Volume 74, 2022

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https://hdl.handle.net/10524/65093

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    The effect of Artemia nauplii (Artemia franciscana) enriched with different commercial products on the growth performance of the larvae of freshwater angelfish, Pterophyllum scalare (Lichtenstein, 1823)
    (2022) Özdoğan, Hasan B.E.
    The present study was planned to determine an optimum live-feeding protocol for angelfish larvae (Pterophyllum scalare). Larvae with an initial weight of 0.10 mg, a length of 4.5 mm, and a depth of 1 mm were reared on three different feeding regimens for 30 days. All experimental larval groups were fed Artemia nauplii from the end of the yolk-sac resorption. The control treatment (Group I) was maintained on Artemia nauplii on days 14-28, and on Artemia nauplii + dry feed on days 29 and 30. Group II was reared with Artemia nauplii enriched with Algamac 3050 on days 14-28 and with dry feed + Artemia nauplii enriched with Algamac 3050 on days 29 and 30, whereas Group III was fed with Artemia nauplii enriched with Red Pepper on days 14-28, and with dry food + Artemia nauplii enriched with Red Pepper on days 29 and 30. The highest weight (37.8±0.51 mg) and length (15.8±0.35 mm) were determined in Group II with significant differences from the control group (p<0.05). However, enrichment treatments were comparable in terms of growth performance (p>0.05). The survival rate of the larvae in the treatments varied between 70-75% without significant differences (p>0.05). Overall, the study results suggest that a feeding protocol for angelfish larvae with the administration of Artemia nauplii during the first two weeks after hatching and then enriched Artemia with Algamac 3050 over the following 14-28 days followed by a gradual weaning onto dry feed.
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    Transcriptome analysis reveals the molecular basis of the response to acute hypoxic stress in blood clam Scapharca broughtonii
    (2022) Wang, Zhenyuan; Zhang, Gaowei; Ge, Guangyu; Wu, Lina; Wang, Yan; Liu, Zhihong; Zhou, Liqing; Sun, Xiujun; Wu, Biao
    Hypoxia tolerance and adaptive regulation are important for aquatic animals, especially for species with poor mobility, such as most bivalves. Previous studies have confirmed that the blood clam Scapharca broughtonii has strong hypoxia resistance. However, the molecular mechanism supporting its hypoxic tolerance is still largely limited. To further screen the genes and their potential regulation of hypoxia tolerance, the transcriptome changes of S. broughtonii after acute hypoxic stress were explored by RNA sequencing. In this study, the average value of Q30 is 92.89%, indicating that the quality of sequencing is relatively high. The Unigenes obtained were annotated using four databases, namely Interpo, KEGG, Swisspro and TrEMBL. The annotation rates in these four databases were 71.82%, 75.95%, 92.98%, and 79.26%, respectively. And also, there were 649 DEGs in group B (dissolved oxygen (DO) of 2.5 mg/L) compared with group D (DO of 7.5 mg/L), among which 252 were up-regulated, and 397 were down-regulated. There were 965 DEGs in group A (DO of 0.5 mg/L), 2.5 mg/L, and 7.5 mg/L, compared with group B, among which 530 were up-regulated, and 435 were down-regulated. Meanwhile, there were 2,040 DEGs in group A compared with group D, among which 901 were up-regulated, and 1,139 were down-regulated. The main metabolic-related pathways of KEGG enriched in this study included Insulin secretion, Insulin signaling pathway, MAPK signal transduction pathway, and PPAR signaling pathway. These pathways may be critical metabolic pathways to solve energy demand and rebuild energy balance in S. broughtonii under hypoxic conditions. This study preliminarily clarified the response of S. broughtonii to hypoxia stress on the molecular levels, providing a reference for the following study on the response laws of related genes and pathways under environmental stress of S. broughtonii.
