Volume 71, 2019

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https://hdl.handle.net/10524/61063

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Molecular Cloning, mRNA Expression, and Nutritional Regulation of a Fatty Acyl Δ6-Desaturase-like Gene of the Manchurian Trout, Brachymystax lenok (Pallas)
(2019) Jian-hua Y; Shu-guo L; Hua-xin N; Jie C; Zong-fu H; Ying H
The fatty acyl delta-6 desaturase (Δ6-desaturase) is a key rate-limiting enzyme in the biosynthesis of long-chain polyunsaturated fatty acids (LCPUFAs). To study the effects of different oil sources in the feed on the nutritional regulation of Δ6-desaturase-like gene mRNA expression, the fulllength cDNA of the Δ6-desaturase-like gene was cloned from the liver of Manchurian trout (Brachymystax lenok). A 9-week feeding trial was performed, and the fish received diets with three different oil sources: fish oil (FO), sunflower oil (SO), and linseed oil (LO). The results showed that the 2448 bp long full-length cDNA contained an open reading frame (with a length of 1365 bp), encoding 454 amino acids. Gene expression analysis indicated that Δ6-desaturase-like gene mRNA is widely distributed throughout different tissues, with highest expression levels in both the liver and the brain. The linolenic acid (ALA) and linoleic acid (LA) compositions were highest in LO and SO diets, respectively. The eicosapentaenoic acid and docosahexaenoioc acid composition in LO and SO diets were significantly lower than in the FO diet. Fish fed with SO and LO showed significantly higher liver expression levels of Δ6-desaturase-like gene mRNA than those fed with FO. This indicates that SO and LO in the diet affected the nutritional regulation of the Δ6-desaturase-like gene mRNA in the liver of the Manchurian trout. In addition, these data suggest that the Manchurian trout has the ability to synthesize long-chain unsaturated fatty acids (LC-PUFAs) from ALA and LA.
Withdrawal Period of Oxolinic Acid in Cobia (Rachycentron canadum): Validation of an LC-MS/MS Method
(2019) Chen RS; Sheu SY; Xue YJ; Wang CY; Liu CH; Kuo TF; Wang JH; Chou CH
Oxolinic acid (OXO) has been routinely used in aquaculture as both prophylactic and chemotherapeutic agents, principally against systemic bacterial infections. The residue depletion of OXO was investigated in cobia following multiple (5 days) in-feed dosing (30 and 60 mg/kg body weight/day) at 25°C; we assessed OXO concentrations of liver and muscle (+skin) samples post-treatment for three weeks. The OXO residues were quantified using a validated ultra-high-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS) method and the results indicated recoveries of 86.6-95.8%, with relative standard deviations (RSD) less than 8.5% for intra- and inter-day precisions. Within the range of 10−500 ng/g, the calibration curves for all matrices presented a determination coefficient greater than 0.99. Limit of detection and quantification were estimated at 6 and 10 ng/g, respectively. In order to account for the high variability of the residue data, a safety span corresponding to 50% of depletion time could be seen as appropriate. Considering a maximum residue limit (MRL) of 50 ng/g established by the Taiwan FDA for OXO in muscle with skin in natural proportions, a withdrawal period of 15 days was calculated for the sum of 10day depletion time and 5-day safety span. These results revealed that the analytical method is developed for residue OXO and that the withdrawal period is appropriate.
Expression Response Profiles of Toll-Like Receptor Family Members in Cyprinus Carpio after Lipopolysaccharide Stimulation, and Implication for Disease Control in Aquaculture
(2019) Lin B; Chen L; Zhang J; Zhang X; Wang H; Li G; Wang Q; Deng J
In this study, response profiles of 17 Toll-like receptors (TLRs) to lipopolysaccharide (LPS) stimulation were studied at mRNA levels in the liver of the common carp Cyprinus carpio. Three types of gene response profiles were observed in TLR family. The first pattern was that the expressions of some TLRs were initially up-regulated and then decreased with time. This finding indicated that the responses of these TLRs were sensitive to LPS stimulation, and it was suggested that these TLRs were involved in responding and coping with LPS, implying that these TLRs were important in immune defense from Gram-negative bacteria. The second pattern was that some TLR expressions showed no obvious change after LPS stimulation, demonstrating that they were not sensitive to LPS and probably did not recognize LPS, implying that these TLRs should not be regarded as the major receptors to be regulated to prevent disease caused by Gram-negative bacteria. The third pattern was that gene expressions of partial TLRs were significantly downregulated after a period of LPS stimulation, indicating that their gene expressions were inhibited by LPS action, and implying that these TLRs did not initiate the signal pathway for inflammation reaction to clear Gramnegative bacteria. This study is based on the different response patterns of TLRs to LPS, that imply that the sensitive response TLR genes to LPS might be selected as target genes regulated by drugs that control inflammation reaction of diseased fish in aquaculture.
