Effects of dietary yeast culture on shrimp growth, immune response, intestinal health and disease resistance against Vibrio harveyi

Evaluating the Antimicrobial Efficacy of TroLEAP2 like-27 peptide in golden pompano (Trachinotus ovatus) against Bacterial Pathogens

Amicrobial peptides are crucial components of immune system, acting as the first line of defense against microbial invasion. This study investigated the antimicrobial activity of TroLEAP2 like-27, a novel 27-amino acid peptide derived from golden pompano (Trachinotus ovatus), against Gram-positive Lactococcus garvieae and Staphylococcus epidermidis, and Gram-negative Vibrio alginolyticus and Vibrio harveyi. The 3D structure and helical wheel presentation of TroLEAP2 like-27 were consistent with typical AMP features. The hydrophobic ratio of TroLEAP2 like-27 was 47 %, and its α-helical structure suggested strong antimicrobial potential. The expression levels of the TroLEAP2 like gene in the liver and intestines tissues of T. ovatus were significantly upregulated following infection with L. garvieae and V. harveyi. The peptide induced bacterial agglutination in the presence of Ca2+ and exhibited bactericidal activity with a MIC50 of 60 μM. Transmission electron microscopy (TEM) revealed structural damage to bacterial membranes, while membrane permeability assays showed dose-dependent disruption and depolarization in all tested strains. Additionally, TroLEAP2 like-27 exhibited a potent capacity to interact with and degrade genomic DNA of all tested bacteria. The peptide treatment significantly reduced bacterial loads in the gill, liver, and intestinal tissues of the fish, with histological analysis revealing a remarkable protective effect on the tissues. Furthermore, fish treated with TroLEAP2 like-27 exhibited improved survival rates following bacterial infection. These findings suggest that TroLEAP2 like-27 is a promising antimicrobial peptide with potential therapeutic applications.

Characterization of antimicrobial properties of TroH2A-29 peptide from golden pompano (Trachinotus ovatus)

Antimicrobial peptides (AMPs) are small, potent molecules that serve as a crucial first line of defense across a wide range of organisms, including fish. In this study, we investigated the antimicrobial properties of a novel peptide, spanning residues 52 to 80 of the full-length histone H2A protein, comprising a total of 29 amino acids. This peptide, designated as Histone H2A-29 (TroH2A-29), was derived from the golden pompano (Trachinotus ovatus) and evaluated for its activity against both Gram-positive bacteria, Lactococcus garvieae and Staphylococcus epidermidis, and Gram-negative bacteria, Vibrio alginolyticus and Vibrio harveyi. The expression of TroH2A in the intestines, liver, and gills of T. ovatus was significantly upregulated after bacterial infections with L. garvieae and V. harveyi. The highest expression levels were observed at 48 h post-infection in the intestines and at different time points in the liver and gills. TroH2A-29 exhibited a high hydrophobic ratio (51 %) and formed an α-helical structure, suggesting its potential as an antimicrobial agent. Notably, TroH2A-29 induced significant agglutination of all four bacterial species in the presence of Ca2⁺. TroH2A-29 demonstrated bactericidal effects against L. garvieae, V. harveyi, and V. alginolyticus, with a MIC50 of 60 μM. However, it showed no antibacterial activity against S. epidermidis. Transmission electron microscopy (TEM) revealed that TroH2A-29 caused morphological damage to the bacterial cells, including cell collapse in L. garvieae and shrinkage in V. alginolyticus and V. harveyi. No morphological changes were observed in S. epidermidis. Membrane permeability assays showed that TroH2A-29 increased membrane disruption in L. garvieae, V. harveyi, and V. alginolyticus, but had little effect on S. epidermidis. Additionally, TroH2A-29 caused membrane depolarization in all tested bacterial strains. These findings highlight the potential of TroH2A-29 as a novel antimicrobial peptide with selective bactericidal properties.

Study of carbonate alkalinity-induced hepatic tissue damage in Hefang crucian carp (Carassius auratus) based on transcriptomic analysis

This study investigated the effects of different sodium bicarbonate (NaHCO3) concentrations (0 g/L, 1 g/L, and 3 g/L) on Hefang crucian carp (12.0 ± 1.1 g) over a 96-hour period. The experiment is divided into three groups, each with three replicates, and each replicate contains 30 fish. We employed a comprehensive approach integrating histology, physiological and biochemical assays, transcriptomics, as well as artificial intelligence (AI)-assisted analysis. This multifaceted method allowed us to examine changes in gill and liver morphology, osmoregulation, antioxidant capacity, immune response, and physiological metabolism. Results showed that gill and liver tissue damage increased with rising water alkalinity. Serum sodium (Na+), potassium (K+), blood ammonia, and gill Na+/K+-ATPase (NKA) levels increased significantly (p < 0.05). Hepatic antioxidant enzymes initially increased, then decreased with prolonged stress. Serum and liver immunoenzyme indices were higher in bicarbonate-treated groups compared to controls. Carbonate treatment altered lipid and glucose metabolism in both serum and liver. Transcriptome analysis, enhanced by large language models (LLMs), revealed differentially expressed genes (DEGs) significantly associated with ion binding, transport, apoptosis, and metabolism. In conclusion, excessive carbonate intake in fish alters serum physiological functions and affects hepatic metabolic functions. Crucian carp primarily regulate hepatic antioxidant systems, utilize carbohydrate breakdown for energy requirements, and employ lipids in osmoregulation. This study provides insights into fish adaptation to saline-alkaline environments and offers support for the development of aquaculture in saline-alkaline waters.

Effect of Diets Supplemented With Yeast, Chitin, and Chitosan on the Growth, Immune, and Antioxidant Responses of the Freshwater Prawn Cryphiops (Cryphiops) caementarius

The purpose of the present research was to evaluate the effect of diets supplemented with activated yeast, crude chitin, and chitosan on the growth, immune, and antioxidant response of freshwater prawn Cryphiops (Cryphiops) caementarius. Adult male prawns were kept in individual culture vessels installed in aquarium tanks. The basal diet (control) was supplemented with activated Saccharomyces cerevisiae yeast (60 g/kg), crude chitin (20 g/kg), and chitosan (1 g/kg). Each dietary treatment consisted of three replicates. The diet supplemented with activated yeast causes greater growth, as well as a greater number of total hemocytes (82.54 × 105 cells/mL), semigranular (59 × 105 cells/mL), and granular (18.67 × 105 cells/mL) hemocytes and without atypical hemocytes. Furthermore, a higher number of hemocytes positive for prophenoloxidase (98%), a shorter hemolymph clotting time (42.87 s), a higher activity of acid phosphatase (12.50 U/mL) and glutathione-S-transferase (GST) (0.186 U/mL) were also observed in dietary yeast group. On the contrary, there were no differences in the activity of superoxide dismutase (SOD) enzyme in prawns from any dietary treatment. Results from this research demonstrate for the first time that the diet containing activated yeast increases the growth and immune response of the freshwater prawn through a significant increase in hemocyte and acid phosphatase levels, a decrease in hemolymph clotting time, and a greater number of proPO-positive hemocytes. However, activated yeast is not effective in increasing the activity of antioxidant enzymes SOD and GST. Therefore, the activated yeast diet can be useful to improve the aquaculture production of C. (C.) caementarius and possibly of other commercially important crustaceans.