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    Effect of Vitamin B Complex and Phosphorus on Stress Resistance and Phosphorus Uptake in Barramundi
    (2022) Yani, Ahmad; Karim, Muhammad Y.; Zainuddin, Zainuddin; Aslamyah, Siti
    Barramundi, the Asian sea bass (Lates calcarifer Bloch 1790), is a valuable aquaculture commodity, but seed survival is generally low. This study used a completely randomized design (two factors; 16 treatments; 3 replicates) to examine the effect of adding vitamin B complex and phosphorus to the rearing media on the survival, stress resistance, and phosphorus content of barramundi larvae. Barramundi larvae aged two days were stocked at a density of 25 fish L-1 in 40 L green plastic basins (30 L water) and reared for 30 days with natural feed (Chlorella and rotifers). The factor I was vitamin B complex with 4 levels: 0, 75, 150, and 225 mg L-1. Factor II was phosphorus with four levels: 0, 0.5, 1.0, and 1.5 mg L-1. Commercially available B vitamin complex and phosphorus mineral supplements were dissolved in water and added to the larval-rearing media. Analysis of variance showed that the combination of vitamin B complex and phosphorus treatments had a significant effect (P < 0.01) on survival, stress resistance, and phosphorus uptake. Survival and phosphorus content in barramundi larvae were highest with a combination of 150 mg L-1 vitamin B complex and 1.0 mg L-1 phosphorus and lowest in control (0 mg L-1 of both additives).
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    Hematological parameters of red tilapia (Oreochromis sp.) fed lemongrass essential oil (Cymbopogon citratus) after challenge with Streptococcus agalactiae
    (2022) Thuong, Huyen N.T.; Tran, Thi-Lan-Nhi; Le, Thi-Nhu-Trang; Vo, Van-Thanh
    The study involved feeding lemongrass essential oil (LEO) supplements to red tilapia (Oreochromis sp.) at concentrations including Control - 0 mg, T1 – 200 mg, T2 – 300 mg, and T3 – 400 mg per kg of feed. The research investigated changes in hematological (HCT, Hb, RBC, WBC & thrombocytes) and erythrocyte’s morphological (major/minor axis; perimeter, and area of erythrocyte) parameters before infection, 5- and 10-days post-infection (DPI). According to analytical findings, a diet containing LEO enhanced the synthesis of both erythrocytes and leukocytes in the peripheral blood of red tilapia after 20 days of being used. Therefore, the indicators of this group of fish showed better performance than those that did not use LEO supplement five days after bacterial infection. Fish fed 200 mg/kg of LEO after being challenged with S. agalactiae for ten days showed an improved effect on red blood cell production. White blood cells decreased at all concentrations because of citral’s immunomodulatory properties.
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    Preliminary screening, identification and biological characteristic analysis of Bacillus probiotics isolated from Cynoglossus semilaevis
    (2022) Gao, Zhao; Zhang, Yonggang; Wang, Qinglin; Ren, Hai; Gao, Guisheng; Jin, Xiaomin; Fang, Hai
    To screen local probiotic strains to promote antibiotic-free farming, two potential probiotic strains (S3, S5) were recognized among 89 cultivable bacterial strains isolated from the intestine of healthy Cynoglossus semilaevis. The two potential probiotic isolates were analyzed in terms of their morphology, physiology, biochemistry, the similarity of 16S rDNA sequences, growth characteristics, enzyme production capacity, bacterial antagonism, and safety in C. semilaevis. The results revealed that the bacterial morphology and physiological and biochemical characteristics of S3 and S5 were similar to those of Bacillus subtilis. The 16S rDNA sequences had 99.9 % similarity to that of Bacillus subtilis MH 145363.1. Therefore, S3 and S5 were identified as B. subtilis. In addition, we found that S3 and S5 had a strong ability to secrete amylase, protease, and lipase. During the safety tests of S3 and S5 in C. semilaevis with high concentrations, C. semilaevis in immersion, injection, and feeding groups remained in good condition without falling ill or dying. Moreover, we found that S3 and S5 exhibited superior growth at 25~50℃, salinities of 10 to 40, and pH values of 5 to 9. Furthermore, S3 and S5 had significant bacteriostatic activity against Vibrio anguillarum, Aeromonas salmonicida, and Shewanella algae, which are the main pathogenic bacteria of mariculture fish. In summary, S3 and S5 showed superb inhibition of the pathogenic bacteria of marine fish, rapid growth, eurythermal and euryhaline features, and suitability for the intestinal environment of C. semilaevis. Thus, strains S3 and S5 have excellent commercial development potential. These results provide a basis for ecological disease prevention strategies and are also valuable for developing and utilizing probiotics.