Nitrite-Induced Oxidative Stress, Histopathology, and Transcriptome Changes in the Mud Crab (Scylla paramamosain)
(2019) Cheng C-H; Su Y-L; Ma H-L; Deng Y-Q; Feng J; Chen X-L; Guo Z-X
Nitrite in the aquatic environment is highly toxic to aquatic animals. However, the mechanism by which the mud crab responds to nitrite-induced stress remains unclear. In this study, we investigated the physiological response and molecular mechanism in the mud crab (Scylla paramamosain) exposed to the acute nitrite exposure (20 mg/L) for 24h. The results showed that nitrite exposure induced significant changes in antioxidant enzyme activity and MDA content. Severe cytological damage was observed in the hepatopancreas. After 24h exposure to nitrite, 11,638 differentially expressed genes (DEGs) were identified by transcriptome analysis. These DEGs were involved in many pathways related to oxidative stress and immune responses. Our results also found that FoxO signaling pathway, p53 signaling pathway, and NF-kB signaling pathway participated in the anti-stress defense against nitrite stress. The study provides new insight into the understanding of nitrite-induced toxicity in the mud crab.
Effect of Dietary Iron Levels on Tissues, Intestinal Digestive Enzyme Activity, and Muscle Nutrient Compositions of Juvenile Bighead Carp (Aristichthys nobilis)
(2019) Feng W; Hu X; Wang F; Huang F; Liu L; Li H; Liu H; Yang W
A 60-day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on iron concentration in tissues, intestinal digestive enzyme activities, and muscle nutrient composition of bighead carp (Aristichthys nobilis). Six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diets) using ferrous sulfate (FeSO4) as the source. When Fe dietary content increased to 43.1 mg/kg, trypsin activity in the intestine significantly increased and thereafter decreased. Lipase and amylase activity in the intestine significantly increased with increasing dietary Fe levels up to 123.3 mg/kg diet and thereafter decreased. With lipase and amylase activity in the intestine as the main indicators, Fe content of 123.3 mg/kg was the most suitable dietary Fe level for A. nobilis. Crude protein content in the muscle of the 84.2 mg/kg Fe group was the highest in all groups. Results indicated that the appropriate levels of dietary Fe alter muscle nutrient composition of A. nobilis. Fe content in the muscle and vertebrae significantly increased with increasing dietary Fe levels up to 203.1 mg/kg diet. Fe contents in different tissues were as follows: Vertebra >intestine >muscle.
Differences in Total Carotenoid Content in Tissues of the Pearl Oyster Pinctada fucata with Regard to Cuticle Shell Color
(2019) Wei H; Chen M; Deng Z; Li Y; Ma Z; Wang Y
The aim of this study was to compare total carotenoid content (TCC) in tissues, and its correlation with shell color between four different shell color strains of Pinctada fucata. A total of 120 individuals (30 golden shells, 30 red shells, 30 black shell and 30 white shells) of P. fucata of similar size were evaluated. In this study, stomach, gill, adductor, and mantle were used for measuring the determination of TCC. The color measurements were taken from both the nacre shells and cuticle shells. The results showed that TCC varies significantly among four different tissues and the four different shell color strains (P < 0.05). A significant difference between the cuticle shell colors of the four different shell color strains of P. fucata was observed (P < 0.05), while the nacre shell colors of four shell strains were similar (P > 0.05). In the present study, results indicated that the TCC of P. fucata was significantly related to tissue and cuticle shell colors (P < 0.001), but not related to nacre shell colors (P > 0.05). TCC relating to the cuticle shell color suggested that increasing or decreasing TCC in P. fucata through selective breeding of cuticle shell color was feasible, and it could be significant both for food for humans, and the cultivation of high-quality pearls.
