Evaluation of local feed resources for hybrid catfish (Clarias macrocephalus x C. gariepinus) in smallholder fish farming systems in central Vietnam

The aim of this thesis was to examine the current feeding situation for fresh water fish in Central Vietnam, to evaluate the potential nutritive value of locally available feed resources for hybrid catfish (Clarias macrocephalus x C. gariepinus) and Nile tilapia, to determine the dietary requirement of lysine for hybrid catfish, to estimate the requirements for the other essential amino acids (EAA) by using ideal protein concept, and finally to evaluate the suitability of cassava leaf meal and shrimp head meal as a partial replacement for fish meal in the diet, without or with lysine supplementation, for hybrid catfish fingerlings. The survey indicated that, in total, 22 feed ingredients were used by the farmers. The main ingredients were cassava root meal, rice bran, cassava residue, groundnut meal, soybean meal and fish meal. Furthermore, several more unconventional feedstuffs were also commonly used, such as cassava leaves, coconut meal, shrimp head meal, sesame husk and squid by-product. The combination of ingredients used in farm-made fish feeds varied among farms and districts leading to a large variation of nutrient composition and energy content. The fish yield varied among districts and ranged from 0.8 to 6.5 t ha-1. The digestibility trial showed that the apparent digestibility (AD) of dry matter (DM), organic matter (OM) and crude protein (CP) in cassava leaf meal was significantly lower than in groundnut meal, soybean meal, sesame husk meal and shrimp head meal in both hybrid catfish and Nile tilapia. The AD of DM and OM in cassava leaf meal was higher in hybrid catfish than in Nile tilapia. Most EAA in the selected feedstuffs were equally well utilized by the two fish species. In the third experiment, the dietary lysine requirement of hybrid catfish fingerlings was found to be 56 g kg-1 of CP, corresponding to 16.8 g kg-1 of dry diet. In the feeding trial with hybrid catfish, replacing fish meal with shrimp head meal had no effect on final weight (FW) and specific growth rate (SGR), while replacing fish meal with cassava leaf meal led to impaired FW and SGR. Supplementing cassava leaf meal and shrimp head meal diets with lysine improved FW and SGR

Isolation and determination of Vibrio spp. pathogen from Sciaenops ocellatus suffering from hemorrhagic disease under cage culture in Vietnam

This study was carried out to isolate and determine the Vibrio spp. from the Red drum fish (Sciaenops ocellatus) suffering from the hemorrhagic disease in Vietnam.  In this study, 18 strains of Vibrio bacteria were identified from 27 samples of Red drum fish. The isolated bacterial strains were identified with the 16S rRNA sequencing method and checked for morphological, physiological, and biochemical characteristics by using the API 20E KIT. Results of the study revealed the presence of twelve strains of V. alginolyticus, three strains of V. fluvialis, and three strains of V. orientalis. All Vibrio strains have gene similarities with those on the Genbank ranging from 98.05 to 100%. The biochemical characteristics of these 18 isolates were similar and these are susceptible to tetracycline and doxycycline and entirely resistant to ampicillin, amoxicillin, and erythromycin

Effects of protein levels of commercial diets on the growth performance and survival rate of rabbitfish (Siganus guttatus) at the nursing stage

This study aimed to determine the effect of a commercial diet's protein level on the fry-to-fingerling stage. Thirty days-old fries having the initial length and weight of 18.25 ± 0.15 mm fish-1 and 0.036 ± 0.50 g fish-1 respectively have been used in this study. Diet having three protein levels i.e. 30% (trial 1 as control), 35% (trial 2), 40% (trial 3), and 45% (trial 4), respectively, have been used to evaluate the effect of protein, and each trial has been repeated three times. During the study, stocking density was allocated to 1000 fish per composite tank with a volume of 1 m3. After 30 days of rearing, the weight of fingerlings in trial 1 reached up to 1.50 ± 0.02 g fish-1 and it was recorded as 1.52 ± 0.01g for trial 2, these two were lower than that of trials 3 and 4, where fingerling weight was reported 1.69 ± 0.01 and 1.58g fish-1 respectively and obtained the best weight compared to others. The length of fingerlings at the end of the experimental period was also changed in different trials and it was recorded 47.12; 46.92; 50.97; and 48.89 mm fish-1 for trail 1, 2, 3, and 4 respectively, among the tested combinations lower fingerlings length was recorded for trial 2 (35% CP), but it is not significantly different for trial 1 and 2 and a significant difference (P < 0.05) was reported for trail 2, 3, and 4. The survival rate of fingerlings ranged from 67.27 to 72.33%. Meanwhile, the herd distribution coefficient variation (CVW) in the treatment using 40% protein (trial 3) was the highest at 72.33% (p < 0.05). The results of the study can be concluded that the level of protein has a significant effect on the various growth parameters of fingerlings