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    Transcriptome response of pubertal male Clarias macrocephalus to dietary 17α-methyltestosterone
    (2022) Serrano, Augusto E.; Bautista, Lemark M.; Deallo, Apple G.; Tumbokon, Barry L. M.; Ariñez, July B.
    We studied the mechanism of the effects of 17α-methyltestosterone (MT) on previously reported enhanced growth and maturation of the Asian catfish Clarias macrocephalus. A total of 18 pubertal male (3 fish·tank-1) catfish (ABW=125.97 g) were stocked into six experimental circular tanks and fed with a basal diet (control) or a basal diet containing 60 mg MT kg-1 diet for 90 days. At the termination of the experiment, livers were excised, and total RNA was extracted, evaluated, and reverse transcribed to cDNA. Six libraries of cDNA (3 for the control and 3 for the MT-treated group) were subjected to bioinformatics. Differentially expressed genes (DEGs) were identified using similarity scores of the de novo assembled transcript with those in the seven public databases. There were 141 up- and 72 down-regulated DEGs, mostly belonging to uncharacterized/not yet identified proteins. Thus, DEGs in the top enriched KEGG pathways were used to characterize the effects of MT. Upregulated DEGs included tyrosine hydroxylase (TH), Cytoplasmic Polyadenylation Element Binding (CPEB), Fas-associated death domain (FADD), Major Histocompatibility Complex class 1 (MHC-1), other immune-related genes, among others. Down-regulated DEGs included Cytochrome P450 family one subfamily A member 1 (CYP1A1), Alternative oxidase (AOX), UDP-glycosyltransferase (UGT), Acyl-CoA Synthase Bubblegum Family Member 1 (ACSBG), Stearoyl-CoA Desaturase (SCD), among others. In conclusion, MT-treated male Clarias macrocephalus exhibited up-regulation of pathways protecting cellular conditions like cell proliferation, survival, development and homeostasis processes, for development and homeostasis processes. MT also affected changes in bile acid production and the inhibition of the production/conversion of testosterone. MT resulted in the down-regulation of a serotonergic system that possibly affected gonadal development, inhibition of the retinoid enzyme that would otherwise diminish the full effects of MT or its metabolite, and inhibition of the formation of estrogen, leading to down-regulation of several estrogen-related KEGG pathways. The results provide valuable information about the key genes for use as biomarkers of maturation and reproduction for the Asian catfish and contribute to our understanding of the molecular mechanisms and regulative pathways behind these two processes in fish.
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    Effects of Glyphosate-Resistant Genetically Modified Soybean on Blood Biochemical Indexes, Hepatopancreatic Antioxidant Capacity and Tissue Morphology of Cyprinus carpio
    (2022) Zhang, Jiaguo; Yu, Taotao; Huang, Xiaoxia; Ma, Qianqian; Zhang, Changfeng; Zhou, Qunlan
    The juvenile carps (Cyprinus carpio) were fed diets with four protein sources (15% and 30% glyphosate-resistant genetically modified (GM) named GM 15 and GM 30, respectively, and 15% and 30% non-genetically modified (NGM) soybean named NGM 15 and NGM 30) for 180 days. Results showed that alkaline phosphatase (ALP) activity for the GM30 group was significantly lower than that of the NGM30 group. The activity of glutathione peroxidase (GSH-Px) in the hepatopancreas of carp for the GM30 group was significantly higher than that of the NGM15 group (P<0.05). And the content of malondialdehyde (MDA) for the GM30 group was higher than that of the NGM30 group during the whole culturing process (P<0.05). The activity of catalase (CAT) for the GM30 group was significantly lower than that of the NGM30 group during 60 days and 180 days (P<0.05). While no significant differences were observed in the growth indexes, organ indexes, and muscle nutritional components of carp among the four groups (P>0.05). This study indicates that it may aggravate the damage degree of intestinal epithelial cells of carp and more easily cause liver cell damage in the short term when the amount of GM soybean in the feeds was 30%. Therefore, higher glyphosate-resistant GM soybean may have adverse effects on the carp's serum, intestinal, and hepatopancreas and considerably reduce the hepatopancreatic carp's antioxidant capacity.
