Volume 72, 2020

Permanent URI for this collection

Browse

Recent Submissions

Now showing 1 - 10 of 48
  • Item
    Effect of salinity on growth performance and resistance of the clam Cyclina sinensis against Vibrio parahaemolyticus infection
    ( 2021) Ni, Qian ; Li, Wenqian ; Jia, Xuewen ; Dong, Zhiguo ; Ge, Hongxing
    We examined the growth performance, immune parameters and the susceptibility to Vibrio parahaemolyticus in the clam Cyclina sinensis, which had been reared at different salinity levels of 10‰, 20‰ and 30‰ for 60 days. At the end of the feeding experiment, the biggest shell length and body weight was found in 20‰, followed by 30‰ and 10‰. No significant differences in superoxide dismutase (SOD) activity were observed among the clams held in 10‰, 20‰ and 30‰. Na+/K+ -ATPase (NKA) activity of the clams held in 20‰ and 30‰ were significantly lower than that in group 10‰. The lowest activities of lysozyme (LZM) and glutamic-pyruvic transaminase (GPT) were found in group 10‰. The Integrated Biomarker Response index (IBR) values of the clams had an inverse relationship with salinity: 11.28, 3.40 and 2.85 in 10‰, 20‰ and 30‰, respectively. At the end of the feeding experiment, the clams were infected with V. parahaemolyticus. As time after infection goes on, the survival rate of clams reared in 20‰ was not significantly different with the other two treatments from 24 to 48h after infection. However, from 72 to 120h after infection, it was significantly lower than those reared in 10‰, while it was significantly higher than those reared in 30‰. It is concluded that the clam C. sinensis reared in 10‰ seawater may reduce growth performance and immune ability, whereas increase resistance against V. parahaemolyticus infection.
  • Item
    Dietary lipid levels requirements of hybrid yellow catfish (Pelteobagrus fulvidraco × P. vachelli
    ( 2021) Mamuru, Gobeng L.S. ; Qiang, Jun ; Tao, Yi-Fan ; Chen, De-Ju ; Bao, Jing-Wen ; Ngoepe, Tlou K. ; Zhu, Hao-Jun ; Li, Hong-Xia ; Xu, Pao
    A 12-week feeding trial was conducted to determine the dietary lipid levels requirements of hybrid yellow catfish using pelleted diets containing six different lipid levels formulated to contain graded levels of 0.0% (control), 3.4%, 6.8%, 10.2%, 13.6%, and 17% of dry matter. A total of 504 juveniles with an average initial body weight of 8.77±0.012 g were randomly divided into 6 groups containing 3 triplicates with 28 fish per tank and fed each of the experimental diets. Results showed that maximal final body weight, weight gained and specific growth rate were significantly higher in the groups fed 3.4%, 6.8%, and 10.2% compared with that of groups fed 13.6% and 17.0% (P < 0.05). Feed conversion ratio and protein efficiency ratio were significantly lowered in the 6.8% and 10.2% groups (P < 0.05). The hepatosomatic index had no significant difference (P > 0.05) while the viscerosomatic index significantly decreased in 6.8% and 10.2% groups. White blood cells, red blood cells, hematocrit and platelets levels significantly increased in the decreased dietary lipids levels (P < 0.05) while hemoglobin had no observed significant difference (P > 0.05). Serum alanine aminotransferase, aspartate transaminase, total protein, total cholesterol, triglyceride and glucose were significantly influenced by the dietary lipid levels. Liver superoxide dismutase and catalase concentration decreased significantly in the 6.8% and 10.2% groups. Malondialdehyde increased in 6.8% and 10.2% groups. Glutathione peroxide showed insignificant results (P > 0.05). Study results suggested that, dietary lipid levels containing 3.4%,6.8% and 10.2% significantly influenced growth, blood function, antioxidant status and strengthened immune response in hybrid yellow catfish while higher dietary lipid levels (13.6% and 17.0%) decreased body weight and weakened immunity.