Development of a diagnostic scar marker for Vibrio shilonii caused acute hepatopancreatic necrosis disease in whiteleg shrimp

Background: In a previous report, we showed that Vibrio shilonii was found on whiteleg shrimp (Litopenaeus vannamei) with acute hepatopancreatic necrosis disease in Thua Thien Hue province, Vietnam. This study was performed to develop a diagnostic molecular marker generated by random amplified polymorphic DNA (RAPD) for V. shilonii rapid detection.Methods: Pathogen Vibrio spp. were isolated from shrimps and fishes, and were identified by 16S rRNA sequencing. Genetic diversity of Vibrio strains was analysis by RAPD technique. Specific PCR product for V. shilonii was cloned and sequenced. SCAR marker was developed from specific PCR product.Result: Twenty random primers were evaluated for RAPD to identify DNA polymorphisms between Vibrio species. The random primer OPN-06 generated a 468-bp DNA fragment specific for V. shilonii. This was then converted into a sequence-characterized amplified region (SCAR) marker designated N6-441.Conclusion: Specific primers (Vshi-441F/Vshi-441R) amplified a unique DNA fragment in all V. shilonii isolates but not in the other Vibrio spp. This PCR assay showed significantly sensitive to the target DNA and reliably for the amplification the V. shilonii genome.Keywords: AHPND; RAPD; SCAR; Vibrio shilonii; Vietna

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Projections of Future Climate Change in the Vu Gia Thu Bon River Basin, Vietnam by Using Statistical DownScaling Model (SDSM)

Future projections of anthropogenic climate change play a pivotal role in devising viable countermeasures to address climate-related risks. This study strove to construct future daily rainfall and maximum and minimum temperature scenarios in Vu Gia Thu Bon river basin by employing the Statistical DownScaling Model (SDSM). The model performance was evaluated by utilizing a Taylor diagram with dimensioned and dimensionless statistics. During validation, all model-performance measures show good ability in simulating extreme temperatures and reasonable ability for rainfall. Subsequently, a set of predictors derived from HadCM3 and CanESM2 was selected to generate ensembles of each climatic variables up to the end of 21st century. The generated outcomes exhibit a consistent increase in both extreme temperatures under all emission scenarios. The greatest changes in maximum and minimum temperature were predicted to increase by 2.67&ndash;3.9 &deg;C and 1.24&ndash;1.96 &deg;C between the 2080s and reference period for the worst-case scenarios. Conversely, there are several discrepancies in the projections of rainfall under different emission scenarios as well as among considered stations. The predicted outcomes indicate a significant decrease in rainfall by approximately 11.57%&ndash;17.68% at most stations by 2099. Moreover, all ensemble means were subjected to the overall and partial trend analysis by applying the Innovative-Şen trend analysis method. The results exhibit similar trend patterns, thereby indicating high stability and applicability of the SDSM. Generally, it is expected that these findings will contribute numerous valuable foundations to establish a framework for the assessment of climate change impacts at the river basin scale

The effectiveness of light emitting diode (LED) lamps in the offshore purse seine fishery in Vietnam

Fishing with artificial light has become one of the most advanced, efficient, and common methods for the night-time purse seining in Vietnam. This study evaluated the radiation spectrum, CIE chromaticity coordinates, correlated color temperature (CCT), catch rate, fuel consumption, and CO2 emissions when using Light emitting diode (LED) lamps (0.196 kW) in comparison with the use of metal halide (MH) lights (1 kW) in the offshore purse seine fishery in Quang Tri province, Vietnam. The fishing efficiency of the purse seine fishing boats using LED lamps has increased 1.58 times in catch rate than MH lights, although the energy consumption of LED lamp is 4 times smaller. Fuel consumption of boats per trip using LED lamps was one third of that using MH lights. The use of LED reduced the radiation spectrum, especially the intense UV radiation which negatively affects the health of fishermen. This study also showed the potential of CO2 emission reduction up to 1.09 tons of CO2 per trip per boat from the use of LED lamps in the offshore purse seine fishing boats

