Vol. 20 No. 2 (2022)

Aviannephritis is an infectious diseases induced by several viruses, such as Infectious bronchitis virus (IBV) and Avian nephritis virus(ANV). In Vietnam, uric acid nephropathy found in sick chickens is commonly assigned as an infectious bronchitis virus-nephrosis form. In this report, RT-PCR method was applied for ANV detection. The presence of ANV was confirmed in a sick chick having nephritis with urate deposition in the absence of IBV infection. By genetic comparision of ORF1a sequences with the length of 447 nucleotides, the G19.24.2 virus strain were 95.30% similarity with a well characterized ANV/CHN/BJCP510-2/2018 strain (GenBank accession MN732558) detected in China in 2018. By phylogenetic classification, the ANV strain detected in this study was grouped with genotype 7 of ANV.

The purposes of this study were to investigate duck circovirus infection and characterize some duck circovirus strains from ducks in Ha Noi. A total of 31 pool tissue samples including brain, heart, liver, spleen, lung, and the bursa of Fabricius, were collected from duck flocks farmed in Thuong Tin, Ung Hoa, and Phu Xuyen districts during April to June of 2021. All samples were collected from clinically suspected focks and diseased ducks. Polymerase chain reaction was used to detect the viral genome. The positive samples were forwarded to sequencing the partial open reading frame 1. The viral genome was detected in 22 out of 31 (70.97%) samples. Of the 7 duck farms examined, 6 flocks (85.71%) were positive for the viral genome. Genetic analysis indicated that nucleotide identity ranged from 99.48% to 99.87% among the three viral strains in this study. Phylogenetic analysis revealed that the three viral strains obtained belonged to genotype 1 and genetically related to the Chinese strains.

PACAP được biểu hiện nhiều ở các nhân khác nhau ở vùng dưới đồi và có chức năng giúp kiểm soát sự thèm ăn. Gần đây, chúng tôi đã phát hiện ra neuropeptide PACAP làm tăng cảm giác thèm ăn ở chuột. Nhằm làm rõ hơn vai trò của tế bào thần kinh PACAP, trong nghiên cứu này, đã sử dụng phương pháp hóa sinh với thụ thể thiết kế được kích hoạt chọn lọc bằng hệ thống DREADDs và kiểm tra sự kết nối qua synap của các tế bào thần kinh bởi các vector biểu hiện synapsin. Kết quả chỉ ra việc kích hoạt hay ức chế có chọn lọc các tế bào thần kinh PACAP bởi DREADDs trong VMH, làm tăng hoặc giảm đáng kể lượng thức ăn thu nhận. Ngoài ra, nghiên cứu này chỉ ra sự kết nối giữa tế bào thần kinh PACAP trong VMH với tế bào thần kinh AgRP ở vùng Arc. Những kết quả này cho thấy tăng thu nhận thức ăn do gia tăng biểu hiện PACAP trong VMH thông qua điều chỉnh biểu hiện AgRP và ức chế PACAP hoặc AgRP là ứng dụng lâm sàng quan trọng trong giám sát béo phì.

The respiratory disease complex has emerged as a major economic problem for the poultry industry. In addition, the current diagnostic tools, such as bacteria isolation,serological tests, andconventional PCRare time-consuming and labor-intensive. Therefore, this study was carried out to develop the direct PCR and to apply it to investigate the presence of some common bacteria in the swollen head syndrome. Comparedwith the conventionalPCR results, the Kappavaluefor direct PCR was almost in perfect agreement. Among 173samples screening by direct PCR, 68% of cases revealed infection by atleastoneinvestigatedpathogen, while 23% had concurrent infections by two to three bacteriain a single case. As a result, direct PCR is recommended to be an effective tool for detecting the concurrent infections by Mycoplasma gallisepticum (MG), Avibacterium paragallinarum (APG), Ornithobacterium rhinotracheale (ORT)andavian pathogenicEscherichia coli (APEC)of the swollen head syndrome in chickens in the vicinity of Hanoi.

Short beak and dwarfism syndrome (Derzsy’s disease) is a serious concern for Asian countries,which was a significant cause of economic loss in waterfowl farming. The present studyaimed to provide clinical and pathological features on outbreak of Derzsy’s disease in commercial flock of 2 to 6-week-olds domestic ducks in BacGiang, Thai Nguyen and Hung Yen. Inthe present study, domestic ducks were observed for clinical symptoms, and necropsy samples were collected for a histopathological specimen examination. Clinical signs consisted mainly of anorẽia, growth retardation, short beak, nasaldischarge, and the shortening of the leg bones. Necropsy of thirty ducks revealed hydropericardium, hemorrhage myocardium or fibrinous exudate on the surface of the heartand liver. The wall of small intestine was slightly thinner. Histopathological examination showed typical cardiac lesions with degeneration of muscle fibers, thickened epicardium, expansion of the epicardium by clear spaces (edema) and loose infiltrate of inflammatory cells. In small intestine, the predominant lesions were degeneration and necrosis of epithelial cells (enterocytes). The infiltrated lymphocytes were strongly positive for CD3. Intranuclear inclusion body scattered found in the degenerated crypt of Lieberkuhn and/or the damaged epithelium cells.

