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2019 - 20204
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Subject: Aquaculture × Start date: 2019 × Thesis Type: M.F.Sc ×
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    ThesisItemOpen Access
    CHARACTERIZATION AND ANTIMICROBIAL RESISTANCE OF AEROMONAS SPECIES ISOLATED FROM CULTURED FRESHWATER FISHES
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2020-12) SRUTHI, PERLA; Neeraja, T (MAJOR); Haribabu, P; Balasubramanian, A
    Pathogenic Aeromonas species are causing significantly high mortalities and economic losses among the cultured freshwater fish in India and Andhra Pradesh. The aim of the present study was to identify the Aeromonas species isolated from cultured freshwater fishes majorly exhibiting bacterial haemorrhagic septicaemia, abdominal dropsy, tail rot and fin rot in two districts viz., West Godavari and SPSR Nellore districts of Andhra Pradesh, India. The diseased fish species collected from farms were Catla catla (catla), Labeo rohita (rohu), Piaractus brachypomus (pacu) and Pangasius hypophthalmus (pangas). Further, the resistance of the isolated Aeromonas spp. to the currently available antimicrobial therapeutics was determined. In the present study, 15 species of Aeromonas were isolated viz., Aeromonas allosacharrophila (n=3), A. aquariorum (n=2), A. caviae (n=1), A. enchelia (n=1), A. jandaei (n=3), A. media (n=2), A. molluscorum (n=3), A. piscicola (n=1), A. popoffii (n=3), A. sobria (n=3), A. schubertii (n=6), A. tecta (n=9), A. trota (n=3), A. veronii biovar sobria (n=5) and A. veronii biovar veronii (n=13). The Aeromonas species isolated on RS medium and GSPA medium were identified and characterized by conventional biochemical tests. The study on prevalence of Aeromonas spp. was carried out for a period of 7 months from September 2019 to March 2020 in the above two districts revealed that the highest prevalence was recorded in A. veronii bv. veronii. Significantly higher prevalence (P 0.05) with the latter species. Further, prevalence of Aeromonas spp. were significantly different (p <0.05) with respect to fish species and geographic location. In vitro antibiotic resistance study revealed that all the isolates of 15 Aeromonas spp. were highly resistant to ampicillin, amoxyclav and oxytetracycline. Further, all the Aeromonas spp. were found multiple antibiotic resistance (MAR). The MAR index of more than 0.2 was observed in all the isolates of Aeromonas spp. except A. piscicola. It indicates that these Aeromonas spp. might have originated from high risk sources of contamination. Haemolytic activity assay revealed that A. veronii bv. sobria (60%), A. aquariorum (50%), A. jandaei (33.3%), A. sobria (33.3%) and A. tecta (22.22%) were found to be β-haemolytic. However, majority of the Aeromonas spp. isolates were found α- haemolytic.
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    ThesisItemOpen Access
    SURVEILLANCE ON BACTERIAL DISEASES OF CULTURED INDIAN MAJOR CARPS IN ANDHRA PRADESH, INDIA
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2020-06) SRIVIDYA, R; Neeraja, T(MAJOR); Haribabu, P; Dhanapal, K
    Bacterial fish diseases were considered to be the main cause of high mortalities and economic losses among the cultured freshwater fish in Andhra Pradesh. The aim of the present study was to identify the bacterial strains isolated from farm raised Indian major carps majorly exhibiting bacterial haemorrhagic septicaemia, abdominal dropsy, tail rot and fin rot in two districts viz., SPSR Nellore and West Godavari districts of Andhra Pradesh, India. Further, the susceptibility of the isolated bacterial strains to the currently available antimicrobial therapeutics was determined. In the present study, the pathogenic bacteria isolated were species of Aeromonas, Pseudomonas and Enterobacteriacea family. 7 species of Aeromonas viz., Aeromonas hydrophila, A. tecta, A. caviea, A. sobria, A. veronii A. schubertii and A. encheleia; 4 species of Pseudomonas viz., Pseudomonas sp., Pseudomonas stutzeri, P. diminuta and P. fluoroscenes; 5 species of Enterobacteriacea family viz., Citrobacter freundi, Serratia rubidaea, S. fonticola, Klebsiella pneumoniae ssp pneumniae and Enterobacteriacea group were identified and characterized by conventional biochemical tests. The prevalence study carried out for a period of one year from July 2018 to June 2019 in the above two districts revealed the dominance of aeromoniasis caused by Aeromonas spp. Significantly higher prevalence (P 0.05) with that of aeromoniasis. Further, prevalence of bacterial diseases did not vary significantly (P > 0.05) with respect to fish species, geographic location and seasonality. In vitro antibiotic sensitivity study revealed that gentamicin, ciprofloxacin, amikacin and trimethoprim were found to be more effective against Aeromonas sp., Pseudomonas sp. and Enterobacteriaceae family. Multiple antibiotic resistance (MAR) study showed that all the species of Pseudomonas and Enterobacteriaceae family were MAR. Among Aeromonas sp., A. tecta and A. caviea were 100% MAR, however 80% of A. sobria, A. veronii and A. schubertii showed MAR and 50% of A. hydrophila strains only showed MAR. The MAR index of more than 0.2 was observed in all the bacterial strains of Aeromonas, Pseudomonas and Enterobacteriaceae family indicated that these bacterial strains might have originated from high risk sources of contamination. Haemolytic activity assay revealed that A. veronii (80%), A. schubertii, (60%), A. sobria (40%) and A. tecta (33.3%) were found to be β-haemolytic.