  • Item
    Aeromonas veronii, a potential pathogen of enteritis in snakehead fish Ophiocephalus argus
    ( 2020) Wang, Huicong ; Gu, Ying ; Luo, Guilan ; Cao, Haipeng
    Enteritis is known as a major disease in snakehead fish Ophiocephalus argus aquaculture and has resulted in large economic losses. Yet only scarce information is available on Aeromonas veronii as a causal agent for enteritis in O. argus. In this study, a virulent strain, temporarily named HY2, was isolated from diseased snakehead fish suffering from enteritis, and was identified as A. veronii through molecular and phenotypic methods. In addition, the HY2 isolate showed an LD50 value of 2.8×105 CFU mL-1, and was highly sensitive to aminoglycosides, macrolides, polypeptides, quinolones, sulfonamides and tetracyclines antibiotics. To the best of our knowledge, this is the first report of A. veronii as a potential pathogen of enteritis in snakehead fish.
  • Item
    Effects of dietary P:E ratio and Rhizoclonium in two stocking densities on growth and profitability of Nile tilapia in intensive pond culture
    ( 2020) Jumah, Yashier U. ; Tumbokon, Barry L.M. ; Serrano Jr, Augusto E.
    Two onsite tests were carried out to determine the effects of varying dietary protein to energy (P:E) ratio in intensive culture of Nile tilapia in two different places at two stocking densities. In both field trials, three diets were used namely commercial (CM) diet, control (CO) diet containing no Rhizoclonium and a diet containing Rhizoclonium replacing 52% of soybean meal (RLP); the diets contained decreasing P:E ratio of 21, 16 and 12 gMJ-1, respectively. The first trial was conducted in Aklan, Philippines at a stocking density of 17 fishm-2 while the second was in Pangasinan, Philippines at 27 fishm-2. In both trials, the three diets were fed for 2 months to 3 replicate cages of Nile tilapia, all of which were randomly placed in about 1.0 ha fresh water fish pond. In the first trial in Aklan, at 17 fish m-2 stocking density, no significant differences in the parameters were observed except in the absolute growth rate (AGR) in which the RLP dietary treatment exhibited a higher value than did either the CM or the CO diet. In Pangasinan, at 27 fish m-2 stocking density, significant differences in TFI, DFI and SGR were observed, all the other parameters were statistically similar. The RLP group exhibited lower total feed intake (TFI) and daily feed intake (DFI) but higher specific growth rate (SGR) than did either the CM or CO diet. In either stocking densities, feed cost was the main determinant of profitability in which the RLP group resulted in significantly highest profitability i.e., lowest total production cost, highest gross income and highest profit and profit margin. Although profit was significantly higher in the higher stocking density, profit margin was significantly higher in the lower stocking density. There was no statistical interaction between dietary treatment and stocking density as analyzed by two-way analysis of variance.
  • Item
    The secondary bacterial infection caused by WSSV outbreaks impacts shrimp Marsupenaeus japonicus’ growth as well as its intestinal microbiota’s composition and function
    ( 2020) He, Zihao ; Zhao, Jichen ; Liao, Xuzheng ; Chen, Xieyan ; Fu, Zhibin ; Sun, Chengbo ; Ni, Zuotao
    Intestinal microbiota homeostasis is a complex ecosystem and is essential for promoting aquatic animals’ growth. Invading pathogens can cause dynamical composition and structure change in the hosts’ microbiota due to this affecting their functions. WSSV is one of the most common and dangerous shrimp pathogens, which leads to white spot disease with too high mortality. A few studies on shrimp intestinal microbiota mainly focused on the changes during acute infection stage. Marsupenaeus japonicus is one of the most cultured shrimp with a decent ability to cope with environmental changes. In the current research, using M. japonicus as a model, we compared the differences of intestinal microbiota between healthy shrimp and the shrimp that survived through the WSSV outbreak. Our study showed that compared to the healthy M. japonicus, the WSSV outbreak disrupted intestinal microbiota structure in the survived shrimp: There was less potential beneficial bacteria and more harmful bacteria. Furthermore, the diversity and total abundance of intestinal microbiota in WSSV-survived shrimp increased significantly. On top of that, a metagenomic analysis by PICRUSt suggested that the changed intestinal microbiota could help the host to combat the secondary bacterial infections caused by WSSV outbreaks by regulating cell growth and death, reducing cell motility, improving energy metabolism, and increasing intestinal enzyme activities regardless the smaller sizes of WSSV-survived shrimp. This could be a result of excessive energy consumption and reduced nutrient-absorbing intestinal microbiota. Our study indicated that shrimp intestinal microbiota plays a fundamental role in combating against secondary infections and regulating the hosts’ growth post WSSV outbreaks. The eventual goal is to development of more efficient diagnostics and therapeutic strategies.