Effects of solid-state fermentation product of yeast supplementation on liver and intestinal health, and resistance of common carp (Cyprinus carpio) against spring viraemia carp virus

This study aimed to investigate the effects of solid-state fermentation products of yeast (SFPY) on liver and intestinal health and disease resistance of common carp (Cyprinus carpio). A total of 200 common carp with an initial average weight of 2.55 ± 0.004 g were divided into 5 groups (4 replications per group and 10 fish per replication), and were fed with one of five diets, including a control diet and 4 diets supplemented with 2‰ (Y2), 3‰ (Y3), 4‰ (Y4), or 5‰ (Y5) SFPY, respectively, for 8 weeks. Results indicated that, the addition of SFPY to the diet of common carp did not affect the growth performance or survival rate of fish (P = 0.253). Interestingly, with the addition of SFPY, the triacylglycerol (TAG) content of the liver presented a linear decreasing tendency (P = 0.004), with significantly decreased in Y4 and Y5 groups (P = 0.035) compared with control. Serum lipopolysaccharide (LPS) content and diamine oxidase (DAO) activity presented a negative linear relationship with the addition of SFPY (P = 0.015, P = 0.030), while serum lipopolysaccharide binding protein (LBP) content first decreased and then increased (P < 0.001). The total antioxidant capacity (T-AOC) in the intestine of fish increased continuously with increasing SFPY supplementation (P = 0.026), reaching the highest level in Y5 group. The villus height in all experimental groups were significantly higher than that in the control group (P < 0.001). Furthermore, compared to the control, adding 3‰ SFPY to the control diet of common carp significantly increased the relative abundance of Fusobacteria (P = 0.018) and decreased that of Proteobacteria (P = 0.039) at phylum level, and increased the relative abundance of Cetobacterium (P= 0.018) and decreased that of Shewanella (P = 0.013) at genus level. Compared with the control, the relative mRNA expression level of spring viraemia of carp virus N protein (SVCV -n) in the kidney was lower than that of the control group without significance and bottomed out in Y4 group (P = 0.138). In conclusion, dietary SFPY enhanced the SVCV resistance capacity of common carp by improving liver and intestinal health and modulating the gut microbiota. Thus, SFPY is a potential feed additive to be used in aquaculture to reduce the huge economic loss of common carp due to SVCV disease. Based on liver TAG content and intestinal villus height, the optimal addition level of SFPY was 3.02‰ and 2.72‰, respectively.

Effects of dietary salidroside on intestinal health, immune parameters and intestinal microbiota in largemouth bass (Micropterus salmoides)

The largemouth bass has become one of the economically fish in China, according to the latest China Fishery Statistical Yearbook. The farming scale is constantly increasing. Salidroside has been found in past studies to have oxidative stress reducing and immune boosting properties. In this study, the addition of six different levels of salidroside supplements were 0、40、80、120、160 and 200 mg/kg. A 56-day feeding trial was conducted to investigate the effects of salidroside on the intestinal health, immune parameters and intestinal microbiota composition of largemouth bass. Dietary addition of salidroside significantly affected the Keap-1β/Nrf-2 pathway as well as significantly increased antioxidant enzyme activities resulting in a significant increase in antioxidant capacity of largemouth bass. Dietary SLR significantly reduced feed coefficients. The genes related to tight junction proteins (Occludin, ZO-1, Claudin-4, Claudin-5) were found to be significantly upregulated in the diet supplemented with salidroside, indicating that salidroside can improve the intestinal barrier function (p < 0.05). The dietary administration of salidroside was found to significantly reduce the transcription levels of intestinal tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) (p < 0.05). Furthermore, salidroside was observed to reduce the transcription levels of intestinal apoptosis factor Bcl-2 associated death promoter (BAD) and recombinant Tumor Protein p53 (P53) (p < 0.05). Concomitantly, the beneficial bacteria, Fusobacteriota and Cetobacterium, was significantly increased in the SLR12 group, while that of pathogenic bacteria, Proteobacteria, was significantly decreased (p < 0.05). In conclusion, the medium-sized largemouth bass optimal dosage of salidroside in the diet is 120mg/kg-1.

Potential effects of probiotics (immunobacteryne; IMB) on growth performance, feed efficacy, blood biochemical, redox balance, nonspecific immunity and heat-shock protein expression of Nile tilapia (Oreochromis niloticus) fingerlings

The supplementation of aquafeed with probiotics is recommended for feasible aquaculture activities. Therefore, the aim of current study was to investigate the potential effects of probiotics on growth performance, feed utilization, biochemical attributes, redox status and immunity response as well as the transcription of heat-shock protein 70 (HSP70) and insulin-like growth factor-1 (IGF-1) genes of Nile tilapia (Oreochromis niloticus; n = 120). Fish with an initial weight of 8.17 ± 0.02 g/fish were randomly divided into four treatment groups and were fed diets containing 0, 0.5, 1 and 1.5 mg immunobacteryne (IMB)/kg diet respectively. Dietary IMB at 1.5 g/kg diet significantly improved the growth performance, feed consumption and growth hormone secretion of the experimental fish (p < 0.05). The 1 or 1.5 g IMB/kg diet boosted phagocytic activities and innate immune response. Serum total protein, total cholesterol, triglycerides and glucose were significantly increased in the groups that were fed 1 and 1.5 mg IMB/kg diet compared to the control (p < 0.05). Meanwhile, the levels of uric acid, creatinine, liver enzymes (aspartate transaminase and alanine transaminase) and cortisol hormone were significantly reduced in the aforementioned treated groups compared to the control (p < 0.05). All fish fed IMB-supplemented diet showed a significant increase in the expression of IGF-1 gene, while the transcription of HSP70 was significantly decreased (p < 0.05). In conclusion, the dietary inclusion of IMB (1 g/kg diet) enhanced growth promoters, feed efficacy, blood biochemical, redox balance and nonspecific immune responses in Nile tilapia fingerlings.