Inhibitory Effects of Galla chinensis, Tannic Acid, and Gallic Acid on Saprolegnia parasitica
(2019) Zhang QQ; Li AH; Liu LH
The inhibitory effects of Galla chinensis and its two main ingredients, tannic acid and gallic acid, on Saprolegnia parasitica were examined, using the method of agar plate assay and liquid dilution assay. The results showed that all the three tested drugs had different degrees of inhibitory activity on mycelial growth and zoospore germination of Saprolegnia parasitica, with tannic acid showing the most significant inhibition. The mycelial growth of S. parasitica was completely inhibited by tannic acid at the concentration of more than 32 mg/L, and the germination rate of S. parasitica zoospores decreased by 66% at a concentration of 5 mg/L. Considering the low cost of tannic acid together with its inhibitory effect on S. parasitica, tannic acid showed the most significant potential in the prevention and control of fish saprolegniasis.
Discontinuous Administration of β-glucan is Effective for Preventing Immune Fatigue in Litopenaeus vannamei
(2019) Luo Z; Guo J; Hao S; Zhang Z; Tang H; Wu H; Jiang J; Ye G; Feng S; Bai X
β-glucan is an effective, available immunostimulant that has been successfully used to improve the immune defense of shrimp against pathogenic infection. However, the long-term continuous use of β-glucan can lead to immune fatigue, and intermittent feeding may be an effective way of avoiding this phenomenon. A 60-day growth trial was conducted to compare the effects of different feeding strategies of diets containing 200 mg/kg β-glucan on the growth and immune system of the Pacific white shrimp Litopenaeus vannamei. The results showed that either continuous feeding or intermittent feeding of diets containing 200 mg/kg β-glucan did not promote the growth of L. vannamei. However, the levels of superoxide dismutase, alkaline phosphatase, and acid phosphatase in the hepatopancreas of L. vannamei in the intermittent feeding group were significantly higher than those in the control and continuous feeding groups. Expression levels of the genes encoding LPS/β-glucan binding protein, superoxide dismutase, lysozyme, penaeid in-3a, and catalase were also significantly upregulated in the intermittent feeding group, whereas most of the immune parameters in the continuous feeding group were not significantly different from those of the control group. After artificial infection with Vibrio parahaemolyticus, the average mortality rates in the control group, the continuous feeding group, and the intermittent feeding group were 76.67%, 78.89%, and 45.56%, respectively. The results indicated that the addition of 200 mg/kg β-glucan to the diet did not promote the growth of L. vannamei, but the strategy of intermittent feeding effectively prevented immune fatigue and enhanced disease resistance, perhaps by increasing nonspecific immunity in L. vannamei.
Streptococcal Infection Caused by Enterococcus casseliflavus in Cultured Meagre (Argyrosomus regius)
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Urku C; Timur G
Gram Positive Streptococci (GPS) have become increasingly important fish pathogens. In this study, 170 moribund marine fish (sea bass, gilthead sea bream, meagre, sharp snout sea bream, and marine rainbow trout), obtained from 30 fish farms in the Black Sea and Aegean Sea regions of Turkey, were investigated for the presence of GPS. Streptococci were recovered from fifteen moribund young meagre (Argyrosomus regius) from an inland fish farm located in the Aegean region. The isolates were identified as Enterococcus casseliflavus using a Polymerase Chain Reaction-based (PCR) method. This result was confirmed with 16S rRNA gene sequencing and serological methods, including slide agglutination and IFAT. The diseased meagre showed unilateral or bilateral exophthalmia, loss of eyes, and hemorrhagic ulcerative skin lesions on the body surface. Histopathologically, tubular degeneration and congestion in the kidney, myopathy in the heart tissue, discharge of the white pulp in the spleen, extensive vacuolation of hepatocytes, and congestion in the liver were observed. Intraperitoneal challenge with one of the isolates in healthy European sea bass (Dicentrarchus labrax) in resulted mortalities 8 days post-injection.