  • Item
    Effects of feeding strategies on growth,body composition, intestine digestive enzymes activities and intestine histology of Megalobrama pellegrini (Tchang, 1930) early juveniles raised in flow-through system
    ( 2020) Qu, Huantoao ; Chen, Lei ; Yang, Jinyuan ; Liao, Jianxin ; Wei, Dai ; Lu, Xuebao
    To determine the effects of feeding rate and feeding frequency on growth performance, digestive enzymes activities, and intestine development of Megalobrama pellegrini in a replicated flow-through system, we conducted a 42-day experiment. We designed three feeding rates (5%, 6.5%, and 8% body weight/day, BW/d) and two feeding frequencies (2 and 3 meals/day; m/d) in this experiment. Fish (0.57 ± 0.01 g) were distributed into 18 tanks with 70 individuals and fed with a commercial diet (33% crude protein, 4% total lipid). Results showed that the highest weight gain was found in the fish fed diet with 6.5% BW/day and 3 m/d, which was significantly higher in comparison with that of other feeding rate groups (5% BW/d and 6.5% BW/d) at both feeding frequency (2 and 3 m/d). Fish growth performance was significantly affected by the feeding rate but not by the feeding frequency. The significantly higher feed conversion ratio (FCR) was recorded at 8% BW/d with 3 m/d than other treatments. Furthermore, fish fed diet at 8% BW/d with 2 m/d had significantly high mortality during the middle of this trial. In contrast, we found that other fish groups' survival rates were higher (over 90%), and there were no significant differences among them. We saw a significantly lower whole-body crude protein, lipid, and intestinal digestive enzymes in fish fed at a ratio of 8% BW/d with 3 m/d compared with other treatments. Moreover, our findings revealed intestinal villi fusion and exfoliation in this group compared with other treatments. In conclusion, the Megalobrama pellegrini received a feeding rate of 6.5% BW/d, and a feeding frequency of 2 m/d may be the optimum feeding regime for raising Megalobrama pellegrini in a flow-through system.
  • Item
    Effects of Dietary Wheat Gluten Meal on Growth, Intestinal Morphology, and Microbiome in Juvenile Large Yellow croaker Larimichthys crocea
    ( 2020) Fan, X.J. ; Yin, H. ; Chai, R.Y. ; Shui, X.M. ; Huang, J. ; Wang, P.
    Wheat gluten meal (WGM) was evaluated as a replacement for fish meal (FM) for juvenile Larimichthys crocea.FM was replaced by 0%, 25%, 50%, 75%, and 100% of WGM (WGM0, WGM25, WGM50, WGM75, and WGM100, respectively). In addition, all diets except the control group were supplemented with amino acids. Fish were fed twice daily for 56 days. There were no significant differences in survival and feed conversion ratio (FCR) among all treatments (P>0.05). WGM25, WGM50, and WGM75 groups had significantly higher specific growth rate (SGR) and weight gain ratio (WGR) than those fed with WGM0 (P<0.05). There were no significant differences in mucosal thickness (MT), lamina propria width (LW), mucosal fold height (MH), and goblet cell quantity of single hair (GC) for all the diets (P>0.05). The indexes of Chao1, Shannon, Simpson, and Good coverage in fish fed with WGM0, WGM50, and WGM100 were not significantly affected (P>0.05). Firmicutes (81.03~94.03%) were the dominant bacterial community in juvenile large yellow croaker. Compared with the WGM0 group, the abundance of Firmicutes increased significantly, and Proteobacteria decreased significantly in the WGM100 group (P<0.05). These results suggested that WGM could replace 366.3 g kg-1 FM of the juvenile large yellow croaker diet.