Saccharomyces cerevisiae supplemented diets mitigate the effects of waterborne cadmium toxicity on gilthead seabream (Sparus aurata L.): growth performance, haemato-biochemical, stress biomarkers, and histopathological investigations

Yeast, Saccharomyces cerevisiae, has been utilized as a probiotic in aqua-feeds to promote growth and alleviate the stress in aquatic animals. On the other hand, cadmium (Cd) toxicity causes serious retardation of growth and welfare status of aquatic animals. The present study was conducted to evaluate the protective role of dietary yeast in mitigating the waterborne Cd toxicity effects on the growth, haemato-biochemical, stress biomarkers, and histopathological investigations of gilthead seabream (Sparus aurata L.). In a 3 × 3 factorial design, the acclimated fish (20-24 g) were randomly distributed into nine treatments in triplicates where they were fed on 0.0% (control), 0.5%, and 1.0% of yeast along with exposure to 0.0, 1.0, and 2.0 mg Cd/L for 60 days. All growth parameters and mRNA expressions of IGF-1 and GH genes as well as haematological parameters were markedly increased with the increase of dietary yeast levels; meanwhile these variables were significantly retarded with Cd exposure. Contradictory effects on the above-mentioned variables were observed with Cd toxicity. In contrast, blood cortisol, glucose, total cholesterol, and triglyceride, lactate dehydrogenase, alanine transaminase, aspartate transaminase, alkaline phosphatase, in addition to DNA fragments % were noticeably increased with Cd toxicity especially at the treatment of 2.0 mg Cd/L, while decreasing with increasing dietary yeast levels. Compared with the control fish group, Cd concentrations in the gill, liver, and muscle tissues of gilthead seabream were higher in Cd-exposed treatments, especially at the treatment of 2.0 mg Cd/L. Deposition of Cd in fish liver was higher than that in gill tissues but lowest Cd residue was observed in muscle tissues. No significant changes in Cd residues in fish organs were observed in yeast-fed fish with no Cd exposure. The Cd exposure negatively affected histological status of gill, liver, and kidney tissues of S. aurata; while feeding Cd-exposed fish on yeast diets lowered the Cd residues in fish organs and recovered the adverse effects of Cd toxicity. Hence, this study recommends the addition of bakery yeast (1.0%) to fish diets to improve the performance, overall welfare, and histopathological status of gilthead seabream, S. aurata.

Effect of fed dietary yeast (Rhodotorula paludigena CM33) on shrimp growth, gene expression, intestinal microbial, disease resistance, and meat composition of Litopenaeus vannamei

Yeast is a health-promoting and bio-therapeutic probiotic that is commonly used in aquaculture. Rhodotorula paludigena CM33 can accumulate amounts of intracellular carotenoids and lipid, which are regarded as nutritionally beneficial compounds in various aspects. The aim of this study was to evaluate the impact of different levels of R. paludigena CM33 (RD) incorporated in a dietary composition at 0% (control), 1% (1% RD), 2% (2% RD), and 5% (5% RD) on the growth of shrimp (Litopenaeus vannamei), their immune-related gene expression, intestinal health, resistance to Vibrio parahaemolyticus (VPAHPND) infection, and meat composition. The results showed significant improvements in the specific growth rate, weight gain, and survival of shrimp fed with 1% RD, 2% RD, and 5% RD, which were higher than the control group after 4 weeks of administration. The administration of 5% RD group resulted in a decrease in cumulative mortality upon VPAHPND challenge when compared to the control group. Furthermore, the expression levels of immune-responsive genes, including proPO system (prophenoloxidase-2: PO2), antioxidant enzyme (superoxide dismutase: SOD, glutathione peroxidase: GPX, and catalase: CAT), JAK/STAT pathway (signal transducer and activator of transcription: STAT, gamma interferon inducible lysosomal thiol reductase: GILT), IMD pathway (inhibitor of nuclear factor kappa-B kinase subunit beta and epsilon: IKKb and IKKe), and Toll pathway (Lysozyme) genes, were up-regulated in the 5% RD group. In the context of microbiota, microbiome analysis revealed that the main phyla in shrimp intestines were Proteobacteria, Firmicutes, Bacteroidota, Campilobacterota, Actinobacteriota, and Verrucomicrobiota. At the genus level, Vibrio was found to be reduced in the 5% RD group, whereas the abundance of potentially beneficial bacteria Bifidobacterium was increased. The 5% RD group showed a significant increase in the levels of crude protein and crude lipid, both of which are essential nutritious components. Our results show the capability of R. paludigena CM33 as a probiotic supplement in shrimp feed in improving growth, antimicrobial responses against VPAHPND, and meat quality by increasing protein and lipid content in shrimp.

Yarrowia lipolytica biomass-a potential additive to boost metabolic and physiological responses of Nile tilapia

We studied the effects of Yarrowia lipolytica biomass on digestive enzymes, blood biochemical profile, energy metabolism enzymes, and proximate meat composition of Nile tilapias. The experiment was entirely randomized with four replications. The animals (n = 20 per repetition) were fed with 0%, 3%, 5%, and 7% of biomass for 40 days and then blood and liver were analyzed. There was an increase in the activities of chymotrypsin (5, 7% groups), trypsin (3, 5% groups), and sucrase (7% group) compared to the respective control groups. On the other hand, maltase activity was significantly reduced for all yeast biomass treatments, while the supplementation did not influence lipase and amylase activities. Moreover, the blood triacylglycerol concentrations were increased in the 7% group, while any treatment modified blood total cholesterol, glycemia, and hepatic glycogen content. Y. lipolytica biomass promoted significant increases in meat protein and lipid contents without changes in moisture and ash parameters. Furthermore, Y. lipolytica biomass promoted increases in hexokinase (3% group), phosphofructokinase (5, 7% groups), glucose-6-phosphate dehydrogenase (5% group), citrate synthase (3% group), aspartate aminotransferase and alanine aminotransferase (3% group), and glutamate dehydrogenase (3, 5% groups) compared to the respective control groups. At the same time, no changes were observed in the activity of glucose-6-phosphatase. Y. lipolytica biomass supplementation in tilapias' diet can modulate the digestive system and improve nutrient disponibility to the cells. Moreover, the changes in the metabolic profile and in energy metabolism can be correlated with the improvement of meat composition. Therefore, the Y. lipolytica biomass has a great potential to be used as a feed ingredient for Nile tilapias.

