Published: 2018-08-28

Efficacy of florfenicol for control of mortality associated with Flavobacterium columnare in tilapia

Thinh H. Nguyen, & Hue N. D. Truyen
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.10.04.2018
Abstract | PDF (260.1K)

Abstract

The efficacy of florfenicol for control of mortality associated with Flavobacterium columnare was studied in tilapia. F. columnareT3-8/10 strain used for infection was tested for virulence by bath challenge to tilapia (body weight: BW 14 - 16 g) and antimicrobial sensitivity test. The results showed LD50 of this bacterial strain was 4.8 × 104CFU/mL and it was sensitive to florfenicol. Ex-periment for control mortality caused by the bacterium in tilapia (BW 18 – 20 g) was designed with four treatments including neg-ative control (unifected fish), positive control, NT10 and NT15 (infected with LD50). Just after infection, fish in positive control, NT10 and NT15 treatments were treated with florfenicol at doses of 0, 10 and 15 mg/kg BW/day for 10 days, respectively, by feed-ing fish with medicated feed. Mortality of fish in positive control treatment after 14 days of infection was 54.0 ± 5.47% and statisti-cally different in comparison with those in negative control, NT10 and NT15 treatments were 0.0, 3.0 ± 4.72 and 2.60 ± 2.51%, re-spectively (P < 0.05). Fish in NT10 and NT15 treatments were sampled for testing florfenicol residue in the flesh at day 1, 16, 20 and 24 after treatment. The results showed florfenicol residue levels in the flesh of sampled fish at all testing timepoints were sig-nificantly lower in comparision with the safe concentration lower than 1000 ppb regulated by the Ministry of Agriculture and Rural Development of Vietnam.

Isolation and identification of biological characteristics of porcine circovirus type 2 (PCV2) from pigs in southern Vietnam

Phuong T. T. Le, Hai N. Nguyen, Hong T. T. Nguyen, Ngon V. Quach, Phuc N. H. Nguyen, Liem T. Nguyen, Hanh X. Tran, Dung V. Nguyen, & Hung Dang
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.9.04.2018
Abstract | PDF (260.1K)

Abstract

This study aimed to isolate and examine the biological char-acteristics of PCV2 field strains circulating in Vietnam for further study in producing vaccine against PMWS (postweaning multisystemic wasting syndrome). Eighteen PCV2 strains were successfully isolated and belonged to genotype PCV2b (9 strains), PCV2d (6 strains) and recombinant (3 strains). The viral titers of PCV2 isolates at the third passages in PK15A cells were in the range from 1.67 to 5,50 log10TCID50/mL. Three PCV2 field strains with stable viral titers (≥5,0 log10TCID50/mL) through passages, which belonged to different genotypes, were selected as master seed for studying of PCV2 vaccines.

Minimum inhibitory concentration (MIC) determination of herbal extracts against Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus

Tien T. Tran, An T. T. Vo, Vu T. Pham, Tue T. Nguyen, Nga T. T. Tran, Vu Tran, & Hien B. T. Le
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.8.04.2018
Abstract | PDF (260.1K)

Abstract

The objective of this study was to determine the minimum in-hibitory concentration (MIC) of crude extract from five medical herbs in Vietnam (Camellia sinensis, Eclipta prostrata L., Pseud-eranthemum palatiferum, Psidium guajava, Azadirachta indica) against Escherichia coli ATCC25922, Salmonella Typhimurium, Staphylococcus aureus ATCC25923 by macro - dilution method. These results were the basis for the application of these herbs in the prevention and treatment of diseases in animals. The re-sults showed that MICs of Camellia sinensisagainst E.coli, S. Ty-phimurium, and S. aureuswere 8 - 16 mg/mL, 8 - 16 mg/mL, 0.5 mg/mL respectively; MICs of Eclipta prostrata L.against E.coli, S. Typhimurium, and S. aureus were 16 mg/mL, 16 mg/mL, 1- 2 mg/mL respectively; MICs ofPseuderanthemum palatiferumagainst E.coli,S. Typhimurium andS. aureus were 8 mg/mL, 4- 8 mg/mL, 2 - 4 mg/mL respectively; MICs of Psidium guajava against E.coli,S.Typhimurium andS. aureus were 16 mg/mL, 16mg/mL, 0.125 – 0.25 mg/mL respectively and MICs of Azadirachta indicaagainst E.coli,S.Typhimurium, and S. aureus were more than 16 mg/mL.