  • Item
    Effects of Dietary Lipid Levels on Growth Performance, Whole Body Composition and Digestive Enzyme Activity of Juvenile Bighead Carp (Aristichthys nobilis)
    ( 2020) Cai, Fangfang ; Wang, Yan ; Hu, Xiangin ; Huang, Feng ; Wang, Fucheng ; Liu, Hongming
    A 60-day study was conducted to investigate the effects of dietary lipid levels on growth, whole body composition and digestive enzyme activity of bighead carp (Aristichthys nobilis) with initial average weight (3.28 ± 0.11) g. Six isonitrogenous (40.25% crude protein) diets were formulated to contain graded contents of lipid (4.72%, 7.31%, 11.02%, 14.90%, 17.14%, and 19.37%) using corn oil and soybean oil as main lipid source. The results showed that the maximum weight gain (WG) and specific growth rate (SGR) were recorded at 11.02% dietary lipid level. Significant alterations were demonstrated on whole-body composition by different dietary lipid levels. Crude lipid content of whole body increased in parallel with the increase of dietary lipid levels. Fish fed diet with 11.02% lipid level showed lowest moisture and ash content. The activities of amylase and protease initially increased before decreasing, and the highest activities of amylase and protease were obtained in individuals fed the 11.02% lipid content diet. There were no significant differences in condition factor (CF) and hepatosomatic index (HSI) (P >0.05). Based on the polynomial regression analysis of WG and SGR, this study suggested that the optimum dietary lipid requirement of juvenile bighead carp was estimated to be 7.77%~8.31%.
  • Item
    Effects of dietary P:E ratio and Rhizoclonium in two stocking densities on growth and profitability of Nile tilapia in intensive pond culture
    ( 2020) Serrano Jr, Augusto E. ; Tumbokon, Barry L.M. ; Abalos, Rosie S. ; de la Pena, Raul ; Bohulano, Nenia N. ; Binh, Mac N.
    Two onsite tests were carried out to determine the effects of varying dietary protein to energy (P:E) ratio in intensive culture of Nile tilapia in two different places at two stocking densities. In both field trials, three diets were used namely commercial (CM) diet, control (CO) diet containing no Rhizoclonium and a diet containing Rhizoclonium replacing 52% of soybean meal (RLP); the diets contained decreasing P:E ratio of 21, 16 and 12 gMJ-1, respectively. The first trial was conducted in Aklan, Philippines at a stocking density of 17 fishm-2 while the second was in Pangasinan, Philippines at 27 fishm-2. In both trials, the three diets were fed for 2 months to 3 replicate cages of Nile tilapia, all of which were randomly placed in about 1.0 ha fresh water fish pond. In the first trial in Aklan, at 17 fish m-2 stocking density, no significant differences in the parameters were observed except in the absolute growth rate (AGR) in which the RLP dietary treatment exhibited a higher value than did either the CM or the CO diet. In Pangasinan, at 27 fish m-2 stocking density, significant differences in TFI, DFI and SGR were observed, all the other parameters were statistically similar. The RLP group exhibited lower total feed intake (TFI) and daily feed intake (DFI) but higher specific growth rate (SGR) than did either the CM or CO diet. In either stocking densities, feed cost was the main determinant of profitability in which the RLP group resulted in significantly highest profitability i.e., lowest total production cost, highest gross income and highest profit and profit margin. Although profit was significantly higher in the higher stocking density, profit margin was significantly higher in the lower stocking density. There was no statistical interaction between dietary treatment and stocking density as analyzed by two-way analysis of variance.
  • Item
    The use of otolith shape to identify stocks of Konosirus punctatus
    ( 2020) Li, Songzhang ; Wang, Xianwen ; Wang, Haixia ; Wu, Chunzhi ; Zhan, Huixiang ; Su, Shengqi ; Gao, Tianxiang ; He, Tao
    Konosirus punctatus is an important economic fish in the Northwest Pacific Ocean, especially along the coast of China, and an important substitute in the marine ecosystem. The aim of this study is to quantify the variation of sagittal shapes to discriminate the K. punctatus stocks between China coasts (Wei Hai, Yan Tai, Zhou Shan, Wen Zhou, Dong Ying, Hai Kou and Qing Dao) and Aomori (Am) in Japan by comparing the sagittal morphometric features. The sagitta variation of eight K. punctatus stocks was examined using nine shape indices (Roundness, Circularity, Form-factor, Rectangularity, Ellipticity, Radius ratio, Feret ratio, Aspect ratio and Surface density). Multiple comparisons on shape indices showed that three shape indices (Roundness, Feret ratio and Surface density) have significant differences between nine stocks. The comprehensive judgment accuracy rate is 54.5%. Based on the Fourier coefficient eight Fourier parameters can fit the shape of sagittal. The comprehensive judgment accuracy rate is 56.1%. The results showed that the otolith morphology was not significantly different between seven China stocks, while the China stocks showed a large sagittal morphological difference from the Japanese stock. It could be related to environmental factors and geographical conditions in various sea areas.