Effect of Ammonia Exposure on the Non-Specific Immunity of Fresh Water Pearl Mussel Hyriopsis cumingii
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Xia H; Yang P; Liu L; Luo Y; Sun Y; Wang W; Yuan M; Liu W
Ammonia-N, the principal end-product of protein catabolism, is an important environmental toxic factor in ponds. Elevated environmental ammonia-N is very toxic to aquatic animals and has a deleterious effect on their immune system. However, its effect on their immune system remains unclear. In this study, the effects of ammonia-N (0, 5, 10 and 30 mg/L) on immune responses of Fresh Water Pearl Mussel Hyriopsis cumingii were determined. When exposed to 5 mg/L ammonia-N lysozyme activity increased significantly. Superoxide dismutase activity was highest in the 5 mg/L group followed by the 10 mg/L group. The marked decrease of Lysozyme activity of Fresh Water Pearl Mussel Hyriopsis cumingii in 10 mg/L and 30 mg/L ammonia-N groups suggests that the higher concentrations of ammonia-N reduces or inhibits their non-specific immunity. Compared to the control group, superoxide dismutase activity in 30 mg/L ammonia also decreased significantly. When exposed to 5mg/L ammonia-N, catalase, acid phosphatase and alkaline phosphatase activity enhanced. In the 10 mg/L and 30 mg/L group, ammonia-N decreased significantly The lysozyme, catalase, acid phosphatase and alkaline phosphatase activity showed a similar tendency. This suggests that in H. cumingii immunostimulatory response is enhanced at low ammoniaN concentrations. The results of this study provide a theoretical basis for disease prevention in the freshwater pearl mussel.
Effects of Fish Meal Replaced by Maggot Culture on Growth Performance, Body Composition, and Antioxidant Responses of Hybrid Tilapia (Oreochromis niloticus × O. aureus)
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Qiao Y; Mai K; Ai Q
This present study was conducted to evaluate the effects of replacing fish meal with maggot culture, on growth performance, body composition, and antioxidant enzyme activity in hybrid tilapia (Oreochromis niloticus × O. aureus). Five isonitrogenous and isoenergetic diets were formulated to contain graded levels of maggot culture (0%, 1%, 2%, 4% and 5%), which replaced 0% (the control), 20%, 40%, 80% and 100% fish meal, respectively. Each diet was randomly fed to triplicate groups of 30 hybrid tilapia (initial mean body weight: 2.12 ± 0.01g) per tank for 8 weeks. Fish were fed to satiation twice daily (08:00 and 16:00). Results showed that the inclusion of maggot culture did not significantly influence survival, weight gain, feed conversion rate, and morphological parameters of tilapia. Catalase and superoxide dismutase activity were not significantly affected by the supplementation of maggot culture. Also, the inclusion of maggot culture did not significantly influence moisture, protein, lipid, and ash contents of whole body and muscle. Based on these above observations, fish meal could be totally replaced by maggot culture without a negative influence on growth performance, body composition, and antioxidant capability in hybrid tilapia.
Effects of Different Salinities on Growth, Body Composition, Oxygen Consumption Rate, and Ammonia Excretion Rate in American shad (Alosa sapidissima) Juveniles
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Shui C; Yan Y; Shi Y; Xu J; Deng P
A laboratory experiment was undertaken to analyze the effects of salinity on growth, body composition, oxygen consumption, and ammonia excretion of anadromous American shad (Alosa sapidissima) juveniles. Results showed the best survival rate occurred at 5‰ and 15‰. The relative weight gain and the specific growth rate declined as salinity increased. However, feed conversion rate increased with increasing salinity. Oxygen consumption rates showed a parabolic relationship in relation to salinity. From the quadratic relationship (y= -0.0004x2+0.0166x+0.319; R2=0.801; P<0.05), the highest oxygen consumption rate occurred at a salinity of 20.75‰. The ammonia excretion ratio decreased significantly as salinity increased from 10‰ to 15‰. No further differences were observed in salinities ranging from 15‰ to 40‰. There were no significant influences of salinity on whole body protein and moisture content. Lipid content declined as salinity increased. Results indicate that an appropriate increase in salinity was beneficial to the culture of American shad juveniles. The optimal salinity for American shad juveniles ranged from 15‰ to 20‰.