Determination of some conditions for hairy root induction in soybean by Agrobacterium rhizogenes

Phong V. Nguyen, Linh B. Tun, Trinh T. T. Ngo, & Vu X. Le
Electronic version: 28 Aug 2018 | DOI: 10.52997/jad.11.04.2018
Abstract | PDF (260.1K)

Abstract

This study was conducted to determine some conditions for transformation via Agrobacterium rhizogenes on soybean cultivars HLDN29 and DT84. Cotyledon explants were more efficient in hairy root induction compared with hypocotyl explants in both cultivars of soybean. The highest root induction rate and average root number were observed in HLDN29 explants infected with ATCC11325 and ATCC15834 strains (approx. 96% - 100%and 8 roots per explant) and in DT84 explants infected withATCC15834. Six to eight day – old cotyledonary leaves after sowing were optimal and appropriate for hairy root induction. Direct inoculation and immersion methods showed no significant difference in root induction rate and average root number in both HLDN29 and DT84 cultivars. Transgenic root lines were identified based on PCR analysis with virD và rolC sequences –specific primers.

Harvesting of Chlorella vulgaris grown in closed-photobioreactor with chitosan for use in food

Vinh Truong, Vy T. Truong, Tu T. C. Ho, Dat Q. Nguyen, & Thuy T. T. Nguyen
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.13.04.2018
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Abstract

Chlorella vulgaris was cultured in chemostat mode and harvested on a semi-continuous basic with 50% of broth volume every two days, giving the highest biomass yield. The flocculation efficiency of microalgae using chitosan depended on dose use, quality of chitosan such as degree of deacetylation (DD) and solubility. The flocculation efficiency was 99% after 30 minute, and 95% after 10 minute for DD of 87% and 89.8%, respectively. Chlorella vulgaris grown in 500 liter-tubular photobioreactor using Basal medium was harvested semi-continuously by three washing times in 2% acetic acid following chitosan flocculation to obtain clean biomass with lower 2% chitosan content (w/w). Analysis of physicochemical composition of algal biomass showed no heavy metal, reaching microbiological criteria, containing outstanding natural nutrients such as protein, lipid, chlorophyll superior to some other food materials. These nutrients are the essential components for human body, suitable for functional food application.

Investigation on the use of chloramphenicol and amoxicillin in snakehead fish (Channa maculata) farming and analysis of those antibiotic residue in muscle samples

Thao V. Ngo, Phu Q. Nguyen, Ngoc V. Ngu, & Lam D. Ngo
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.15.04.2018
Abstract | PDF (260.1K)

Abstract

The use of drugs and chemicals in aquaculture has been increased surprisingly due to the fact that it has been moving from low to high level of intensification. However, there is lack of information in snakehead fish farming. The study was conducted by interviewing 65 farmers in Dinh Quan, Trang Bom, and Bien Hoa, Dong Nai province to provide sufficient information on the use of chloram-phenicol (CAP) and amoxicillin (AMX) in snakehead fish farming. Interview results showed that no employment of the 2 antibiotics in prevention of diseases. However, CAP was currently applied to treat diseases at a concentration of 50.04 and 100.0 g/ton of fish in Bien Hoa and Trang Bom, respectively despite it was banned in aquaculture according to the law. AMX restricted to use was employed when fish got sick at 59.62, 91.49, and 89.58 g/ton of fish in Dinh Quan, Bien Hoa and Trang Bom, respectively. In contrast to field survey result, LC-MS/MS analysis of 3 fish muscle samples randomly collected at each place around 14 days before and on the day of harvesting indicated that no residue of concerned antibiotics was detected. The present study suggests that farmers currently apply antibiotics including banned antibiotics in fish but have initially raised awareness of the use of antibiotics, evidenced by the fact that they were only used when needed. Hence, the management and extension should be intensively promoted for a legal use of antibiotics and other chemicals.

Enzymatical hydrolysis of proteins from Tra fish flesh scrap

Thien T. Le, Thuy T. Bui, & Ngan N. T. Trinh
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.14.04.2018
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Abstract

The study was carried out to compare types of enzymes and to evaluate effects of conditions for hydrolysis of Tra fish flesh scraps. Among the four experimented enzymes including protamex, papain, neutrase, and alcalase, the last one was the most efficient in term of protein recovery yield and hydrolysis degree. The hydrolysis efficiency was at the maximum at conditions of pH 8.0, the temperature 550C and the rate of enzyme/material 1.0%. At these conditions, the protein recovery yield was over 70%, and hydrolysis degree was over 18%. The results of the research provide a background to apply enzymes to convert Tra fish flesh scraps into a protein hydrolysate to be used as a functional ingredient or to be used in functional foods.