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    Antibacterial characterization of Bacillus velezensis LG37 and mining of genes related to biosynthesis of antibacterial substances
    (2022) Liu, Guangxin; Deng, Yiqin; cheng, Changhong; Ma, Hongling; Jiang, Jianjun; Feng, Juan; Guo, Zhixun
    Bacillus velezensis LG37 secretes various antibacterial substances and inhibits the growth of other bacteria. Here, we analyzed the antibacterial characteristics and the screening and verification of genes related to the synthesis of the antibacterial substance of LG37 by antibacterial activities experiment, Local BLAST+, and RT-PCR. LG37 was isolated from aquaculture water and preserved in our laboratory. The phylogenetic tree was used to analyze the genetic relationship between LG37 and the bacteriostatic test indicator strain. LG37 had a more substantial inhibitory effect on closely related strains, while the inhibitory effect on the more distantly related strains was weak. Combined with the results of genome sequencing, the ribosomal peptide (RP) bacteriocin gene and non-ribosomal peptide synthetase (NRPSs) related gene clusters were screened and analyzed. A total of six gene-coding RP bacteriocins and two genes coding surfactins and fengycin A NRPSs gene cluster were screened. Local BLAST+ analysis revealed a total of 11 NRPSs gene clusters. The active expression of the NRPSs and RP encoding genes was further validated by RT-PCR. The findings revealed various genes and gene clusters encoding RP bacteriocins and NRPSs in B. velezensis LG37. The bacterium is potentially valuable in diverse applications in aquaculture.
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    The evaluation of ammonia tolerance in introduced and local Pacific white shrimp, Litopenaeus vannamei, populations in China
    (2022) Wang, Jing; Liu, Jianyong
    The white shrimp, Litopenaeus vannamei, is one of the most valuable commodities in the global seafood trade. Affected by high-density farming environments, ammonia accumulates in shrimp cultures and has a strong toxic effect, resulting in poor shrimp survival and poor immune function and metabolism. We selected six different populations of L. vannamei from Xing Hai No.1 (A and B), CHAI, Sy Aqua, PRIMO, and a second-generation Sy Aqua-PRIMO hybrid population (SP). The shrimps (3.24 ± 0.71 cm body length) were exposed to ammonia (24 h, 48 h), followed by recovery (R48 h, R96 h) to assess the tolerance of different populations. The survival rate (SR), immune-related enzymes (superoxide dismutase SOD, catalase CAT, and Glutathione peroxidase GSH-PX), Malondialdehyde (MDA), and metabolism (glutamate dehydrogenase GDH, glutamine synthetase GS, and aspartic acid transaminase GOT) and were measured at different populations under acute ammonia stress. Multiple comparisons of the ammonia resistance index from six populations showed that the expression of these indicators varied among the populations. The degree of lipid peroxidation in the Sy Aqua and PRIMO was significantly higher than in the other populations (P < 0.05), and the ammonia metabolism index was poor. The GDH and GOT genes for the Xing Hai No.1 (A) were higher than for the other populations. Mortality and physiological indicators recovered to varying degrees for all experimental populations following 96 h of ammonia relief, whereas the Sy Aqua and PRIMO showed a noticeable lag. These results indicated that the immunity and metabolic capacity of Xing Hai No.1 (A) might be higher than those of Sy Aqua and PRIMO. These data could have value in developing future scientific breeding schemes and in the sustainability of shrimp farming.