A comparative study on effects of dietary three strains of lactic acid bacteria on the growth performance, immune responses, disease resistance and intestinal microbiota of Pacific white shrimp, Penaeus vannamei

The present study evaluated the growth performance, immune responses, disease resistance and intestinal microbiota in Penaeus vannamei fed diets supplemented with three strains of lactic acid bacteria (LAB). The basal diet (control, CO) supplemented with Lactobacillus plantarum W2 (LA), Pediococcus acidilactici Nj (PE), Enterococcus faecium LYB (EN) and florfenicol (FL), respectively, formed three LAB diets (1 × 10¹⁰ cfu kg^-1) and a florfenicol diet (15 mg kg^-1, positive control), were fed to shrimp for 42 days. Results indicated that specific growth rate, feed efficiency rate, and disease resistance of shrimp against Vibrio parahaemolyticus in the treatment groups were significantly improved versus the control (P < 0.05). Compared with the control, acid phosphatase, alkaline phosphatase, phenonoloxidase, total nitric oxide synthase, peroxidase, superoxide dismutase activities, total antioxidant capacity, and lysozyme content in the serum and the relative expression levels of SOD, LZM, proPO, LGBP, HSP70, Imd, Toll, Relish, TOR, 4E-BP, eIF4E1α and eIF4E2 genes in the hepatopancreas of LAB groups were enhanced to various extents. Intestinal microbiota analysis showed that the LA and EN groups significantly improved microbial diversity and richness, and LAB groups significantly altered intestinal microbial structure of shrimp. At the phylum level, the Verrucomicrobiota in the LA and PE groups, the Firmicutes in the EN group, and the Actinobacteriota in the PE and EN groups were enriched. Moreover, the CO group increased the proportion of potential pathogens (Vibrionaceae and Flavobacteriaceae). The potential pathogen (Vibrio) was reduced, and potential beneficial bacteria (Tenacibaculum, Ruegeria and Bdellovibrio) were enriched in response to dietary three strains of LAB. When the intestinal microbiota homeostasis of shrimp is considered, L. plantarum and E. faecium showed better effects than P. acidilactici. However, due to the concerns on the possible potential risks of E. faecium strains to human health, L. plantarum W2 is more suitable for application in aquaculture than E. faecium LYB. Considering collectively the above, Lactobacillus plantarum W2 could be applied as better probiotic to improve the growth performance, non-specific immunity, disease resistance and promote intestinal health of P. vannamei.

Effects of Fishmeal Replacement by Clostridium Autoethanogenum Protein Meal on Cholesterol Bile Acid Metabolism, Antioxidant Capacity, Hepatic and Intestinal Health of Pearl Gentian Grouper (Epinephelus Fuscoguttatus ♀ × Epinephelus Lanceolatus ♂)

In this study, we present data from an eight-week growth trial with pearl gentian grouper fed either a reference diet (FM) with a fishmeal level of 50%, or test diet wherein 15% (CAP15), 30% (CAP30), 45% (CAP45), and 60% (CAP60) fishmeal was replaced by Clostridium autoethanogenum protein meal (CAP). Results showed that the weight gain and daily feed intake ratio of CAP60 were significantly lower than the FM group. In the serum, compared to the FM group, the content of malondialdehyde (MDA), the activities of alanine aminotransferase in CAP60 and CAP45 groups, and acid phosphatase in the CAP60 group were significantly higher, while the content of total cholesterol in CAP60 and CAP45 groups was significantly lower. In the liver, compared to the control group, the content of MDA in the CAP60 group was significantly higher. 3-hydroxy-3-methylglutaryl coenzyme A reductase in CAP30 to CAP60 groups and farnesoid X receptor in CAP60 were significantly upregulated. In distal intestines, the activities of trypsin and superoxide dismutase of CAP30 to CAP60 groups were significantly lower than the FM group. In conclusion, for pearl gentian grouper, CAP could replace up to 45% of the fishmeal in the feed, while a 60% replacement level will affect cholesterol bile acid metabolism and health.

Bioconversion of food waste to crayfish feed using solid-state fermentation with yeast

In order to realize the value-added utilization of food waste (FW), the preparation of crayfish (Procambarus clarkii) feed by yeast fermentation was investigated. Firstly, the suitable fermentation condition was obtained through a single factor experiment as follows: the initial moisture of the FW was adjusted to 60% with bran and inoculated with a 2% yeast mixture (Saccharomyces cerevisiae, Candida utilis, and Yarrowia lipolytica, 3:2:1) followed by aerobic solid-state fermentation for 7 days. The crude protein and acid-soluble protein contents in the fermented feed were 25.14% and 5.16%, which were increased by 8% and 140.67%, respectively. The crude fat content was 0.74%, decreased by 68.29%. The content of antioxidant glutathione (571.78 μg/g) increased 63.33%, and the activities of protease and amylase increased nearly 9 and 3 times, respectively. The maximum degradation rates of aflatoxin B1, zearalenone, and deoxynivalenol were 63.83%, 77.52%, and 80.16%, respectively. The fermented feeds were evaluated by substituting (0%, 10%, 30%, 50%, and 100%) commercial diet for crayfish (30-day culture period). When the replacement proportion was 30%, the weight gain of crayfish reached 44.87% (initial body weight 13.98 ± 0.41 g), which was significantly increased by 10.25% compared with the control (p = 0.0005). In addition, the lysozyme and SOD enzyme activities in crayfish hepatopancreas were also increased significantly. Our findings suggest that yeast-fermented feed from FW can replace 30% of crayfish's conventional diet, which may improve crayfish's antioxidant capacity and enhance non-specific immunity by providing molecules such as glutathione.