Effects of High Carbohydrate and Benfotiamine on the Growth and Feed Efficiency of Juvenile Nile Tilapia, Oreochromis niloticus
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Lauzon QD; Canillo SDT; Tumbokon BL; Serrano AE Jr.
This study aimed to evaluate the effects of a high carbohydrate diet (HC) alone and HC supplemented with benfotiamine (HCB), a human anti-diabetic supplement, on the growth performance of Nile tilapia fry, Oreochromis niloticus. A total of 180 Nile tilapia fry (AWB=0.01g) were randomly distributed to 9 tanks and fed one of three experimental diets, namely, a control diet containing 15% carbohydrate; high carbohydrate diet (HC) containing 25% carbohydrate; and high carbohydrate diet (25%) supplemented with 0.02% benfotiamine (HCB) for 8 weeks. Increasing corn starch in the diet from 15% (i.e. control diet) to 25% (i.e. HC diet) did not have any effect on the growth performance nor feed efficiency of the Nile tilapia. In contrast, Nile tilapia fed the HCB diet exhibited significantly the highest final average body weight, weight gain, specific growth rate, feed intake and whole-body lipid content and the most efficient FCR among the treatments. Results of the attractability tests showed that the HCB diet significantly attracted the most percentage of fish. In conclusion, the findings indicated that the Nile tilapia efficiently utilized an increase of carbohydrate from 15% to 25% and that dietary benfotiamine significantly increased the utilization of this diet, enhancing further its growth performance and feed utilization; benfotiamine also increased the attractability of the diet.
Advances in Intestinal Mucosal Immunoglobulins of Teleost Fish (Review)
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Xia H; Yang P; Liu L.; Luo Y; Sun Y; Wang W; Chen N; Zhao J
Immunoglobulins are globulins with antibody activity or antibody-like structures, and fish were the first vertebrates to develop immunoglobulins. There are three major types of immunoglobulins (IgM, IgD and IgZ) in teleost fish, which play an important role in resisting pathogen infection. For fish, the intestinal tract is not only the place for nutrient digestion but also the largest endocrine organ. The intestinal mucosal barrier system can block pathogenic microorganisms and toxins and is important for immunologic defense. Therefore, the study of the molecular mechanism of fish immunoglobulin in intestinal mucosa is of great significance to the selection of immune prevention strategies for fish diseases. At present, information on the immune system of intestinal mucosa in fish is scarce, and there are still many problems in the function of newly identified antibodies, which need further research. In this study, we have summarized current knowledge about the types, gene structure, biological function, and immune response of immunoglobulins in teleost fish, and intestinal mucosal immune tissue of fish. The scientific questions in this field were also presented according to the progress from the latest research in fish immunology. The aim of present study is to provide a theoretical basis for the study of fish immunology.
Depletion Study of Oxolinic Acid in Freshwater Softshell Turtle (Pelodiscus sinensis) with Multiple-Dose Oral Administration
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Chen R.S; Sheu S.Y; Xue Y.J; Wang C.Y; Wang W.S; Wang J.H; Kuo T.F.; Chou C.H.
All drugs used in aquaculture must be approved by the government agency responsible for veterinary medicine; prudent use of antibiotics under veterinary supervision is critical in ensuring safety of aquaculture products. The international production of farmed turtle, considered a cultured aquatic species, has been growing continuously but control of bacteria proliferation in turtle farms requires frequent use of antimicrobials. In the present investigation, the residue depletion and withdrawal period of quinolone antibacterial oxolinic acid (OXO) was evaluated in Chinese softshell turtle Pelodiscus sinensis, after repeated (once daily for 5 days) oral doses of medicated feed containing OXO, at the dose of 30 and 60 mg/kg body weight (bw). Muscle and liver tissues were collected at 1, 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, and 48 days posttreatment, and OXO was quantified using a validated high-performance liquid chromatography with diode array detector (HPLC-DAD) method. According to the test preparation record, the limit of detection (LOD) and limit of quantification (LOQ) for OXO were estimated at 0.03 and 0.1 µg/g, respectively. Considering a maximum residue level (MRL) of 0.1 µg/g for OXO in muscle in European Union (EU) legislative framework, the longest withdrawal period of 72 days was calculated on the basis of a safety span (corresponding to 50% of the time point when at which residues fall below the MRL) added to the depletion time (48 days). These results may be helpful not only for the establishment of public policies regarding the use of OXO for turtle farming but also to producers for proper handling to ensure safe consumption.