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    Embryonic Development of Black Neon Tetra Hyphessobrycon herbertaxelrodi Géry, 1961
    (2022) Çelik, Pınar; Çelik, İhsan
    The current study described the embryonic development stages of black neon tetra (Hyphessobrycon herbertaxelrodi), an economic ornamental fish. We characterized the stages of the zygote, cleavage, blastula, gastrula, segmentation, pharyngula, and hatching occurring during embryogenesis, which emphasizes changing spectrum of the main development processes from fertilization to incubation. The findings were put forth and photographed by examining live embryos under microscopy. Embryonic development of black neon tetra concluded at 24 ± 0.5°C water temperature at 20-21 hours. The first embryonic division occurs within the first 43 minutes after fertilization, and the process goes on to blastula at 02 hours and 28 minutes. The gastrula stage began at 02.57 hours, while 6 somite segmentation stages were observed to occur at 08.14 hours. Following the pharyngula stage seen between 17 to 20 hours, the hatching occurred at 20-21hours. The results of this study can provide significant benefits to professional breeders in the aquaculture of black neon tetra and other ornamental fish species.
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    Effects of vitamin E on growth and maturation in the Asian catfish (Clarias macrocephalus) at puberty
    (2022) Serrano, Augusto E.; Bautista, Lemark M.; Tumbokon, Barry L.M.
    The maturation of male fish is a problematic aspect of Clarias macrocephalus and probably one of the causes of the population's disappearance in the usual places where they once abound. The present study aimed to explore feed additives to enhance its maturation from puberty. Vitamin E (VE) is essential in the reproduction of animals, including fish. A growth trial was conducted in which groups of C. macrocephalus were fed experimental diets containing graded levels of VE in the form of α-tocopheryl acetate (α-TA), namely, 0, 100, 200, 300 and 400 mg VE·kg-1 diet. After 90 days, growth and maturation were assessed, and reproductive performance was tested by conducting induced spawning and artificial fertilization. Results showed growth and nutrient utilization indices were better in groups fed diets containing VE than in the control group. Maturation indices such as GSI, gonad weight, lengths, egg diameter, and fecundity were enhanced in the VE-treated groups. Reproductive performance, such as fertilization, hatching, and larval survival rate, was enhanced in C. macrocephalus broodstock in VE-treated groups. Quantitative estimates for optimal VE dose that elicited maximal response values ranged from 202.1 to 230.0 mg VE·kg-1 diet.
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    Autophagy genes of ATG5-ATG12 complex in response to exogenous stimulations in Litopenaeus vannamei
    (2022) Yuan, Yunhao; Huang, Yongxiong; luo, Junliang; Jian, Jichang; Cai, Shuanghu; Yang, Shiping
    Autophagy plays an important role in resisting pathogens infection and environmental stress. However, there are few studies on autophagy and its regulation in Litopenaeus vannamei. In this study, the autophagy-related genes of ATG5-ATG12 complex (ATG5, ATG7, ATG10 and ATG12) were cloned and investigated on the response to exogenous stimulations in L. vannamei. Multiple sequence alignment and phylogenetic analysis of different species showed that four autophagy genes were conserved among different species. Tissue detection showed that the four autophagy genes were expressed in all tissues, and the expression level was the highest in the hepatopancreas in L. vannamei. Furthermore, the expression levels of the four autophagy genes were up-regulated significantly after stimulation with Vibrio harveyi and the virus analog poly(I:C) (p<0.05), and their peak values occurred at 24-48h. These results indicated that ATG5, ATG7, ATG10 and ATG12 may be involved in resisting pathogen infection in L.vannamei, which provided a basis for studying the molecular mechanism of autophagy in resistance to pathogen infection of L. vannamei.
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    Effects of salinity and alkalinity on growth and survival of all-male giant freshwater prawn (Macrobrachium rosenbergii De Man, 1879) juveniles
    (2022) Day, Pham V.; Huong, Huynh K.; Truc, Phan T.T.; Nhi, Nguyen T.H.; Toan, Diep T.; Son, Lai P.; Nam, Ho K.; Nguyen, Pham T.B.; Hieu, Phan C.; Diep, Doan X.; Mai, Le T.P.