HIỆN TRẠNG NUÔI HÀU TẠI ĐẦM LẬP AN, THỊ TRẤN LĂNG CÔ HUYỆN PHÚ LỘC, TỈNH THỪA THIÊN HUẾ

Five species of oysters are cultured in Lap An lagoon, namely Crassotrea rivularis, Crassotrea gigas, Crassotrea sp1., Crassotrea sp2., and Saccostrea cucullata, among them Crassotrea rivularis is dominant. The most common farming method is using wooden stakes with old rubber tires. The total area of farming is 129 ha with an average of 2.08 ha/household. The oysters are farmed in five villages with different farming areas, with 35.8 ha (28%) being the largest and 16.1 ha (12%), the smallest. The highest production is 11.06 tons/crop/household, and the lowest is 5.56 tons/crop/household. The highest productivity is 4.46 tons/ha/crop, and the lowest is 3.81 tons/ha/crop. The highest income is 128.5 million VND/service/household, and the lowest is 37.3 million VND/service/household. The highest rate of return is 7.1, and the lowest is 3.02.Năm loài hàu đang được nuôi ở đầm Lập An bao gồm Hàu Cửa Sông (Crassotrea rivularis), Hàu sữa Thái Bình Dương (Crassotrea gigas), Hàu Mỏ vịt (Crassotrea sp1.), Hàu Ốc (Crassotrea sp2.) và Hàu Đá (Saccostrea cucullata), trong đó Hàu Cửa sông (Crassotrea rivularis) là loài xuất hiện nhiều nhất. Hàu được nuôi phổ biến trên giá thể lốp cao su. Tổng diện tích nuôi là 129 ha với trung bình 2,08 ha/hộ. Hàu đang được nuôi ở năm thôn với diện tích khác nhau: lớn nhất là 35,8 ha (28%) và nhỏ nhất là 16,1 ha (12%). Sản lượng hàu nuôi cao nhất là 11,06 tấn/vụ/hộ và thấp nhất là 5,56 tấn/vụ/hộ. Năng suất cao nhất là 4,46 tấn/ha/hộ và thấp nhất là 3,81 tấn/ha/hộ. Thu nhập cao nhất là 128,5 triệu đồng/vụ/hộ và thấp nhất là 37,3 triệu đồng/vụ/hộ. Tỷ suất lợi nhuận trung bình cao nhất là 7,1 và thấp nhất là 3,02

XÁC ĐỊNH SỰ CÓ MẶT CỦA CÁC GEN ĐỘC TỐ Ở CÁC CHỦNG Vibrio GÂY BỆNH HOẠI TỬ GAN TỤY CẤP TÍNH TRÊN TÔM THẺ CHÂN TRẮNG TẠI THỪA THIÊN HUẾ