Supplementing artemisinin positively influences growth, antioxidant capacity, immune response, gut health and disease resistance against Vibrio parahaemolyticus in Litopenaeus vannamei fed cottonseed protein concentrate meal diets

Artemisinin (ART) is a kind of Chinese herbal medicine worth exploring, which obtains various physiological activities. In order to study the prebiotic effect of ART on Litopenaeus vannamei fed cottonseed protein concentrate meal diets, six groups of isonitrogenous and isolipid diets were prepared (including the fish meal control group, FM; cottonseed protein concentrate replacing 30% fishmeal protein and supplementing ART groups: ART0, ART0.3, ART0.6, ART0.9, and ART1.2). The feeding trials was lasted for 56 days. The results showed that the final body weight, weight gain and specific growth rate of the ART0.6 group were the highest, yet the feed coefficient rate of the ART0.6 group was the lowest significantly (P < 0.05). There was no significant difference in survival rate among treatments (P > 0.05). In serum, the content of malondialdehyde in ART0 group was the highest (P < 0.05); the activities of superoxide dismutase, catalase, phenol oxidase and lysozyme increased firstly and then decreased among the ARTs groups (P < 0.05). The activities of intestinal digestive enzymes (including the trypsin, lipase and amylase) showed an upward trend among the ARTs groups (P < 0.05). The histological sections showed that the intestinal muscle thickness, fold height and fold width in the FM group were significantly better than those in the ART0 group; while the mentioned above morphological indexes in the ART0 group were significantly lowest among the ARTs groups (P < 0.05). Sequencing of intestinal microbiota suggested that the microbial richness indexes firstly increased and then decreased (P < 0.05); the bacterial community structure of each treatment group was almost close; the relative abundance of pathogenic bacteria decreased significantly (P < 0.05), such as the Proteobacteria and Cyanobacteria at phylum level, besides the Vibrio and Candidatus Bacilloplasma at genus level. In intestinal tissue, the relative expression levels of TOLL1, TRAF6 and Pehaeidih3 showed up-regulated trends, while the expression of Crustin and LZM firstly up-regulated and then down-regulated (P < 0.05). The challenge experiment suggested that the cumulative mortality of FM group was significantly lower than that of ART0 group; besides the cumulative mortality firstly increased and then decreased between the ARTs groups (P < 0.05). In conclusion, the dietary supplementation of ART can improve the growth, antioxidant capacity, immune response, gut health and disease resistance of the shrimp. To be considered as a dietary immune enhancer, the recommended supplementation level of ART in shrimp's cottonseed protein concentrate meal diets is 0.43%.

Role of Clostridium butyricum, Bacillus subtilis, and algae-sourced β-1,3 glucan on health in grass turtle

This study investigated the effects of two probiotics namely Clostridium butyricum and Bacillus subtilis, and one prebiotic known as algae-sourced β-1,3 glucan, on the overall performances of grass turtles (Chinemys reevesii) juveniles. Growth performance, immune responses, enzymatic antioxidant activities, intestinal histomorphology, and disease resistance against the challenge with Aeromonas veronii were assessed. Two hundred and sixteen (216) juvenile turtles with an average initial weight of 106.35 ± 0.03 g were divided into four groups, each containing three replicates with 18 turtles per each replicate, which were fed a basic diet (control group, GD) and a basal diet supplemented with C. butyricum 1.0 × 10⁸ CFU per kg (GA group), or with B. subtilis 1.0 × 10⁸ CFU per kg (GB group) and with algal-sourced β-1,3-glucan 50 mg per kg (GC group), respectively. After the turtles had been fed for 60 d, 90 d, and 120 d of the experimental period, the growth performance and survival rate (SR), intestinal digestive enzyme, hepatic and intestinal antioxidant capacity, serum biochemical indexes, and immune performance were measured. The results showed that the weight gain rate and SR were significantly enhanced (P < 0.05) after fed probiotics and algae-sourced β-1,3-glucan in all test times;The pepsin, amylase, acid phosphatase, total antioxidant capacity, triglyceride, alkaline phosphatase, urea nitrogen, cholesterol, total protein, IgA, IgG, IgM at 120 d were significantly enhanced (P<0.05) after fed C. butyricum. The intestinal villi heights, widths, and the thickness of the muscle layer were significantly higher in groups GA, GB, and GC than those reared within the GD control group (P < 0.05). After injecting the challenge by A. veronii the survival rate of grass turtles in the GA group (75%) was significantly higher than the other three groups (P<0.05), while there was no significant difference between the GB and GC groups compared with the control GD group, respectively (P>0.05). Overall, these results indicated that dietary supplementation with probiotics or algae-sourced β-1,3 glucan, exhibited positive effects on C. reevesii. In particular, C. butyricum, showed the greatest improvements relating to growth, immune response, antioxidant activity, intestinal health, and disease resistance.

Effects of dietary yeast culture on health status in digestive tract of juvenile Pacific white shrimp Litopenaeus Vannamei

A feeding trial was conducted to investigate the effects of dietary yeast culture (YC) on health status in digestive tract of juvenile Pacific white shrimp Litopenaeus Vannamei. Shrimps (initial weight: 3.33 ± 0.06 g) were fed with graded levels of dietary YC (control, 0.3%, 0.5% and 1.0%). Results of the present study showed that villus height and the ratio between villus height and crypt depth in the digestive tract of juvenile shrimp was significantly increased by dietary 0.5% and 1.0%YC (P < 0.05). Besides, dietary 0.5% and 1.0%YC significantly activities of phenoloxidase (PO), lysozyme (LZ), acid phosphatase (ACP) and alkaline phosphatase (AKP) (P < 0.05), significantly up-regulated mRNA levels of prophenoloxidase (propo), lysozyme (lz), anti-lipopolysaccharide factor (alf), crustin and penaienadin (P < 0.05) and down-regulated mRNA levels of caspase-1, nuclear factor κB p65 (nf-κbp65) myeloid differentiation primary response protein (myd88) and toll like receptor (tlr) in the digestive tract of juvenile shrimp (P < 0.05). Compared with the control, dietary 0.5%YC increased Chao1 index in the digestive tract of juvenile shrimp. In addition, compared with the control, dietary 0.5% and 1.0%YC significantly increased relative abundance of Lactobacillus (P < 0.05). It can be concluded that dietary YC made positive contribution to health status in digestive tract of juvenile shrimp through improving morphology and microbiota, enhancing immune function, and inhibiting inflammation of digestive tract.