Farmers’ satisfaction with agricultural extension service quality in Ninh Phuoc district, Ninh Thuan province

Hoang M. Do, & Nam H. Tran
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.1.04.2018
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Abstract

Agricultural extension service quality is a key to sustainable development and enhances the efficiency of government resources for farmers. This paper assessed farmer’s satisfaction with the quality of agricultural extension services in Ninh Phuoc district, Ninh Thuan province. Major analytical tools included: exploratory factor analysis (EFA), confirmatory factor analysis (CFA) and structural equation modeling (SEM). The data were collected by direct interviews with 320 farmers participating on the extension. The analysis results showed that the level of satisfaction of the farmers was significantly influenced by the quality of the agricultural extension service and the agricultural extension service quality was influenced by factors such as farmers’s adoption of technological innovations in agriculture, the extension staff’s clear presentation and understandable in-structions to farmers, experienced trainers, exciting and pleasant discussions and field trip activities tailored to the needs of farmers.

Designing landscape Him Lam Phu An apartment in district 9, Ho Chi Minh city with “skyrise greenery” tendency

Duyen T. M. Nguyen, & Tien T. M. Duong
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.12.04.2018
Abstract | PDF (260.1K)

Abstract

The research carried out in the Ho Chi Minh city, from September 2016 to January 2017, aimed to green infrastructure planning, environmental restoration for apartment park, giving green space for citizens. It was conducted with some methods as: site analysis, find a function for the area, computer aided design and drafting base on main idea. We proposed two design ideas and chose the best idea for concept design, propose the instant tree list, the shrub list, the material and furniture list. Document design included: function layout plan, master plan, elevations, sections and some details of park, master perspective, detail perspectives.

Selection of green super rice (GSR) with high yield, good qualities, and adaptation to climate condition in Phu Yen province (Part one)

Tung T. Nguyen, KIM HOANG, Long Hoang, Thang D. Nguyen, Thoa T. Pham, Ton T. Dam, Mai T. T. Nguyen, Zheng Tian-Qing, & Li Zhikang
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.6.04.2018
Abstract | PDF (260.1K)

Abstract

It’s very important and urgent to select the green super rice (GSR) vari-ety which can adapt to climate changes in Vietnam. Phu Yen rice is the main granary of the South Central Coast, with the area of two-crop rice of nearly 52,000 ha. The production of high-productivity, good-quality and climate-smart rice to make the high-quality rice brand for Phu Yen is very urgent and important. The project "Selection of Green Su-per Rice (GSR) variety of high-productivity, good-quality and climate condition adaptation in Phu Yen Province" implemented by Phu Yen Center for Plant Breeding and Technology. The contents of the study included: basic experiment, production experiment, establishment of demonstration models of trial production of two new rice varieties, se-lection and experiment for development of rice cultivation techniques for Tuy Hoa delta area. This report presents part 1: Results of basic experiment of the green super rice (GSR) variety in Phu Yen province. The basic experimental materials included 12 selected rice varieties and 9 green super rice varieties GSR36, GSR38, GSR54, GSR63, GSR90, GSR84, GSR89, GSR90 and GSR131 and two promising rice varieties Nam Uu 1241, Nam Uu 1245 and ML 48, known as the most common control rice variety in the locality. The study focused on six formal experiments implemented over three crops (winter - spring crop-2015, summer - august crop 2015 and winter - spring crop 2015-2016) in the intensive cultivation area, Hoa An Agricultural Variety Farm and Hoa Dong Agricultural Variety Farm, Phu Yen Province. Experimental method was implemented in accordance with National Technical Regulation QCVN 01-55: 2011/BNNPTNT Experiment on value of cultivation and use value of rice varieties. The six basic experiments over three crops contributed to the selection of 4 GSR65, GSR90, GSR38, Nam Uu 1245 rice varieties with high-productivity, good-quality, good agrobiological features, short growth time (A1), low pest infestation for production experiment and construction of demonstration model in farming field in Phu Yen province.

Effects of topping times on growth and yield of three sweet basil (Ocimum basilicum L.) varieties cultivated in the net house

Tam T. M. Pham, & Hue T. Nguyen
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.3.04.2018
Abstract | PDF (260.1K)

Abstract

The study was carried out from June to December, 2014. The objective of this study was to determine a suitable topping time for sweet basil variety grown in the net house at Research and Development Center for Hi-Tech Agriculture Ho Chi Minh City. A two factorial experiment was designed by the CRD (Completely Randomized Design) with three replications. Factor A consisted of three sweet basil varieties (TN12 as Control, TN33, and TN39) and the factor B was the topping times including untopping (the control), the topping when sweet basil at the four - leaves, at the six - leaves and at the eight – leaves period. The results showed that variety TN39 was suitable for extracting basil-oil because of the highest yield (3,365.4 kg/1,000 m2) and high total essential oil content (0.25%). Variety TN12 could be grown for fresh-eating spicy. The variety TN12 resulted in the fairly high yield (1,955.4 kg/1,000 m2) and total essential oil content (0.20%) with good taste. Topping the basil plant at the six – leave period reached the highest yield of 2,172.3 kg/1,000 m2.