A comparative study was conducted to evaluate the effectiveness of anesthetic methods in surgical surgery on catsat the Veterinary Hoaspital, Vietnam National University of Agriculture. A total of 20 selected experimental cats were devided into two groups, in which 10 cats were inhalative anesthetized using isoflurane (2-3% starting doseand maintain at 1-2% throughout surgery);and 10were anesthetized using intravenous injection with Zoletil 50 (13 mg/kg P). The results showed that inhalative anesthesia produced more stablize status of cats during surgery in term of body temperature, heart rate and blood pressure. In addition, the blood oxygen concentration of the inhalative group fluctuated between 93-95% and significantly higher than injection method. Moreover, cats in inhalative anesthesia group shows minor pain reflexes after surgery and 80% of cat have no hysterical reaction. On the other hand, disturbance were observed in 70% of cats in injection anesthesia group. Thus, inhalative anesthesia using Isoflurane is stable, safe and may become the prefered method for feline surgical anesthesia.

The present paper reported the incidence of ear mite infestation caused by Otodectes cynotisin dogs examined at the Veterinary Hospital of Vietnam National University of Agriculture. The dog earwax was examined under microscope to determine mite infestation status. The mite-infected dogs were divided in two groups and treated experimentally with Dexoryl and Frontline Plus. Examination of ear wax samples using microscopics showed that the incidence of ear mite infestation caused by Otodectes cynotiswas 31.03%. In O. cynotisinfected dogs, the group aged 0 - 6 months infected with the highest rate, accounting for 46.97%. Foreign dogs were infected with the rate of 38.41%, higher than those of local dogs, 20.21%. According to style of living, free range dogs were infected with the highest rate, 57.89%. Dexoryl and Frontline Plus were both effective in the treatment of otodectes ear mite infestation in dogs with 96.55% and 100%, respectively.

This study aimed to isolate and identify by PCR and MALDI-TOF MS of Riemerella anatipestifer(RA) strains isolated from ducks and muscovy ducks in Ha Nam province. Samples including brain, heart, liver, lung, and spleen were collected from 45 suspected ducks in the farms in Ly Nhan, Binh Luc, Duy Tien districts. Total 27 out of 45 ducks showed the appearance of suspected colonies with the following characteristics: small, transparent, non-hemolysis with the main biochemical features as negative for indole, positive for catalase and oxidase test, and did not grow on MacConkey agar plates. Rapid identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) showed that 27 suspected colonies were positive to RA. This result is 100% in agreement with the PCR results.

This study was conducted to evaluate the effects of dietaryfructooligosaccharides(FOS) and Bacillus subtilison immune response and disease resistance of red tilapia (Oreochromissp.). The experiment was randomly designed with 4 triplicated treatments including control; B.subtilis(107CFU/g); B.subtilis(107CFU/g)and 0,2% FOS; B.subtilis(107CFU/g)and 0,5% FOS. The samples were collected at the 2ndand 4thweek post-feeding and the 3rdday post challenge with Streptococcus agalactiae. The resultsafter 4 weeks of experiment showed that the total erythrocytes, leukocytes, monocytes, neutrophils, lymphocytes and lysozyme activity significantly increased (P <0.05) in treatmentsofB.subtilisand FOS supplementation in comparison tothe control treatment. After infection with S.agalactiae, a cumulative mortality of fish in treatments ofB.subtilisand FOS wassignificantly lower than thatof fish in the control treatment(P <0.05). In particular, the mortality ofB.subtilis107CFU/g + 0,5% FOS treatment was lowest (26.7%± 8.2%) and significantly differentwith other treatments(60 ± 6.7% và 46.7 ± 12.3%).The results indicated that the supplemented FOS and B.subtilisin the diet could stimulate the non-specific immune system of red tilapia and protect the fish from S.agalactiaeinfection.

The objective of this study was to assess the effect of nutrient concentration on zooplankton distribution in the aquaculture area of Soc Trang province. A total of 4 sampling times was conducted from March to December 2019. At each sampling time, the nutrient parameters and qualitative and quantitative data of zooplankton were collected at 10 locations in the aquaculture zones. The results showed that species composition of zooplankton in the rainy season was higher than that in the dry season. The highest zooplankton abundance was recorded at stations in the tributary, in which protozoa was the most dominant class in most sampling stations. The contents of total suspended solids (TSS), total nitrogen (TN), phosphate (PO43-) and total phosphorus (TP) were not closely correlated with the composition of zooplankton. However, the nitrate (NO3-) concentration was positively correlated (P <0.05) with the component and abundance of Rotifera, Cladoceraand Copepoda. The results of the study could be the basic data source to support the management of surface water resources and the sustainable development of brackish aquaculture in Soc Trang province.