Nuclease treatment enhanced the ameliorative effect of yeast culture on epidermal mucus, hepatic lipid metabolism, inflammation response and gut microbiota in high-fat diet-fed zebrafish

As a functional feed additive, yeast cultures are rich in nucleotides, and adding extra nuclease can significantly increase the content of nucleotides in yeast culture. In this experiment, the effects on growth, epidermal mucus, liver and intestinal health of zebrafish were evaluated by supplementing the yeast culture or nuclease-treated yeast culture with a high-fat diet (HFD). One-month-old zebrafish were fed four diets: normal diet (NORM), HFD, yeast culture diet (YC), and nuclease-treated yeast culture diet (YC (N)) for three weeks. Results showed that the complement 4 activity of the epidermal mucus in YC (N) group was significantly higher than those in HFD and YC groups (P < 0.05). The YC and YC (N) significantly reduced the content of hepatic triglyceride caused by HFD (P < 0.05). Moreover, compared with the YC group, the YC (N) significantly increased the expression of lipolysis genes, such as PPARα, PGC1α, ACOX3 (P < 0.05). Compared with the YC group, the YC (N) group significantly increased the expression of liver pro-inflammatory factors TNFα, IL-6, IL-1β and anti-inflammatory factors TGFβ, IL-10 (P < 0.05). The diet YC and YC (N) significantly improved the height of the intestinal villus (P < 0.05). Compared with the HFD group, the YC (N) group significantly increased the expression of intestinal pro-inflammatory factors TNFα, IL-6 and anti-inflammatory factors TGFβ, IL-10 (P < 0.05). The YC (N) group significantly decreased the abundance of intestinal Proteobacteria and Acinetobacter, and increased the abundance of intestinal Actinobacteria, Mycobacterium and Rhodobacter (P < 0.05). In conclusion, compared with the supplement of yeast culture, nuclease treated yeast culture can further alleviate the adverse effects of HFD on liver and intestinal health, and be used as feed additives for the nutritional and immune regulation of fish.

Dietary yeast culture alleviates intestinal-hepatic damage related to TLR2-MyD88-NF-κB signaling pathway and antioxidant capability in Pseudobagrus ussuriensis

Yeast culture (YC), as a member of probiotics family is a natural product produced from yeast fermentation, affects of improving immunity. However, the intestine and liver injury and immunosuppression mechanism caused by SBA in fish are unclear and more functions of YC supplement in the diet need to be developed. Soybean agglutinin (SBA) is an anti-nutritional factor in soybean and leads to growth-inhibitory effect in feeding of the high proportion of soybean meal replacing fish meal (FM). Therefore, one hundred and thirty-five Pseudobagrus ussuriensis (6.5 ± 0.27 g) were randomly selected and divided into three groups (Control, SBA and YC+SBA groups). For the model, fish were fed with 2% YC for 8 weeks and then given intragastric administration of 0.2-mL SBA solution for 20 days. The results showed that SBA damaged the immune and antioxidant capacity, causing an inflammatory reaction, leading to abnormal expression of cytokines in the intestine and liver of Pseudobagrus ussuriensis. YC could effectively attenuate intestinal and liver damage and downregulate the TLR2/MyD88/NF-κB signaling pathway and suppress oxidative stress in Pseudobagrus ussuriensis. Besides, YC had obvious immune advantage, which could improve the immune ability. In summary, these results showed that YC could reduce immunosuppression and intestinal-liver injury by inhibiting the TLR2/MyD88/NF-κB signal pathway and oxidative stress induced by SBA. This study provided some explanations for the problems of fish diet caused by anti-nutritional factors from soybean meal and provided a theoretical basis for the function development of YC in aquaculture.

Rhodotorula benthica culture as an alternative to antibiotics improves growth performance by improving nutrients digestibility and intestinal morphology, and modulating gut microbiota of weaned piglets

The effects of Rhodotorula benthica culture (RBC) and antibiotics (AB) on the growth performance, nutrients digestibility, morphological indicators, and colonic microbiota of weaning piglets were explored. Ninety-six (Duroc × Landrace × Large) weaned piglets (21-day-old) weighing 7.7 ± 0.83 kg, were randomly allocated to 4 dietary treatments. They were fed with basal diet (CON), basal diet + 25 mg/kg bacitracin zinc + 5 mg/kg colistin sulfate (AB), 5 g/kg reduction in soybean meal of basal diet + 5 g/kg RBC (RBC1), or 10 g/kg reduction in soybean meal of basal diet + 10 g/kg RBC (RBC2). The results showed that dietary RBC1 improved the body gain/feed intake (G/F) of weaned piglets than the CON diet, and the RBC2 diet improved the average daily gain and G/F than CON and AB diets from days 15 to 28 (P < 0.05). Supplementation of RBC2 improved the apparent total tract digestibility of dry matter, nitrogen, and gross energy in weaned piglets compared to controls from days 15 to 28 (P < 0.05). Dietary AB, RBC1, and RBC2 enhanced the ileal villus height (VH) and VH/crypt depth (CD), and these two indicators were greater in the RBC2-treated piglets than in the AB- and RBC1-treated piglets (P < 0.05). The activity of serum superoxide dismutase (SOD) was enhanced by dietary AB, RBC1, and RBC2 (P < 0.05). Serum glutathione (GSH) concentration was elevated by dietary RBC1 and RBC2 (P < 0.05). According to 16S rRNA sequence analysis, AB- and RBC2-treated piglets had a higher relative abundance of Firmicutes and Lachnospiraceae in the colon digesta, and more abundant Lactobacillus was found in RBC1-treated piglets, as compared to the CON group. Additionally, RBC2 supplementation increased the α diversity [Chao1, PD-whole-tree, and observed operational taxonomic units (OTUs)] compared to the CON group. Taken together, the dietary RBC improved the growth performance of weaned piglets. In addition, 10 g/kg of RBC2 in the diet achieved better effects on higher ADG, ileal villi morphology, and stronger antioxidant capacity than dietary AB and RBC1 in weaning piglets.

Glycerol monolaurate (GML), a medium-chain fatty acid derivative, ameliorate growth performance, immune function, disease resistance and intestinal microbiota in juvenile hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂)

In order to evaluate the effects of glycerol monolaurate (GML) on the growth performance, immunology function, disease resistance and intestinal microbiota for hybrid groupers. Seven levels of GML (0, 600, 1200, 1800, 2400, 3000 and 3600 mg/kg) were added to diets and were noted as the G1 (control group), G2, G3, G4, G5, G6 and G7, respectively. Each experimental diet was fed to triplicate groups of 30 juvenile groupers for 8 weeks. The FBW, WGR and SGR were significantly higher and FCR was significantly lower in the G4 group compared to the G1 group (P < 0.05). Serum immune enzyme activities (ACP, AKP and LZM) rose and then fell and had the highest values in the G4 group (P < 0.05). The expression of TNF-α and IL6 in head kidney was significantly inhibited (P < 0.05), while the expression of TLR22 was increased (P < 0.05). After the Vibrio parahaemolyticus challenge test, ACP and AKP activities were increased in the G4 and G5 groups, while mortality was lower than in the G1 group (P < 0.05). GML significantly modulated the abundance of intestinal microbiota, with the G4 and G5 groups increasing the relative abundance of the Firmicutes and Bacillus, respectively (P < 0.05). The alpha diversity of the G5 group (Sob, Chao1 and ACE) was significantly higher than that of the G1 group (P < 0.05). In summary, the optimal level of GML was 1700 mg/kg according to the regression equation model fitted by the WGR index.

