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Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

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20223
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Subject: Veterinary Pathology × End date: 2022 × Start date: 2022 × Type: Thesis ×
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    ThesisItemOpen Access
    Pathomorphological and molecular detection of avian leukosis virus infection in chicken
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Tamuly, Nibedita; Dutta, Biswajit
    Avian Leukosis being a common neoplastic disease of the commercial poultry farm, causes significant economic losses to the farmers. The present study was undertaken to determine the status of the infection in the poultry population from 7 different locations in Kamrup district of Assam. During the period of study, twenty two (22) outbreaks of avian leucosis were recorded from seven (7) different locations of undivided Kamrup district of Assam. A total 243 numbers of post mortem was conducted from which 65 positive cases were reported on the basis of gross examination, histopathological alteration and molecular detection. The overall mortality percentage was recorded as 4.11%. Among different age groups maximum mortality was reported in adult birds above 20 weeks of age (7.36%). However few cases were also reported below 16 weeks of age. Breed/strain wise study revealed highest mortality was reported in BV-380(6.17%) followed by BV-300 (4.47%) which was further followed by Kamrupa (3.49%) and Daothigir (3.47%). Season wise occurrence of the infection was more during winter (4.86%) followed by pre-monsoon (4.11%) and post monsoon (3.68%). Clinically, affected birds did not exhibit any typical clinical signs, however some of the affected birds showed signs like anaemia with pale comb, emaciation with decrease growth rate and productivity and osteopetrosis. The gross pathological study gives a presumptive diagnosis of the diseases where prominent lesions were found in liver, spleen, kidney and heart. In all the cases hepatomegaly was most commonly seen. The affected liver also showed nodular, eucosis or diffuse form of lesions. Spleen, kidney and heart also showed enlargement, necrosis and the presence of nodular growth. Even though the bursal involvement could not be detected due to its rudimentary form in adult birds but in two cases the lesions in bursa was prominent. Microscopic alterations were severe in liver, spleen, kidney, heart and lung characterized diffuse infiltration of immature lymphoid cells, causing distortion of normal parenchyma. Molecular detection by targeting gp85 env gene produced amplification bands at 229 bp. The phylogenetic analysis of the resultant sequences showed 99-100% homology with the endogenous forms of isolates from China, USA and South Korea. Virus can be isolated on 6th day old embryo where replication of the virus was showed by severe hemorrhages and mortality 48-96 hours of post infection. In field condition presence of other neoplastic diseases like Marek’s disease produces similar lesions which complicates proper diagnosis of avian leucosis. In such situations differential diagnosis can be made on the basis of cell cytology, histopathology and Polymerase chain reaction. In histopathology Marek’s diseases affected tissue showed infiltration of pleomorphic cells and on molecular detection positive samples produced bands at 225bp. Myeloid form and erythroid forms were not found during the study. And the present study reveals that infective form of subgroup E of avian leucosis is circulating in the residential poultry population which might undergo mutation along with exogenous forms and create a more severe form of the disease.
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    ThesisItemOpen Access
    Pathomorphological and molecular studies of respiratory mannheimiosis in goats
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Mazumder, Amdedul Islam; Begum, Shameem Ara
    The present investigation was conducted to study the pathomorphological and molecular studies of respiratory Mannheimiosis in goats for a period of one year from March 2021 to February 2022. The materials for the present study were collected from various sources such as slaughter houses in and around Guwahati and from postmortem examinations carried out in the Department of Veterinary Pathology, College of Veterinary Science, A.A.U., Khanapara, Guwahati-22. Based on gross observation 30 lungs showing lesions of pneumonia were collected during post mortem examination. Twenty one lung samples showing pneumonic lesions were also collected from slaughter houses. For detailed bacteriological and pathological studies all of the 51 pneumonic lungs were chosen. A total of 43 isolates of bacteria were obtained in the present study out of which seven isolates were morphologically and biochemically positive for Mannheimia haemolytica (16.28%). Apart from this, other bacteria isolated were Pasteurella multocida (23.26%), E. coli (20.93%), Klebsiella spp. (18.60%), Staphylococcus spp. (13.95%) and Streptococcus spp. (6.98%). All the 7 isolates of Mannheimia haemolytica were screened for Lkt and 16s rRNA gene respectively. The Lkt gene with amplicon size 206 bp and the 16s rRNA gene with amplicon size 1500 bp was detected in all the 7 isolates of Mannheimia haemolytica. The Phylogenetic analysis of 16s rRNA gene of Mannheimia haemolytica isolated from goats in the present study showed percent identity above 97 percent with other strains of Mannheimia haemolytica present in the NCBI Gene Bank throughout the world. Different types of pneumonia associated with respiratory Mannheimiosis recorded during the present study were bronchophneumonia (37.25%), interstitial pneumonia (27.45%), haemorrhagic pneumonia (19.61%), suppurative pneumonia (11.76%), and fibrinous pneumonia (3.92%). Patchy areas of consolidation in the cranioventral portion of lungs were the most commonly observed gross lesion in bronchopneumonia. Microscopically, bronchopneumonia was characterized by neutrophils and mono-nuclear cell infiltration with presence of fibrin in the bronchi, bronchiole, alveolar lumen and pleura. Interstitial pneumonia cases were characterized by enlarged and rubbery lungs which do not collapse when the thorax is opened. The interlobular septa were distended with exudate. Microscopically, alveolar wall was thickened due to infiltration of polymorphonuclear cells and lined by cuboidal epithelial cells. Alveolar lumen was also filled with polymorphonuclear cells, macrophages and desquamated epithelial cells. Haemorrhagic pneumonia cases revealed multifocal, patchy to diffuse areas of haemorrhage throughout the lung surface. Microscopically, there was hemorrhage within the alveoli and inter alveolar septa with leukocytic infiltration in the bronchus. The wall of the bronchus also showed the inflammatory changes. Areas of emphysema were also observed. Gross pathological alterations observed in suppurative pneumonia were multiple focal abscess formation on lung surface. Presence of creamy suppuration could also be noticed in tracheal lumen. Microscopically, heavy infiltration of neutrophils could be seen in bronchial and alveolar lumen. In some cases necrotic mass admixed with bacterial colonies surrounded by thick connective tissue capsule were also recorded with infiltration of polymorphonuclear cells, mononuclear cells, plasma cells and macrophages. In fibrinous pneumonia, lungs were covered with stringy net like material. Excess serous fluid was present in the pleural and peritoneal cavities. In few cases the lungs was tightly adhered to the thoracic wall due to deposition of fibrin. The interlobular septa were prominent due to accumulation of fibrin. Microscopically, fibrinous pneumonia was characterized by the presence of intra alveolar fibrin in the form of “fibrin balls” within the alveolar spaces. The traditional ‘oat cells’ and necrotic macrophages were present inside the damaged alveoli.
