Bacterial population in intestines of white shrimp,Litopenaeus vannamei fed a synbiotic containing Lactobacillus plantarum and galactooligosaccharide

The aims of this study were to unravel the intestinal microbiota of Litopenaeus vannamei after being fed a diet without (control) or with the synbiotic (SYN) for 60 days using next‐generation sequencing technology to see if changes in the intestinal microbiota were involved in the improved growth performance and health status of the shrimp. Next‐generation sequencing data showed that six phyla, 11 classes, 19 orders, 30 families, 58 genera and 73 species with taxonomic names assigned were detected. The majority of the operational taxonomic units (OTUs) was shared between the SYN and control shrimp and comprised 37 OTUs. However, intestinal biodiversity analyses revealed that SYN‐fed shrimp had a higher species richness, evenness and Shannon–Weaver index than did shrimp fed the control diet, but without reaching statistical significance. Interestingly, shrimp fed the SYN diet exhibited improved colonization of Lactobacillus plantarum and reduced prevalences of Vibrio harveyi and Photobacterium damselae in the intestines. These findings indicate that the SYN was able to modulate the intestinal bacterial community of shrimp and could be used to control vibriosis in shrimp.     

Seasonal Changes in the Milt Quality of Waigieu Seaperch,Psammoperca waigiensis: Implications for Artificial Propagation

Milt quality of Waigieu seaperch was sampled at the beginning, the middle, and the end of the spawning season to assess if the sampling season has an effect on milt quality parameters. The milt volume and total sperm production were higher at the middle of the spawning season while the sperm concentration in milt was significantly higher at the beginning and the end of the spawning season. Sperm morphology and the major parameters of seminal plasma (pH, total protein, Mg²⁺, or Ca²⁺ concentrations) did not differ throughout the spawning season. The concentrations of Na⁺ and the osmolality increased throughout the spawning season. The percentage of motile cells did not differ during the spawning season while the duration of sperm motility (swimming duration) and velocity (swimming speed) were significantly different during the spawning season. The fertilization rate (75.7 ± 6.8%) and hatching rate (56.5 ± 3.1%) at the middle of the spawning season were higher than at the beginning and end periods. Results indicated that milt quality parameters and fertility success in the middle of the spawning season were higher compared to earlier and later sampling dates. Thus, we recommend collecting milt during this time for maximal fertilization and hatching success.     

Comparative energy and economic analyses of conventional and System of Rice Intensification (SRI) methods of rice production in Thai Nguyen Province,Vietnam

The consumption of energy inputs in agricultural production has been increasing rapidly during the past decades. However, given the limitations and costs of non-renewable energy, increasing production while using the least energy possible has become a major concern of most nations. Prompted by this concern, we conducted a face-to-face survey of 90 farming households in Thai Nguyen Province, Vietnam, to find out how energy is being used in agriculture and, specifically, in their rice production. Through analysis of energy input–output balances, combined with economic efficiency analysis, a comparison was made of conventional and SRI methods of rice production. The study found that applying the SRI method can save around 23% of energy inputs, while increasing energy outputs by 11%. Economic benefits per hectare also rise by more than 8 million dong (USD 364) compared to those under the conventional cultivation system. The study also showed conflicts between the energy and economic balances for manual compared with machine ploughing operations. This study contributes to providing an overview of energy consumption in rice cultivation at the household level. Its findings can help stakeholders to assess current policies and make better decisions on the uses of energy in agricultural production. In addition, the comprehensive approach taken here to analysing energy use and efficiency could expand the analysis and comparison of energy uses at sectoral or activity level—still a new field in Vietnam and many other countries.     

Data envelopment analysis for production efficiency improvement: An empirical application on brine shrimp Artemia franciscana culture in the Mekong Delta,Vietnam

Artemia culture in the Mekong Delta, Vietnam, is becoming more and more important to satisfy the global demands of cyst production. Nevertheless, Artemia cyst productivity in the Mekong Delta has been fluctuating largely due to not only technical inefficiencies and external factors but also farms’ characteristics. This study employed a data envelopment analysis to evaluate the production efficiencies in correlation with biological and cost inputs of Artemia culture in Vinh Chau and Bac Lieu located in the Mekong Delta. The key factors affecting technical efficiency (TE) were determined using ordinary least squares regression model. The empirical results indicated that production efficiencies of farms in Vinh Chau and Bac Lieu were similar with metatechnology ratios of 0.97 and 0.96 respectively. About 62.8% of surveyed farms were operating in technically inefficient circumstances. Farmers’ experience, educational level and culture technique training participation had positive effects on TE, while climate effects and water problems have been proved to have negative effects on TE. To improve production efficiency, inefficient farms are suggested to have moderately increasing combinations of organic fertilizer, chemical and feed. The use of probiotics should be reduced as it increases production cost and affects TE. Notably, a collaboration of scientists and feed processing companies is recommended to produce a specific formulated feed for Artemia in commercial scales. This study also proposes adaptive policies for local governments and cooperatives to assist coastal famers in the Mekong Delta overcome technical inefficiencies, improve cyst productivity and obtain economic sustainability in Artemia culture.     