Modulation of growth performance, antioxidant capacity, non-specific immunity and disease resistance in largemouth bass (Micropterus salmoides) upon compound probiotic cultures inclusion

An 8-week feeding trial was conducted to evaluate the effects of dietary supplementation of compound probiotic cultures (CPC; Bacillus subtilis, Lactobacillus plantarum and Saccharomyces cerevisiae) on the growth performance, antioxidant capacity, non-specific immunity and disease resistance of juvenile largemouth bass. Triplicate groups of largemouth bass (average weight 42.05 ± 0.02 g), with a destiny of 30 individuals per tank, were fed diets supplemented with different concentration of compound probiotic cultures (CPC) (0%, CPC (0.0); 0.5%, CPC (0.5); 1.0%, CPC (1.0); 2.0%, CPC (2.0)). After the feeding trial, tissue samples of largemouth bass were collected and the challenge test with Aeromonas hydrophila was performed. Results indicated that the CPC supplementation produced no significant difference on the growth performance, feed utilization and body composition of largemouth bass, while significantly increased the cumulative survival rate in the Aeromonas hydrophila challenge test. Meanwhile, the inclusion of CPC elevated the hepatic antioxidant capacity, and the highest activity of antioxidant enzymes, including T-AOC, CAT, GPx and T-SOD, was observed in the CPC (2.0) group. Meanwhile, the transcription of Nrf2/keap1 and antioxidant related genes, including CAT, GPx, GST, SOD1 and SOD2, was significantly elevated with the inclusion of CPC. In addition, the inclusion of CPC improved the non-specific immunity of largemouth bass. The activity of serum lysozyme was significantly elevated in the CPC (2.0) group, while the transcription of RelA and pro-inflammatory factors, including TNF-α and IL-1β, was inhibited with the inclusion of CPC. Meanwhile, related genes potentially linked to RelA, including TLR2 and p38 MAPK, were detected that their relative expression was significantly inhibited with the inclusion of CPC. The current findings indicated that the inclusion of 2% CPC improved the antioxidant capacity, non-specific immunity and disease resistance of juvenile largemouth bass, and suggested that 2% CPC as a functional additive could be applied to the diet of juvenile largemouth bass in aquaculture practice.

The Effect of Dietary Saccharomyces cerevisiae on Growth Performance, Oxidative Status, and Immune Response of Sea Bream (Sparus aurata)

The objective of this study was to evaluate the beneficial effect of Saccharomyces cerevisiae (SC) on growth, intestinal morphometric characteristics, blood indices, redox balance, expression of immune-related genes, and their involvement in disease resistance in sea bream (Sparus aurata). Three hundred healthy sea bream fingerlings were allocated into equal four groups (15 fish per hapa). The first group was served as a control and received a basal diet, while the other three groups were fed diets containing 1, 2, and 4 g/kg diet SC, respectively. At the end of week 16, the daily weight gain, specific growth rate, and feed utilization were significantly higher in the SC2 and SC4 groups than the control (p < 0.05). SC dose-dependently improved intestinal morphology, and the 4 g/kg diet significantly increased dry matter, crude fat, and crude protein percentage of body composition when compared with the control group. The 4 g/kg SC boosted innate immune response and phagocytic activity, and all SC-supplemented diets improved total protein, glucose, triglycerides, and urea concentrations, as well as intestinal digestive enzymatic activities. All estimated oxidative markers were significantly enhanced in the group that received 4 g/kg SC when compared with the control and other SC groups (p < 0.05). Feeding the fish a diet supplemented with 4 g/kg SC markedly regulated the expression of HSP70, IGF1, and IL-1β genes. In addition, the 4 g/kg SC-supplemented diet was the most effective in protecting the fish against Vibrio parahaemolyticus challenge. In conclusion, SC-enriched diet improved growth performance, intestinal morphology, redox homeostasis, and immune response of S. aurata with the 4 g/kg concentration as the most effective.

Effects of Dietary Phaffia rhodozyma Astaxanthin on Growth Performance, Carotenoid Analysis, Biochemical and Immune-Physiological Parameters, Intestinal Microbiota, and Disease Resistance in Penaeus monodon

The present study aimed to investigate the effect of dietary astaxanthin (Ast) from Phaffia rhodozyma on growth performance, survival, carotenoid content, the activity of antioxidant and immune-related enzymes, intestinal microbiota comparison, and disease resistance against Vibrio parahaemolyticus in Penaeus monodon. Juveniles (average weight 3.15 ± 0.12 g) were fed with six experimental diets supplemented with 0 (Control), 20.5, 41, 61.5, 82, and 102.5 mg/kg of Ast (defined as diet A–D) in triplicate for 56 days. The results indicated that shrimp fed with Ast supplementation significantly (p < 0.05) improved growth performance compared with the control. Furthermore, significantly (p < 0.05) increased survival and decreased feed conversion ratio (FCR) demonstrated the beneficial effects of dietary Ast on enhancing nutrient utilization and ultimately improving the growth and survival of shrimp. Furthermore, shrimp fed with Ast including diet developed a deeper red color than the control, consistent with the significantly (p < 0.05) increased Ast deposition in the shrimp shell. Hemolymph-immunological parameters [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (AKP)] and hepatopancreatic antioxidant status [total antioxidant capacity (T-AOC), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD)] were significantly (p < 0.05) affected by dietary Ast supplementation. Dietary increasing Ast levels significantly (p < 0.05) increased shrimp resistance performance to V. parahaemolyticus according to the LT₅₀ results in the current study, which may be caused by increased total carotenoid contents in shrimp tissues from all the Ast-supplemented treatments. Conversely, intestinal microbiota biodiversity and richness were not affected by dietary Ast. The best performances of growth, antioxidant status, immunological response, and carotenoid deposition were observed in diets E and F among all the Ast-supplemented treatments. Overall, all the data suggested that dietary P. rhodozyma Ast played a critical role in improving growth performance, achieving the desired coloration, increasing carotenoid content, and keeping better health status of shrimp. Based on these positive performances, P. rhodozyma Ast could gain the trust of the consumers as a natural source and provide a potential alternative for synthetic Ast using in the Penaeus monodon culture industry.

