable effects of malathion and improves the growth of the fish.

The Effects of Dietary Thyme Oil (Thymus vulgaris) Essential Oils for Common Carp (Cyprinus carpio): Growth Performance, Digestive Enzyme Activity, Antioxidant Defense, Tissue and Mucus Immune Parameters, and Resistance against Aeromonas hydrophila

This study evaluated the effects of dietary supplementation of thyme (Thymus vulgaris) essential oil (TVO) on growth performance, digestive enzymes, biochemical parameters, hematological indices, liver enzymes, and pathogen resistance in common carp (Cyprinus carpio). Triplicate groups of fish (15.36 ± 0.10 g) were fed daily with diets supplemented with TVO at 0, 0.5, 1, and 2 percent for 60 days then challenged with Aeromonas hydrophila. The results determined that supplementation of thyme resulted in significantly higher final body weights (FBW) and lower feed conversion ratios (FCR). Furthermore, no mortality was observed in the thyme-supplemented treatments. Regression analysis showed that fish growth parameters were polynomially related to dietary TVO levels. The optimum dietary TVO level, based upon the varied growth parameters, was 1.344 to 1.436%. Digestive enzymes activity, including amylase and protease, significantly increased in fish fed the supplemented diets. The thyme-supplemented diets also significantly increased the biochemical parameters, including total protein, albumin, and acid phosphatase (ACP), compared to the control group. We also observed significant increases in hematological indices, including red blood cells (RBC), white blood cells (WBC), hematocrit (Hct), and hemoglobin (Hb) in common carp fed diets containing thyme oil (P < 0.05). Liver enzymes activity including alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) was also reduced (P < 0.05). Immune parameters, including total protein and total immunoglobulin (total Ig) levels, alternative complement pathway hemolytic (ACH₅₀), lysozyme, protease, and ALP in the skin mucus, and lysozyme, total Ig, and ACH₅₀ in the intestine were higher (P < 0.05) in TVO-supplemented fish. Catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) in the liver were also elevated (P < 0.05) in TVO administered groups. Lastly, thyme-supplementation resulted in higher survival rates after the A. hydrophila challenge compared to the control (P < 0.05). In conclusion, dietary inclusion of thyme oil (1 and 2%) effectively improved fish growth, immune systems, and resistance to A. hydrophila.

Influence of black rice (Oryza sativa L.) bran derived anthocyanin-extract on growth rate, immunological response, and immune-antioxidant gene expression in Nile tilapia (Oreochromis niloticus) cultivated in a biofloc system

This study investigated the effects of dietary supplementation with anthocyanin extracted from black rice bran (AR) on the growth rate, immunological response, and expression of immune and antioxidant genes in Nile tilapia raised in an indoor biofloc system. A total of 300 Nile tilapia fingerlings (15.14 ± 0.032 g) were maintained in 150 L tanks and acclimatized for two weeks. Five experimental AR diets (0, 1, 2, 4, and 8 g kg^-1) with various anthocyanin doses were used to feed the fish. We observed that the growth and feed utilization of fish fed with different dietary AR levels increased significantly after eight weeks (p < 0.05). In addition, the serum immunity of fish fed AR diets was much greater than that of those fed non-AR diets (p < 0.05). However, there were little or no difference in between fish fed AR enriched diets and the control AR-free diet (p > 0.05). After eight weeks, fish fed AR-supplemented diets had significantly higher mRNA transcript levels in immune (interleukin [IL]-1, IL-8, and liposaccharide-binding protein [LBP]) and antioxidant (glutathione transferase-alpha [GST-α] and glutathione reductase [GSR]) genes compared to control fish fed the AR-free diet, with the greatest enhancement of mRNA transcript levels (in the case of IL-8 by up to about 5.8-fold) in the 4 g kg^-1 AR diet. These findings suggest that dietary inclusion of AR extract from black rice bran at 4-8 g kg^-1 could function as a herbal immunostimulant to enhance growth performance, feed consumption, and immunity in Nile tilapia.

Lactobacillus casei (IBRC-M 10,711) ameliorates the growth retardation, oxidative stress, and immunosuppression induced by malathion toxicity in goldfish (Carassius auratus)

Probiotics can functionality improve fish wellbeing and are suggested as antioxidative agents to protect fish from xenobiotics toxicity. Herein, dietary Lactobacillus casei (IBRC-M 10,711) was included in the diets of goldfish (Carassius auratus) to protect against malathion toxicity. Fish (12.47 ± 0.06 g) were randomly allocated to six groups (triplicates), as follows: T1) control; T2) fish exposed to 50% of malathion 96 h LC50; T3) L. casei at 106 CFU/g diet; T4) L. casei at 107 CFU/g diet; T5) fish exposed to 50% of malathion 96 h LC50 + L. casei at 106 CFU/g diet; T6) fish exposed to 50% of malathion 96 h LC50 + L. casei at 107 CFU/g diet. After 60 days, goldfish fed T4 had the highest final body weight (FBW), weight gain (WG), and specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among the groups (P < 0.05). However, the T2 group showed lower FBW, WG, and SGR and higher FCR than fish in T1 (P < 0.05). Fish in the T4 group had the highest blood total proteins, albumin, and globulin, while fish in T2 had the lowest levels (P < 0.05). Fish in the group T2 had the highest triglycerides, cholesterol, cortisol, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) levels in the blood, while fish fed T4 had the lowest values (P < 0.05). The superoxide dismutase (SOD) and catalase (CAT) showed the highest activities in T3 and T4 groups, and the lowest SOD was seen in the T2 group, whereas the lowest CAT was seen in the T2, T5, and T6 groups (P < 0.05). Fish in the T5 and T6 groups had higher glutathione peroxidase (GSH-Px) activities than fish in T1 and T2 groups but T3 and T4 groups showed the highest values (P < 0.05). T2 group had the highest malondialdehyde (MDA) level, while T3 and T4 groups had the lowest MDA level (P < 0.05). Blood immunoglobulin (Ig) and lysozyme activity were significantly higher in T3 and T4 groups and lower in the T2 group than in the control (P < 0.05). The alternative complement pathway (ACH50) was significantly higher in T2, T3, T4, T5, and T6 groups than in the T1 group (P < 0.05). Skin mucus Ig was significantly higher in T3 and T4 groups and lower in the T2 group than in the control (P < 0.05). The highest lysozyme activity, protease, and ACH50 in the skin mucus samples were in the T4 group, while the lowest values were in the T2 group (P < 0.05). In conclusion, dietary L. casei protects goldfish from malathion-induced growth retardation, oxidative stress, and immunosuppression.