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    ThesisItemOpen Access
    Pathology and molecular diagnosis of helicobacter infection in pig
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Dutta, Kongkon Jyoti; Tamuli, Sarojini Mahanta
    Helicobacter is a zoonotic bacterium that has been associated with gastritis and ulcearative lesion in the stomach of pig. Prevalence of Helicobacter infection in pig was determined from four districts of Assam during the period from July, 2021 to June, 2022. The prevalence of Helicobacter infection was found to be 39.9% and 45.67% by RUT and PCR test, respectively. The age wise prevalence of Helicobacter infection revealed highest in adult pigs 42.37% (RUT) and 48% (PCR) in comparison with piglet 23.07% (RUT) and 16.66% (PCR). Among different farms the highest prevalence was recorded in unorganized farms 45.53% (RUT) and 52.17% (PCR) in compared to organized farms 32.96% (RUT) and 37.10% (PCR). The presence of HLOs in different regions of the stomach by RUT was recorded as Parsoesophagea (1.48%), Cardia (2.95%), Fundus (15.27%), and Pylorus (20.27%). The maximum positivity was recorded in pylorus and fundus region with 20.27% and 15.27% respectively. The presence of HLOs in different grades of gastric macroscopic lesions was determined. The positivity of HLOs in different grades of gastric macroscopic lesions recorded as: 1+ (Early or mild) (28.12%), 2+ (Severe) (37.03%), and 3+ (more severe+ ulcers) (56.89%). The maximum positive RUT was detected in Grade 3+ (58.89%). HLOs were detected by brush cytology from the mucosal surface satined with Giemsa and Gram’s stain in 22.66% and 16.74% of the samples respectively. The gross lesions of gastritis were recorded in 203 (58%) stomachs out of 350 pig carcasses examined. The present investigation recorded early or mild gastric lesions (1+) in 31.53%, severe lesion (2+) in 39.90% and more severe lesions and ulceration (3+) in 28.57% of the stomach examined grossly. The recorded lesions were various grades of lesions as thickening of the gastric wall, corrugation of the gastric folds, congestion and haemorrhages, necrosis and sloughing of the gastric mucosa, erosions and ulceration in the parsoesophagea as well as glandular regions of the stomach. The frequency of various histopathological lesions in affected stomach were Hyperkeratosis (17.28%), Parakeratosis (14.81%), Epithelial hyperplasia (44.44%), Glandular degeneration (60.49%), Vacuolation of glandular epithelium (56.79%), Lymhoid follicle (62.96%), Inflamatory cell infiltration (Neutrophil (32.09%), Lymphocyte (45.67%), Eosinophil (23.45%), Macrophage (28.39), Plasma cell (25.92%), Sloughing & erosion (53.08%), Ulcer, Congestion and Haemorrhages (39.50%), Glandular abscess (9.87%), Fibrosis (4.93%), Metaplasia and Dysplasia (3.70%), and Detection of Helicobacter (9.87%). Ultrastructurally, Helicobacters with bacillary morphology, inflammatory cells on the gastric mucosa and biofilm formation by coccoid form of Helicobacters were detected. PCR analysis of the gastric samples showed the presence of Helicobacter spp in 37 (45.67%) and Helicobacter suis in 17 (20.98%) samples. PCR detection rate was found to be higher from the pylorus and fundic region and severe gastric lesions of the stomach. To study the zoonotic potential of Helicobacters, a total of 30 saliva samples from pig farmers were subjected for PCR out of which Helicobacter spp. was detected in 8 numbers of samples. Further, Helicobacter suis (2) and Helicobacter pylori (3). Phylogenetic analysis revealed that Helicobacter suis detected from pig handlers and pig stomach samples shares above 99% identity suggesting zoonotic transmissions of Helicobacters from pig to human.