Detection of Novel Reassortant Influenza A (H3N2) and H1N1 2009 Pandemic Viruses in Swine in Hanoi,Vietnam

From May to September 2013, monthly samples were collected from swine in a Vietnamese slaughterhouse for influenza virus isolation and serological testing. A(H1N1)pdm09 viruses and a novel H3N2 originating from reassortment between A(H1N1)pdm09 and novel viruses of the North American triple reassortant lineage were isolated. Serological results showed low seroprevalence for the novel H3N2 virus and higher seroprevalence for A(H1N1)pdm09 viruses. In addition, serology suggested that other swine influenza viruses are also circulating in Vietnamese swine.     

Resistance to Streptococcus iniae and its genetic associations with traits of economic importance in Asian seabass (Lates calcarifer)

Streptococcus iniae is one of the most serious aquatic pathogens, causing significant economic losses in marine and freshwater species, including Asian seabass (Lates calcarifer). Controlling this gram‐positive bacterial pathogen has been an issue in aquaculture systems, due to the combined effects of aquaculture intensification and climatic impacts. To date, there have not been any genetic parameter estimates for S. iniae resistance in Asian seabass. The main aim of this study was to examine genetic variation in S. iniae resistance and its genetic correlations with growth and cannibalism in Asian seabass families produced from a breeding programme for high growth in 2016 and 2017. The study included a total of 5,835 individual fish that were offspring of 41 sires and 60 dams (31 half‐sib and 34 full‐sib families). The experimental fish were challenged by intraperitoneal injection with a volume containing 10⁵ CFU (colony‐forming unit)/fish. Resistance to S. iniae was measured as survival rate at 6 hr, 3, 5, 7, 10 and 15 days post‐challenge test. There were significant variations in S. iniae resistance among families at different observation periods (ranging from 24.4% to 80%). Restricted maximum‐likelihood method and mixed model analysis were applied to estimate heritability for S. iniae resistance. The heritability for S. iniae resistance ranged from 7% to 18% across different statistical models used. The common full‐sib effects accounted for 0.1%–2% of the total variation in resistance to S. iniae. Genetic correlations of the S. iniae resistance at 6 hr and 3 days with later post‐challenge test periods were low to moderate. However, these estimates for S. iniae resistance between successive measurement times (5, 7, 10 and 15 days) were high and close to 1. The genetic correlations of resistance with body weights at 180, 270 and 360 days post‐hatch were not significant as well with cannibalism. It is concluded that there is substantial additive genetic variation in resistance to S. iniae, suggesting there is potential for genetic improvement of Asian seabass for resistance to S. iniae through selective breeding.     

Agrobacterium-mediated transformation of the CrDAT gene and selection of transgenic periwinkle lines with a high vincristine accumulation

Catharanthus roseus contains vincristine and vinblastine, which are outstanding drugs for cancer. In the biosynthetic pathways of terpenoid indole alkaloids (TIAs) in C. roseus, deacetylvindoline 4-O-acetyltransferase (DAT) is a key enzyme that catalyses the last reaction of vindoline biosynthesis to form vinblastine and vincristine. In this study, the CrDAT transgene was transferred into the periwinkle by Agrobacterium-mediated transformation and generated transgenic periwinkle lines with an increase in vincristine accumulation. The C. roseus DAT gene was introduced into C. roseus plants and it was confirmed that CrDAT was successfully transferred into the genome of periwinkle plants and efficiently translated to synthesise recombinant DAT protein. Four transgenic periwinkle lines in T1 generation, T1-1, T1-3, T1-6, and T1-7, expressed recombinant DAT protein with the total protein content in the range of 2.86 μg.mg^?1 to 5.12 μg.mg^?1. Moreover, the vincristine contents of four transgenic lines increased by 1.63?2.48-fold compared to non-transgenic plants, ranging from 6.91 µg.g^?1 (fresh weight) to 10.53 µg.g^?1 (fresh weight). The T1-1 line had the highest vincristine content. Hence, the overexpression of the recombinant DAT protein can improve the vincristine accumulation of transgenic C. roseus plants.

Abbreviation: CrDAT - Catharanthus roseus Deacetylvindoline-4-O-Acetyl Transferase; D4H - Deacetoxyvindoline 4-hydroxylase; ELISA - Enzyme-Linked Immunosorbent Assay Monoterpene indole alkaloid; T0, T1 - Generations of transgenic plants; TIAs - Terpenoid indole alkaloids; WT- The wild-type tobacco plants (non transgenic plant); 35S - Cauliflower mosaic virus 35S promoter     

Effects of Thyroxin and Domperidone on Oocyte Maturation and Spawning Performances in the Rabbit Fish,Siganus guttatus

Thyroxin (T₄) is proven to have various functions in fish reproduction. In this study, we investigated oocyte maturation and spawning performance in the rabbit fish, Siganus guttatus, orally exposed to different doses of T₄ (0.05, 0.25, and 0.5 mg/kg fish) during vitellogenesis. No statistically significant differences of reproductive characteristics were observed among the treatments. However, the group that was exposed to the dose of 0.5 mg/kg spawned after receiving a hormone injection. The findings suggest that feeding T₄ during vitellogenesis did not advance oocyte maturation, but probably could induce spawning in rabbit fish. In a separate experiment, we investigated the effects of orally administered domperidone (DOM) on reproductive performances of the female rabbit fish. The study showed that oral administration of DOM during the early stages of the reproductive cycle had no significant effects on oocyte maturation and spawning performance. Overall, these findings suggest that DOM may not be needed for the induction of maturation and spawning of this species under aquaculture conditions. These practical investigations were conducted with a view to attempt reducing drug use, production costs, and support sustainable aquaculture.