    All-male giant freshwater prawns (AMGFPs) have been a popular crop cultivated in the Mekong Delta, Vietnam, due to their proven production efficiency compared to all-female or mixed-sex prawn cultures. However, the crucial water quality factors impacting AMGFP aquaculture efficiency have yet to be elaborately investigated. Two separate experiments were randomly arranged with three replicates to evaluate the effects of salinity or alkalinity on the growth and survival of AMGFP juveniles during the grow-out period. The results show that the prawn survival rate in the salinity range of 0–15‰ varied from 66.1 to 74.8％ and in a salinity range of 0–5‰ was relatively low compared to the range of 10-15‰; however, the difference was not significant among salinities after 90 days of culture (p > 0.05). All the prawn growth performance parameters significantly decreased with increasing salinities of 0, 5, 10, and 15‰ after 30, 60, and 90 days of culture (p < 0.05). Notably, the prawn yield did not significantly differ between salinities of 0 and 5‰ (p > 0.05), and both were significantly higher than those at salinities of 10 and 15‰ (p < 0.05) after 90 days of culture. In addition, the survival rate reached 82.5–84.4％ and did not significantly differ among alkalinities of 80, 100, 120, 140, and 160 mgCaCO3 L−1. However, the growth performance parameters and yield of AMGFPs at an alkalinity of 160 mg L−1 were significantly higher than those at lower alkalinities (80, 100, 120, and 140 mg CaCO3 L−1) after 90 days of culture. Therefore, it is recommended that a salinity range of 0–5‰ and alkalinity of 160 mgCaCO3 L−1 is optimal for the growth-out culture of AMGFP juveniles.
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    Analysis of intestinal flora and environmental microbial diversity of Takifugu rubripes
    (2022) Ma, Mingxing; Ye, Xuying; Zhang, Sai; Wang, Xiuli; Qiu, Xuemei
    Takifugu rubripes (T. rubripes) is marine fish rich in protein and essential amino acids. With the continuous development of T. rubripes farming, intensive aquaculture has increased the infection rate with fish diseases. To explore the relationship between environmental microbial communities and gut microbiota, we sequenced the 16s rRNA gene V3–V4 region of the microorganisms in the aquaculture water and gut flora of T. rubripes. The results indicated 934 operational taxonomic units for T. rubripes gut contents and aquaculture samples. A total of 31 phyla and 498 genera were identified. At the phylum level, except for the phylum Proteobacteria, the dominant phyla in intestinal contents were Firmicutes, Acidobacteria, and Fusobacteria. However, the dominant phyla in water were Actinobacteria, Cyanobacteria, and Patescibacteria. At the genus level, intestinal contents included Photobacterium, Arcobacter, Vibrio, and Ruminococcaceae. The water samples mainly included CladeIa, Rhodobacteraceae, Eutreptiella pomquetensis, Lentibacter, CladeIII, and PeM15. Principal component analysis showed that the microbial compositions of samples from the same source were similar. There were significant differences between the intestinal flora and water microorganisms. Therefore, the research results showed the differences between the microbial communities in the intestinal tract and aquaculture water of T. rubripes and the characteristics of the main pathogenic bacteria; this could help guide the environmental regulation and disease prevention of T. rubripes aquaculture.
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    Hepatopancreatic transcriptome response of Penaeus vannamei to dietary ulvan
    (2022) Serrano, Augusto E.; Tumbokon, Barry L.M.
