Growth performance,robustness against stress,serum insulin,IGF‐1 and GLUT4 gene expression of red tilapia (Oreochromis sp.) fed diet containing graded levels of creatine

The experimental diets containing five levels of creatine supplementation, namely control (N = 0 g/kg creatine), B1 (1.00 g/kg glycine), B2 (0.40 g/kg creatine), B3 (0.80 g/kg creatine) and B4 (1.20 g/kg creatine) were tested to red tilapia up to apparent satiation 3 times a day for 56 days. After the feeding trial, fish were stressed by air exposure for challenge test against stress. The results described that creatine supplementation improved final body weight, feed conversion ratio (FCR) and protein retention. Creatine supplementation decreased blood glucose, cholesterol and triglyceride levels (p < .05), indicating more effective usage of non‐protein energy. Furthermore, creatine supplementation also increased plasma insulin levels and upregulated IGF‐1 and GLUT4 gene expressions in the liver significantly; it also improved robustness against stress, which was shown by higher superoxide dismutase, higher postchallenge survival and plasma cortisol, malondialdehyde and lower glucose levels. In conclusion, creatine supplementation at a dose of 0.289–0.389 g/kg diet escalated fish growth and improved robustness against stress via improving the SOD activity in red tilapia.     

Efficacy of koi herpesvirus DNA vaccine administration by immersion method on Cyprinus carpio field scale culture

Koi herpesvirus specifically infects and causes mass mortality on koi and carp, resulting in severe economic losses. In this study, we presented the efficacy of KHV DNA vaccine administration by immersion method on Cyprinus carpio. Two different immersion densities of fish were applied, namely 800 fish L^?1 and 1200 fish L^?1. Thirty‐day‐old common carp juveniles were immersed for 30 min in the water containing 1.3 × 10⁸ CFU mL^?1 of heat‐killed Escherichia coli carrying DNA vaccine encoding glycoprotein‐25, and without vaccination treatment as controls. The challenge test was performed at 30 days post vaccination by injecting 0.1 mL KHV filtrate (10^?3 of dilution rate). The result showed that higher relative per cent survival of KHV‐challenged fish was obtained in 800 fish L^?1 (P < 0.05). Furthermore, significant specific antibody anti‐KHV response (P < 0.05) was detected on 28 and 36 days post vaccination in 800 and 1200 fish L^?1, respectively, compared to the controls there was no specific antibody detected. In conclusion, the KHV DNA vaccine could provide good protection in common carp against KHV infection, which has practical applications in aquaculture practices.     

Transgenic Nile tilapia (Oreochromis niloticus) over-expressing growth hormone show reduced ammonia excretion

The growth of aquaculture has negatively affected the environment due to the high levels of nitrogen excreted by farmed fish. Here we propose that modifying the nitrogen metabolism of the fish themselves using transgenic technology might solve the pollution problem. Growth hormone (GH) is known to increase protein retention and absorption, and is thought to reduce ammonia excretion. Thus, we produced transgenic Nile tilapia (Oreochromis niloticus) that over-expressed the GH gene throughout their bodies. Our findings showed that the food-conversion efficiency of the transgenic fish was 35% higher than that of their non-transgenic siblings. The rearing period required for the transgenic fish to reach a body weight of 20 g was about 75% of that required for non-transgenic fish that were fed the same type and quantity of food. The total amount of ammonium-nitrogen excreted by the transgenic fish was about 69% of that excreted by the wild-type fish over their lifetime. These results suggest that our transgenic approach has the potential to reduce the amount of nitrogen pollution caused by farmed fish. This strategy is a promising option for making aquaculture more ‘eco-friendly’.     

Resistance to vibriosis,production performance and tolerance to stress of the selected giant freshwater prawn (Macrobrachium rosenbergii)

The purpose of this study was to evaluate the resistance to vibriosis, growth, survival and tolerance to stress of the selected prawn, second generation, compared to a non‐selected control. The first generation of selected giant freshwater prawn, which has 10.4% higher of resistance, was used to attain disease resistant freshwater prawn (Macrobrachium rosenbergii) generation through challenge test‐based selection. Resistance test was conducted by infecting the prawn (mean body weight of 10.29 ± 1.40 g) with pathogenic Vibrio harveyi (5 × 10⁵ cfu prawn^?1). The growth and survival of the prawn were evaluated by rearing the two populations of prawn in both nursery and grow‐out phases. Stress tolerance test was done by evaluating the viability of postlarvae exposed to environmental stressors, i.e. temperature, salinity, NH₃ and formaldehide. Post‐challenge survival of the selected prawn (55.0 ± 5.0%) was about 46% higher than that of the control (37.5 ± 7.5%). The survival of the selected prawn in nursery culture (77.16 ± 0.841%) was significantly higher (p < .05) than that of the control (51.31 ± 2.938%), while the survival in grow‐out culture was similar (p > .05). The growth of selected prawn (4.99 ± 0.03% day^?1) was significantly higher than that of the control (4.81 ± 0.05% day^?1). There was no difference between treatments on the tolerance level against the tested environmental stressor. Overall data suggested that the selected prawn showed better performance in growth and resistance against vibriosis.     

Growth,biochemical composition,innate immunity and histological performance of the juvenile humpback grouper (Cromileptes altivelis) after treatment with recombinant fish growth hormone

Humpback grouper take a long time to grow to marketable size. In this study, recombinant Epinephelus lanceolatus growth hormone (rElGH) was applied orally and by intraperitoneal injection to accelerate their growth. Daily application of crude rElGH at a dose of 50 mg kg^?1 in commercial diet for 42 days or with injections of 0.2 μg rElGH g^?1 total body weight every 2 weeks resulted in significant increases in growth performance, protein and lipid content, plasma glucose, liver glycogen and innate immunity compared to control groups. Relative weight gain from the oral and injection doses above compared to C? (Control negative, only commercial diet without rElGH treatment or chemical substances related to treatment, either for oral or injection route) were 40.25% and 38.77%, respectively. There was no specific histological damage to the kidneys, liver or spleen that was attributable to rElGH administration. These results strongly suggested that the stimulation of growth and immunity following oral and intraperitoneal administration was due to a specific action of rElGH and that recombinant GH is safe for fish consumption.     

Development of primary cell culture from spleen of giant gourami Osphronemus goramy for propagation of giant gourami iridovirus (GGIV)

The severe mortality of fish due to the infection of megalocytivirus caused significant economic losses. Since 2011, megalocytivirus (giant gourami iridovirus (GGIV)) has become the main pathogen in giant gourami (Osphronemus goramy), particularly in West Java, Central Java and Bali. This study aimed to develop primary cell culture from spleen as the target organ for propagating megalocytivirus in vitro, which was developed by explant method with enzymatic dissociation. Optimization was carried out at incubation temperature, medium and serum concentrations. The origin of the primary cell, cell susceptibility and GGIV pathogenicity were observed. The results showed that the primary cell (GP cells) can grow well in 10% foetal bovine serum L-15 medium at 27°C, which was sufficient for cell growth. PCR and BLAST analyses showed the primary cell was originated from giant gourami. In infected GP cells, cell enlargement and cell rounding were observed. Virus propagated in GP cells was highly virulent when injecting giant gourami in an artificial infection experiment. Intraperitoneal injection of diluted virus supernatant showed 100% mortality in 7–11 days post-injection and 97% mortality in 21 days post-cohabitation, with abnormalities observed in spleen and kidney. In conclusion, GP cell was successfully subcultured for more than 30 passages and susceptible to GGIV.