Acute hepatopancreatic necrosis disease (AHPND) is a disease caused by bacteria, with the death ratio up to 100% in the population of Litopenaeus vannamei and Penaeus monodon, and causes great economic losses to many shrimp‐producing countries in Asia. Previous studies have shown that not all strains of Vibrio can cause AHPND because they contain different toxin genes, such as pirAvp, pirBvb, tlh, trh, and tdh. In this study, we evaluate the presence of several toxic genes on Vibrio isolates from Thua Thien Hue province and analyze the sequence of these genes. The results show that in 14 Vibrio strains carrying pirABvp gene, the tlh and toxR genes occur in 14/14 and 7/14 strains, respectively, while none of them have the two genes of trh and tdh. Analyzing the sequence of four DNA fragments shows that these genes have high similarity (98–100%) compared with the genes announced on the Genbank. Genes pirAvp and pirBvp are less different, while tlh and toxR genes are more different. The results could be used for further studies in the production of bioproducts for the prevention and treatment of acute hepatopancreatic necrosis disease in shrimp.Bệnh hoại tử gan tụy cấp tính (Acute Hepatopancreatic Necrosis Disease – AHPND) là một bệnh do vi khuẩn gây ra. Bệnh này dẫn đến tỷ lệ chết lên đến 100% trong quần thể tôm thẻ chân trắng, tôm sú và gây những tổn thất kinh tế đáng kể cho ngành nuôi tôm ở nhiều nước châu Á. Các nghiên cứu trước đây cho thấy không phải chủng Vibrio nào cũng có khả năng gây bệnh do chúng mang các gen độc tố khác nhau. Chúng tôi đã đánh giá sự có mặt của các gen độc tố trên các chủng Vibrio phân lập tại Thừa Thiên Huế đồng thời phân tích trình tự các gen này. Kết quả cho thấy trong 14 chủng Vibrio mang gen pirABvp nghiên cứu, gen tlh xuất hiện ở tất cả các chủng, gen toxR xuất hiện ở 7/14 chủng trong khi đó các gen trh và tdh không xuất hiện trong các chủng vi khuẩn Vibrio phân lập được. Giải trình tự đoạn chỉ thị các gen độc tố cho thấy các gen này đều có độ tương đồng khá cao (98–100%) so với các gen đã công bố trên ngân hàng gen, trong đó 2 gen pirAvp và pirBvp ít sai khác còn các gen tlh và toxR có sự sai khác nhiều hơn. Đây là cơ sở để thực hiện các nghiên cứu tiếp theo trong việc sản xuất các chế phẩm phòng và trị bệnh hoại tử gan tụy cấp tính trên tôm

PHÁT TRIỂN CHỈ THỊ PHÂN TỬ SCAR NHẬN DIỆN LOÀI Vibrio vulnificus GÂY BỆNH LỞ LOÉT TRÊN CÁ NUÔI TẠI TỈNH THỪA THIÊN HUẾ

Vibrio vulnificus is widespread on cultured fish with the ulcerative disease in the Thua Thien Hue province, Vietnam, and it is a potential human pathogen that can cause primary septicemia, wound infection, and gastroenteritis in susceptible individuals. Thus, this study is conducted to develop a molecular marker generated from random amplified polymorphic DNA (RAPD) for the rapid detection of V. vulnificus. Twenty random primers were tested by using the RAPD method to detect DNA polymorphisms among Vibrio species. The random primer OPA-09 generates a 1356-bp DNA fragment specific for V. vulnificus. This sequence was used to design a specific primer, and it was transferred to a sequence-characterized amplified region (SCAR) marker with a length of 938 bp (A9-938). The specific primers Vvul-1F/Vvul-938R amplify a unique DNA fragment in all isolates of V. vulnificus but not in the other tested Vibrio species. This marker is highly specific and can be used to identify the presence of V. vulnificus in seafood.Trong nghiên cứu trước đây, chúng tôi nhận thấy vi khuẩn Vibrio vulnificus khá phổ biến trên cá nuôi bị xuất huyết ở tỉnh Thừa Thiên Huế. Vi khuẩn này là một mầm bệnh cơ hội trên người, có thể gây nhiễm trùng máu nguyên phát, nhiễm trùng vết thương và viêm dạ dày, ruột. Vì vậy, chúng tôi thực hiện nghiên cứu nhằm phát triển một chỉ thị phân tử dựa trên kỹ thuật đa hình các đoạn khuếch đại ngẫu nhiên (RAPD) để xác định nhanh chóng V. vulnificus. Tổng cộng có 20 mồi ngẫu nhiên đã được sử dụng cho phản ứng PCR-RAPD để phát hiện đa hình DNA giữa các loài Vibrio. Trong đó, mồi OPA-09 tạo ra một sản phẩm khuếch đại đặc hiệu cho loài V. vulnificus có chiều dài là 1356 bp. Trình tự này được thiết kế mồi đặc hiệu và chuyển thành chỉ thị SCAR có chiều dài 938 bp (A9-938). Cặp mồi đặc hiệu (Vvul-1F/Vvul-938R) khếch đại một băng duy nhất ở tất cả các chủng V. vulnificus nhưng không xuất hiện ở các loài Vibrio khác. Đây là chỉ thị có độ đặc hiệu cao và có thể sử dụng để nhận diện sự có mặt của V. vulnificus có trong các mẫu hải sản