Effects of Dietary Saccharomyces cerevisiae YFI-SC2 on the Growth Performance, Intestinal Morphology, Immune Parameters, Intestinal Microbiota, and Disease Resistance of Crayfish (Procambarus clarkia)

The present study aimed to evaluate the effect of the dietary supplementation of Saccharomyces cerevisiae YFI-SC2 on the growth performance, intestinal morphology, immune parameters, intestinal microbiota, and disease resistance of crayfish (Procambarus clarkia). Crayfish were randomly assigned to six different boxes and two different groups in triplicate. The control group received a basal diet and the treatment group received a diet containing S. cerevisiae at 10⁷ CFU/g. After feeding for 28 days, crayfish of the treatment group exhibited a significantly better weight gain ratio (WGR) and a specific growth rate (SGR) (p < 0.05) than crayfish of the control group. Compared to the treatment group, the control group intestines showed an oedema connective tissue layer and a weak muscle layer. For immune-related genes, Crustin2 expression was similar between the groups, whereas Lysozyme and prophenoloxidase from treatment group expression levels were upregulated significantly (p < 0.05) after 14 and 28 days of feeding. Prophenoloxidase showed the highest expression, with 10.5- and 8.2-fold higher expression than in the control group at 14 and 28 days, respectively. The intestinal microbiota community structure was markedly different between the two groups. After 14 and 28 days of feeding, the relative abundance of Cetobacterium and Lactobacillus increased, whereas Citrobacter and Bacteroides decreased in the treatment group compared with that of the control group. The challenge test showed that crayfish of the treatment group had a significantly enhanced resistance against Citrobacter freundii (p < 0.05). Our results suggest that a S. cerevisiae-containing diet positively influenced the health status, immune parameters, intestinal microbiota composition, and disease resistance of crayfish.

Dietary Supplementation of Yeast Culture Into Pelleted Total Mixed Rations Improves the Growth Performance of Fattening Lambs

There is a growing interest in the use of yeast (Saccharomyces cerevisiae) culture (YC) for the enhancement of growth performance and general animal health. Grain-based pelleted total mixed rations (TMR) are emerging in intensive sheep farming systems, but it is uncertain if the process of pelleting results in YC becoming ineffective. This study aimed to examine the effects of YC supplemented to pelleted TMR at two proportions of corn in the diet on animal performance, feed digestion, blood parameters, rumen fermentation, and microbial community in fattening lambs. A 2 × 2 factorial design was adopted with two experimental factors and two levels in each factor, resulting in four treatments: (1) low proportion of corn in the diet (LC; 350 g corn/kg diet) without YC, (2) LC with YC (5 g/kg diet), (3) high proportion of corn in the diet (HC; 600 g corn/kg diet) without YC, and (4) HC with YC. Fifty-six 3-month-old male F2 hybrids of thin-tailed sheep and Northeast fine-wool sheep with a liveweight of 19.9 ± 2.7 kg were randomly assigned to the four treatment groups with an equal number of animals in each group. The results showed that live yeast cells could not survive during pelleting, and thus, any biological effects of the YC were the result of feeding dead yeast and the metabolites of yeast fermentation rather than live yeast cells. The supplementation of YC resulted in 31.1 g/day more average daily gain regardless of the proportion of corn in the diet with unchanged feed intake during the 56-day growth measurement period. The digestibility of neutral detergent fibre and acid detergent fibre was increased, but the digestibility of dry matter, organic matter, and crude protein was not affected by YC. The supplementation of YC altered the rumen bacterial population and species, but the most abundant phyla Bacteroidetes, Firmicutes, and Proteobacteria remained unchanged. This study indicates that YC products can be supplemented to pelleted TMR for improved lamb growth performance, although live yeast cells are inactive after pelleting. The improved performance could be attributed to improved fibre digestibility.

Proteomic analysis of individual giant freshwater prawn, Macrobrachium rosenbergii, growth retardants

"Iron prawn" is a condition of severe growth retardation that fishers call. The giant river prawn (Macrobrachium rosenbergii) is a commercially important species contains high protein content and functional nutrients. However, no proteomic information is available for this species. We performed the shotgun 2DLC-MS/MS proteomic analysis of the total protein from "iron prawn". Total 19,758 peptides corresponding to 2613 high-confidence proteins were identified. These proteins range in size from 40 to 70 kDa. KEGG analysis revealed that the largest group consisting total 102 KEGG pathway proteins comparing the "iron prawn" with the normal prawn. Additionally, 7, 11, 1, 6, and 5 commercially important enzymes were found in the eyestalk, liver, muscle, ovary, and testis, respectively. The functions of these differently expressed enzymes include immune system action against pathogens, muscle contraction, digestive system metabolism, cell differentiation, migration, and apoptosis in the severe growth retardation of "iron prawn". Our work provides insight into the understanding of the formation mechanism of "iron prawn".

Effects of reducing dietary fishmeal with yeast supplementations on Litopenaeus vannamei growth, immune response and disease resistance against Vibrio harveyi

The aim of this experiment was to investigate the effects of reducing dietary fishmeal (FM) with yeast culture (SYC) supplementation on growth, immune response, intestinal microbiota, intestinal morphology, and disease resistance of Litopenaeus vannamei. A total of 480 shrimps with an average initial body weight of 0.35 ± 0.002 g were randomly distributed into twelve tanks. Three isonitrogenous (40.00 crude protein) and isolipidic (8.00 crude lipids) diets with yeast culture supplementing fishmeal were formulated. The groups were divided into two (2) namely control group and experimental groups. The formulations of the groups were control (0 %, without yeast culture) and the experiment groups (SYC) [(1 % of yeast culture), and (2 % of yeast culture)]. Each diet was delivered in four replicate per treatment group. The results indicate significant improvement on the growth indices (specific growth rate, weight gain rate, survival rate and lower feed conversion ratio) with yeast culture treatment group after 56 days feeding trials (P < 0.05). Total hemolymph protein, superoxide dismutase, catalase, alkaline phosphatase, acid phosphatase, lysozyme and phenoxidase were enhanced but low aspartate aminotransferase, alanine aminotransferase, and glucose were observed in shrimp fed yeast culture diets (P < 0.05). The SYC groups showed insignificant differences in hemolymph cholesterol and triglyceride. Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant bacteria found in all the SYC groups. At the genus level, Vibrio was significantly decreased (P < 0.05) in 2 % yeast culture diets supplemented group whereas the beneficial bacteria Pseudoalteromonas was significantly enhanced. Moreover, intestinal villus length and width in shrimps fed yeast culture diets were improved (P < 0.05). Dietary yeast culture supplementation can improve growth, intestinal health, immune response, and resistance against Vibrio harveyi infections in L. vannamei.