    The study aimed to determine the effect of feeding dietary ulvan on some genes and pathways of Penaeus vannamei juveniles. Feeding a diet containing ulvan at 1.0 g·kg-1 resulted in differentially expressed genes (DEGs) between the treatments and the control group. Ulvan resulted in 53 DEGs with 26 up and 27-down-regulated DEGs. The DEGs were immune-related, while several affected the energy and substrate metabolic pathways. Specific genes upregulated were Glycerol-3-phosphate acyltransferase (GPAT) of the glycerolipid synthesis, centrosomal protein 120 involved in cell cycling and other activities, RNA helicase, an enzyme involved in opening up DNA molecules, ATP-binding cassette, TATA-binding protein, taurine transporter, transcriptional enhancer factor (TEF), C-type lectin among others. Down-regulated genes included gamma-crystallin, which acts as molecular chaperones; catenin alpha, which is involved in adhesion complex; dystrophin, which is involved in scaffolding for several signaling molecules; and maintenance muscle integrity, among others. Top DEGs that affected significantly important pathways include TEAD (transcriptional enhancer factor domain), GSK3B (glycogen synthase Kinase 3 beta), SLC6A1 (i.e., solute carrier Family 6 Member 1), and ADCY2, which affected signal transduction, environmental adaptation as well as the endocrine, immune, nervous, and digestive systems. In conclusion, dietary ulvan resulted in the up-regulation of immune-related DEGs, which could probably be used to adapt to unfavorable conditions and also affected some energy and substrate metabolic pathways that could potentially be used to direct the overall metabolism.
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    17α-Methyltestosterone enhances growth and reproductive performance of immature male Asian catfish (Clarias macrocephalus)
    (2022) Bautista, Lemark M.; Tumbokon, Barry L.M.; Serrano, Augusto E.
    This study aimed to assess the effects of 17α-methyltestosterone (MT) on the growth and reproductive performance of male Asian catfish (Clarias macrocephalus). A total of 36 immature male Asian catfish (ABW = 125.97 g) were randomly distributed into 12 circular tanks, and fed with either the control diet (with no MT) or diets containing MT at 60 mg·kg-1, 90 mg·kg-1, or 120 mg·kg-1 for 45 days. Results showed that weight gain (WG), specific growth rate (SGR) and feed intake (FI) were significantly higher in the male catfish fed with diets containing 60 and 90 mg·kg-1 MT than in those fed with the control diet. Also, the diet attractability test revealed that the 60 and 90 mg·kg-1 MT groups significantly attracted more catfish than did the control diet; however, increasing MT to 120 mg·kg-1 reduced its attractability to the immature male catfish. MT-treated male catfish exhibited significantly heavier and significantly longer testes than male catfish fed the control diet at the termination of the feeding trial. These male catfish also exhibited significantly higher gonadosomatic indices (GSI) than catfish in the control group. Following induced spawning of nontreated female catfish and artificial fertilization of its eggs using testis preparation from the experimental male catfish at the termination of the feeding trial, results showed that testis preparations from all MT-treated males resulted in significantly higher fertilization (FR) and hatching rates (HR) of the eggs. In conclusion, incorporating MT to the diet improved both the growth and reproductive performance of the male Clarias macrocephalus. Precisely, dosages of optimal dietary MT using a quadratic model for maximal SGR, GSI, FR, and HR values were estimated to be 58.3, 75.0, 90.6, and 78.2 mg·kg-1, respectively.
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    Industry-finance integration activities is beneficial to the improvement of business performance of fishery companies—Based on DEA-CCR Model and DEA-Malmquist Model
    (2022) Sun, Lanlan; Wang, Feifei; Zhao, Zhuming; Han, Xia; Chen, Jinhui; Jiang, Chingqing
    Fisheries are an essential component of the national economy. The evaluation of fishery enterprises' business performance helps reveal the fishery industry's operating efficiency and serve the fishery economy's sustainable and high-quality development. This study used the data of fishery companies with industry-finance integration on the stock market from 2012-2021 and conducted a comparative study on the business performance of fishery companies with industry-finance integration on the stock market based on the DEA-CCR model and DEA- Malmquist index method. Two main results were revealed (i) the integration of industry and finance was an effective means to improve business performance, and the financial gains from the integration of industry and finance by listed fishery companies improve the overall efficiency and total factor productivity (TFP) of enterprises. (ii) The average TFP of listed fishery companies in China is declining, and technological decline is the main reason for the decline in TFP.