Structural characteristics, quality and plant biodiversity in forest types at Xuan Son national park, Phu Tho province

Trieu V. Nguyen, & Hung M. Bui
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.7.04.2018
Abstract | PDF (260.1K)

Abstract

Forest structure plays a very important role in the sustainable management of forest resources. Research established 20 plots. The plot area is 900 m2(30 m×30 m) for 4 forest types: IIA, IIB, IIIA1 and IIIA3. Results showed that average diameter of four stages is IIA: 11.25 cm; IIB: 12.81 cm; II: 1: 15.94 cm and IIIA3: 20.30 cm. The mixed linear model demonstrated that growth in both diameter and height between forest states was significantly different (P < 0.05). Weibull and J-shape functions can simulate well for 75% of experimental distributions. Path analysis showed that for all four states, direct influence (AHTT) had a greater absolute value than the indirect effect (AHGT). Principal component analysis diagrams showed that for all four types, the quality of forest trees was closely related to canopy width, total height and diameter at breast height. The difference in the quality of the trees between the four states was really significant, as the Sig value of the Chi-square test is 0.000 (less than 0.05). Stages IIA and IIB had mainly species of pioneer species, while IIIA1 and IIIA3 had more shade tolerant species. Stage IIIA3 had the highest level of species diversity.

The effects of plant spacing and frequency of aeration on the growth and yield of water dropwort (Oenanthe javanica (Blume) DC.) in hydroponic system

Hoang T. Nguyen, Tam T. M. Pham, Trang T. N. Nguyen, & Thuan T. Q. Nguyen
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.4.04.2018
Abstract | PDF (260.1K)

Abstract

Water dropwort is an aquatic perennial plant of the Apiaceae family and is a wild vegetable originating in the tropics of Asia. The plant prefers moist soil and growing in partial shading 60 - 70% conditions. The two factor experiments were arranged in randomized complete design (RCD) with three replications. Factor A was four planting spaces (4 × 2 cm; 4 × 3 cm; 4 × 4 cm and 4 × 5 cm). Factor B was frequency of aeration (every two days; every four days and every six days). Results showed that water dropwort planted in watercress nutritious solution at different planting spaces and frequency of aeration had no statistically significant effect on height, number of leaves/plant, average plant weight as well as quality indicators. However, water dropwort planted in watercress nutritious solution with 4×2 cm spacing and aerating for highest theoretical yield, actual yield and commercial yield are 3,408 kg/1,000 m2; 2,504 kg/1,000 m2and 1,979 kg/1,000 m2.

Selection of green super rice (GSR) with high yield, good qualities, and adaptation to climate condition in Phu Yen province (Part two)

Tung T. Nguyen, KIM HOANG, Long Hoang, Thang D. Nguyen, Thoa T. Pham, Ton T. Dam, Mai T. T. Nguyen, Zheng Tian-Qing, & Li Zhikang
Electronic version: 31 Aug 2018 | DOI: 10.52997/jad.5.04.2018
Abstract | PDF (260.1K)

Abstract

The research contents included: basic experiment, production experi-ment, demonstration trial production of two new rice varieties selected and experimental development of rice cultivation techniques for Tuy Hoa plains. This report presents part two: Results of production exper-iment, demonstration trial production of two new rice varieties selected in Phu Yen province. The study was conducted in 4 seasons (Winter-Spring 2015 - 2016, Summer-Autumn 2016, Winter-Spring 2016 - 2017 and Summer-Autumn 2017) at intensive farming soil area in Hoa My village of Phu Hoa district, and Hoa Thang village of Tay Hoa dis-trict, Phu Yen province with 4 advanced rice varieties (GSR65, GSR90, GSR38 and Nam Uu 1245) and ML 48 used as control. Experimental method in accordance with National Technical Regulation QCVN 01-55: 2011/BNNPTNT Experiment on value of cultivation and use value of rice varieties. Results of the four production experiments in two se-lected crops and the four demonstration trial production of two new rice varieties selected, two the GSR65, GSR90 rice varieties had high yield, good quality, good agronomic traits, short growing time (A1), low pest infestation, suitabe for export and success construction demonstration model on farmer field in Phu Yen.The GSR65 and GSR90 varieties gave the average yield of 79.8 and 81.7 quintals/ha, exceeding 11.92% and 14.58% respectively compared to control ML48 reaching 71.3 quintals/ha, and the profit was 30.5-36.7% higher than that of ML48 at 15.50 million VND/ha. The GSR65 and GSR90 rice cultivation techniques have been developed.