Effects of Dietary β-glucan Supplementation on Growth, Innate Immune, and Capacity Against Pathogen Streptococcus iniae of Juvenile Pompano (Trachinotus ovatus)
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Do-Huu, H.; Nguyen, T.N.H.; Tran, V.H
This study investigated the effect of dietary β-glucan on growth, immunity, and resistance against Streptococci in pompano T. ovatus. Pompano were fed a control diet, and diets which included 0.10% or 0.20% of β-glucan. After being fed the diets for 3-weeks, growth rate, survival, blood parameters, and immunity were examined, and the fish were challenged with Steptococcus aniae for 10 days. At the end of the feeding trial, RBC, WBC, WBC:RBC ratio, and lymphocytes significantly increased (P ≤ 0.032), while monocytes significantly decreased (P ≤ 0.007) in fish fed 0.10-0.20% of β-glucan. Moreover, lysozyme was significantly higher (P ≤ 0.003) in fish fed β-glucan, while the phagocytic ratio was only significantly higher (P = 0.037) in fish fed 0.10% β-glucan. Furthermore, fish fed 0.10-0.20% β-glucan showed higher protection against S. iniae (P ≤ 0.002). Thus, a diet of β-glucan is recommended to improve non-specific immunity, growth in T. ovatus, and also to limit the adverse effects of S. aniae disease in this species.
The Effect of Dehulling and Extrusion of Jackfruit Artocarpus heterophyllus Seeds on Digestibility and Antinutrients, in Tilapia (Oreochromis niloticus) Diets
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Díaz-Vázquez IE; Zavala-Leal OI; Pacheco-Vega JM; Cuevas-Rodríguez BL; Ruiz-Velazco JM; Gutiérrez-Dorado R; Cordero-Ramírez JD
In the present study, the effect of dehulling and extrusion of Jackfruit seeds Artocarpus heterophyllus, and apparent digestibility of dry matter and protein was evaluated in feeds for Nile tilapia Oreochromis niloticus. For the digestibility bioassay, organisms with an average weight of 12.6 ± 3.1 g were used. The evaluation of the digestibility coefficient in vivo was determined by using the indirect method of chromium oxide as a marker. The dehulled Jackfruit seeds caused a significant increase in protein and lipids, and a significant decrease in fiber and ash respectively. The extrusion process did not significantly affect protein, fiber, ash, and carbohydrate content of the extruded flour, but caused a significant decrease in the lipid content of Jackfruit seeds. The results indicate that the extrusion process caused a significant decrease in the content of phytic acid, tannins, trypsin inhibitors, and saponins. In relation to trypsin inhibitors, dehulling did not have a significant effect. On the other hand, the combination of the extrusion and dehulling process allowed a significant decrease of phytic acid and tannins, while the dehulled of seeds did not have a significant effect on the phytic acid content. The combination of the dehulled and extrusion process caused a significant decrease in trypsin inhibitors and saponins with respect to raw Jackfruit seeds. The combination of the extrusion and dehulling process caused a significant increase in ADM of diets prepared with 30% of Jackfruit flours. The combination of the process of extrusion and dehulling of Jackfruit seeds allowed a significant increase in ADP compared to the unprocessed seeds. We conclude that dehulled and extruded Jackfruit flours represent a potential low cost, highly available alternative to replace fishmeal in the production of food for tilapia Oreochromis niloticus.