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    Microbial-environmental interactions reveal the evaluation of fermentation time on the nutrient properties of soybean meal
    (2022) Jin, Baohu; Cai, Minglang; Wang, Aimin; Tian, Hongyan; Zhang, Wuxiao; Shao, Peng; Chen, Huangen; Liu, Xingguo; Zhu, Hao; Gu, Xizhang; Li, Hongqin; Liu, Cong; Wang, Xinsheng
    Microbial fermentation techniques are often used to improve their quality, where the keys are fermentation strains and fermentation time. This study studied the interaction between microbiota and environmental (or nutritional) factors and microbiota at different fermentation times to determine the most appropriate time, using lactic acid bacteria as fermentation strains. It can be concluded that fermentation improved the nutritional value of soybean meals. In the early stages of fermentation, debris in soybean meal highly proliferated and destabilized the microbial community, while pH and nutritional conditions played an important role in helping its stabilization. In addition, we must pay attention to the interspecific interactions of microorganisms, which makes it easy to understand how the microbial community maintains community stability. A 4-day fermentation of soybean meal with Lactobacillus is recommended.
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    Dietary calcium requirements of bighead carp (Aristichthys nobilis)
    (2022) Cao, Manxia; Gao, Pan; Wang, Fuchen; Huang, Feng; Wang, Yuanyuan; Hu, Xianqin; Wang, Wenbiao
    To investigate dietary calcium requirement of bighead carp (Aristichthys nobilis), six purified diets were formulated to contain different concentrations of calcium (0.09% (control), 0.43%, 0.76%, 1.12%, 1.44%, and 1.79% of dry diets). Each diet was hand-fed to triplicate 30 fish with an average initial body weight (3.31 ± 0.09 g) for 60 days. The results showed that weight gain (WG) and specific growth rate (SGR) significantly increased when dietary calcium level was from 0.09% to 0.76% (P < 0.05). The phosphorus and calcium contents of whole fish body were highest in the 0.76% and 1.12% group, respectively (P < 0.05). The serum phosphorus content in the 1.79% group was significantly lower than those in other groups (P < 0.05). As dietary calcium content was from 0.09% to 0.76%, the activities of lipase and proteinase in the intestine had a significant increase (P < 0.05), while the glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) activities were significantly decreased (P < 0.05). Based on quadratic curve model analysis with WG and WGR as the appraising criteria, the appropriate dietary requirement of calcium for the bighead carp larvae (3.31 ± 0.09 g) was 1.01% - 1.02%.
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    Transcriptome profiling of Penaeus vannamei hepatopancreas infected with WSSV following feeding diet containing ulvan
    (2022) Serrano, Augusto E.; Tumbokon, Barry L.M.
    The present study aimed to elucidate the mechanism of protection provided by dietary ulvan as observed in previous studies. Thirty shrimps (3.35 ± 0.08 g average body weight) were stocked in six polyethylene tanks (5 shrimps tank-1, treatments were in three replicate/tank) and were fed either a diet containing no ulvan (control) or containing ulvan at 1 g kg diet-1 for 35 days at 10% body weight twice daily. At the termination of the feeding, the shrimps were subjected to a white spot syndrome virus (WSSV) challenge test via intramuscular injection of the viral inoculum. Shrimps were sacrificed after 24 h of exposure, and the hepatopancreas was excised for total RNA extraction for transcriptome profiling. Biological validation of the RNA-seq results was also performed for 10 immune-related genes (6 up- and 4 down-regulated genes). A comparison of the ulvan group with the control group revealed that 69 differentially expressed genes (DEGs) were significantly up-regulated, whereas 640 were significantly down-regulated. 184 DEGs between the control and ulvan-treated groups were classified into six KEGG categories of Metabolism (145 DEGs), Organismal systems (16), Human disease (4), Genetic Information Processing (10), Cellular Processes (2), and Environmental Information Processing (7). The 145 DEGs under Metabolism were distributed to Level 2 subcategories as carbohydrate metabolism (59 DEGs), global and overview maps (44), energy metabolism (27), and amino acid metabolism (15). All candidate immune-related genes (67) were down-regulated except for 5 genes. The validation experiment showed proportionality of gene expressions of the qPCR and of those in the assembled transcriptome, justifying the acceptability of the RNA-seq results. In conclusion, data from the present study provided mechanisms for protecting the white shrimp by dietary ulvan against WSSV infection.