This study was conducted to investigate the effects of β-glucan and probiotics supplementation on the survival rate and disease resistance of tilapia (O. niloticus) juverniles. The experiment was set up with four treatments consisting of the control treatment (ĐC), the mixture of beneficial microorganisms (NT1), the mixture of β-glucan (NT2) and 50% NT1 + 50% NT2 in NT3 and was replicated thrice. Fish were randomly stocked in 12 units of 8.0 m3(2 × 4 ×1m) cement tank and fed the experimental diets for 30 days. Experimental fish were infected with bacteria S. agalactiae at109 CFU/kg of feed. Infectious bacteria were re-isolated, re-examined and the antibiogram tested after treatment to assess the disease resistance of experimental batches. The trial results showed that disease appeared later in fish fed the β-glucan supplemented diet with lower mortality rate, and higher recovery rate after medicinal treatment than those fed the probiotic and control diets.

This study evaluated the efficacy of nano-silver (NS) for treatment of disease caused by I.multifiliisin snakehead fish (Channa argus) both vitroand vivoexperiments. A series of NS concentrations (0, 0.1, 0.5, 1, and 1.5 ppm) was tested on the parasitic stage (Trophont) and reproductive stage (Tomont). In vitrotesting results showed that NS was effective in killing germs in both trophont and tomont stages. The pathogen mortality was highest at 1.5 ppm NS; after 12h the mortality rate was 95.45 and 98.15% for trophont and tomont, respectively. All snakehead fish (3g) in the 7-day in vivoexperiment died at treatments of 1.5, 1 and 0 ppm NS on the 1st, 1st, and 6thday, respectively. The survival of fish in the 0.1 and 0.5 ppm treatments was 63.3% and 33.3%, respectively, on the 7thday. Hence, the NS might have killing effects on trophont and tomont but also toxic effects on 3-g snakehead fish.

The objective of the study was to evaluate the hatching rate, the survival rate of fry, fingerling, juvenile and the growth rate for breeding. Experiment on hatching, nursering and rearing of two introduced common carp strains (Tata and Szavas P3) from Hungary to Vietnam was carried out from July 2019 to December 2020 at the National Freshwater Broodstock Center. The results showed that the hatching time was 61.8 and 62.2 hours for Tata and Szavas strain, respectively; the figure of the hatching rate was 91.5% and 93.3%, and the deformity rate was 1.2% and 1.3%, respectively. The survival rate of Tata fingerling was 62.5% and of Szavas P3 was 67.5%. The survival rate of juvenile Tata carp was 48.7%, Szarvas P3 carp was 53.3%. The absolute growth in length and weight of Tata carp was 6.8mm/day and 0.51 gam/day, Szarvas P3 was 6.5 mm/day and 0.49 gam/day. After 12 months of culture, the average weight and length of Tata carp was 1670.5 ± 10.2 g/fish and 50.2 ± 7.1 cm/fish, Szavas P3 carp was 1565.5 ± 10.2 g/fish and 49.3 ± 7.7 cm/fish, the feed conversion ratio values was 2.0 for Tata and 1.9 for Szavas P3 carp. The results of hatching, nursering and rearing showed that Tata carp and Szavas P3 carp can be used as genetic material for selection breeding .

The study was conducted to evaluate the effect of dietary fucoidan extracted from brown seaweed Sargassum swartziion growth, survival rate, feed conversion ratio (FCR), and disease resistance to Aeromonas veroniibacterium in Nile tilapia (Oreochromis niloticus) fingerlings. Fish (23.2 ± 2.7g) were fed the commercial feed (35%Pr) supplemented with fucoidan at various concentrations (0%, 0.05%, 0.1%, 0.5%) in triplicate for 6 weeks. The results have showed that fucoidan did not significantly affect (P >0.05) the growth, survival, and FCR during the feeding trial. At the end of nutritional trial, fish were infected with Aeromonas veroniiat dose of LD50 (7.82 ×104CFU/ml), fish were then monitored for 10 days, the mortality was daily recorded. After 10 days of challenge, the results showed that the survival rate was 76.6% and 80% for 0.1% and 0.5% fucoidan-fed fish, respectively, much higher than other groups (30% and 36.7% for Control and 0.05% fucoidan-fed fish, respectively) (P < 0.05). In conclusion, dietary fucoidan extracted from brown seaweed Sargassum swartziiat 0.1 and 0.5% enhanced the resistance of tilapia fingerlings against to Aeromonas veronii.

Porcine Epidemic Diarrhea (PED) is an acute infectious disease caused by the PED virus (PEDV) with high mortality, causing huge economic losses. The objective of our study was to assess the risk of PEDV cross-contamination between farms through the movement of pig herds. Therefore,the pig transportation network analysis method was applied at some slaughterhouses in the North. Summarized data of 128 farms indicated that of four slaughterhouses, SL2 was slaughterhouse with the highest number of farms transported to (76 farms), of which 30.3% were positive for PEDV. The results of the transportation network analysis showed that, in total, there were 132 nodes, 148 edges, and SL2 was the most central node with the highest value of degree centrality of 82. The percentage of PEDV positive farms in 7 cluster-edge ranged from 16.7 to 44%, in which cluster-edge SL1, SL2, SL3 had more nodes as well as a higher percentage of PEDV positive farms than other clusters. The risk of a farm infected with PEDV when exposed to SL1, SL2, SL3 was higher than 3.57, 2.17, and 3.24 times, respectively, when exposed to SL4.