Characteristics of Communities in the Extracts of Different Purple Soils in the Sichuan Basin, China
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) He T; Chen X; Jiang R; Li Y; Li T; Su S
Pond soils play a fundamental role determining nutrient availability and regulate the characteristics of phytoplankton communities. This study investigated the change of phytoplankton communities in three types (alkaline, neutral, and acid) of purple soil. There were 107 species of phytoplankton detected in three purple soils belonging to 52 genera of 6 phyla (68 species in acid group, 69 species in neutral group and 64 species in alkaline group). The highest percentage of phytoplankton in three purple soil groups is Chlorophyta, followed by Bacillariophyta, and Euglenophyta. There were 23 species of 5 phyla in three purple soil ponds as the dominant species of phytoplankton, and the dominance varied from 0.05 to 0.67. The dominant species in neutral and alkaline purple soil groups were more than those in acid purple soil. Phytoplankton density varied from 43 to 7360 × 106 ind/L in the acid purple soil group, and the ratio of the highest value to the lowest one was 170. The variation range of phytoplankton density in neutral and alkaline purple soil ponds was 83 to 565 × 106 and 56 to 437 × 106 ind/L, and the ratio of the highest value to the lowest one was 6.8 and 7.8 respectively. The variation of biodiversity indices (Shannon—Wiener index, Pielous evenness index and Margalef richness index), were higher in the acid purple soil group than in the neutral and alkaline purple soil groups, similar to the result of phytoplankton density. Our results indicate that the phytoplankton community was more stable in the neutral and alkaline purple soil groups than in the acid soil group, and these two soil types are recommended for site-selection to build aquaculture ponds.
The Effect of Diet on Ovarian Development and Nutritional Tissue Composition of Portunus trituberculatus
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Hou W; Liu M; Wu X
This study investigated the effects of feeding trash fish (TF), formulated diet (FD), and mixed diets (MD) on ovarian development, fattening performance, and nutritional quality of P. trituberculatus. Formulated diet treatment resulted in lower gonadosomatic index, hepatosomatic index, meat yield, and total edible yield than the other treatments. It also showed lower protein (7.88%), lipid, and ash content in hepatopancreas and muscle, compared to the other treatments. Different diets significantly affected the contents of C16:0, C18:1n9, C18:2n6, C18:3n3 and C20:5n3 of hepatopancreas. FD treatment resulted in lower essential amino acids and non-essential amino acid contents in the muscle compared to TF and MD treatments. The highest and the lowest essential amino acids scores were found in the TF and FD treatments, respectively. In conclusion, these results indicated that FD is not suitable and requires further development for sub-adult crabs, while MD would be the recommended for fattening female P. trituberculatus.
Dietary Iron Requirements of Adult GIFT Tilapia (Oreochromis niloticus)
(The Israeli Journal of Aquaculture - Bamidgeh, 2019) Cheng X; Tian J; Yao Y; Jiang M; Liu W; Wu F; Yu L J; Lu X; Gao W; Wen H
Dietary iron requirement of adult Nile tilapia (Oreochromis niloticus), genetically improved farmed tilapia (GIFT strain), was determined in this study through a 77 day feeding trial. Diets with six concentrations of iron (45.55 - the control group, 94.91, 193.62, 292.34, 391.05, and 489.77 mg iron/kg diet) from ferrous sulfate were formulated and hand-fed to adult GIFT (initial body weight 174.58±3.49g). The results indicated that no fish died in all groups. Weight gain ratio, feed efficiency rate, as well as specific growth rate decreased in relation to increasing dietary iron levels, and reached the lowest when supplemented with 489.77 mg iron/kg diet. Crude body fat content showed an increasing trend in relation to increasing dietary iron levels. The iron content in the body, vertebrae, and liver significantly increased with dietary iron levels which reached up to 391.05 mg iron/kg diet. The number of red blood cells, the hemoglobin content and the packed cell volume was highest in 94.91 mg iron/kg group. In conclusion, dietary iron made no obvious improvement on growth performance, but improved hematopoietic function of adult Nile tilapia, reared in freshwater. We found that no additional iron needs to be added to the adult Nile tilapia (174.6–558.1 g) feed based on the growth, whereas broken-line regression analysis were used to determine the optimum iron requirements for maximum hemoglobin levels, the dietary iron requirement for hemoglobin was 120.94 mg iron/kg diet with ferrous sulfate as a source of iron.

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