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    ThesisItemOpen Access
    EFFECT OF DIETARY TRYPTOPHAN SUPPLEMENTATION ON CANNIBALISM, SURVIVAL AND GROWTH OF JUVENILE STRIPED MURREL, CHANNA STRIATA
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2019-11) CHINNARI, M; CHANDRASEKHARARAO, A (MAJOR); RAVINDRAKUMARREDDY, D; MADHAVI, K
    The present study “Effect of dietary tryptophan supplementation on cannibalism, survival and growth of juvenile striped murrel, Channa striata” was conducted in the Wet Laboratory of the Department of Aquaculture, College of Fishery Science, Sri Venkateswara Veterinary University, Muthukur, Nellore Dist. A 63 day feeding trail was conducted to evaluate the effect of different dietary tryptophan supplementation on growth, SGR, FCR, survival and cannibalism in C. striata juveniles. Two hundred and twenty five juveniles were distributed into 5 treatment groups (200 lit tank, 15fish per tank and 0.90 gm in body weight and 3.00 cm in total length). Each treatment group in triplicate setup was fed with a diet containing either 0% (T1), 0.25% (T2), 0.75% (T3), 1% (T4) L- Tryptophan supplementation in the diet. Results obtained in the weekly sampling were subjected to statistical analysis. The water quality parameters recorded were with the optimal range for fish culture. Tryptophan supplemented diets were effective in the reducing the aggressive behavior in juveniles resulted in reduction of cannibalism in treatment diets than in Control. Lowest cannibalism was recorded in the T3 (2.3±0.451) and T4 (2.3± 0.351). The highest survival rate (77.7%) was noticed in the T3 treatment and the lowest was in Control. Growth enhancement was also obtained in the tryptophan supplementations diet treatments. At the end of experiment period, the highest average body weight of 8.15gm (T3 – 0.75% TRP) and the lowest average body weight of 6.49 gm (C – 0.0% TRP) was observed among all varied tryptophan percentage supplementation treatments. The highest weight gain of 7.23 gm was observed in T3 animals and lowest 5.56 gm in Control. The lowest FCR values of 1.59 better suited for culture of juvenile C. striata was found in T3 diet among all experimental diets. In all the tryptophan supplementation treatments the highest SGR (3.45%) was observed in T3 and the lowest recorded for Control (3.07%).
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    ThesisItemOpen Access
    STUDY OF CHANGES IN THE VIBRIO COMMUNITIES IN POND WATER DURING WHITE SHRIMP (PENAEUS VANNAMEI) CULTIVATION AND IN THE HEPATOPANCREAS OF HEALTHY AND DISEASED SHRIMP
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2019-11) ASHOK KUMAR, B; Hari Babu, P (MAJOR); Neeraja, T; Madhavan, N
    Pacific white shrimp (Litopenaeus vannamei) is one of the most important cultivated shrimp species worldwide. However threat of various diseases is one of the biggest risk factors for healthy and sustainable development in shrimp aquaculture. Vibriosis mainly caused by Vibrio harveyi, Vibrio parahaemolyticus and Vibrio alginolyticus is the most prevalent bacterial disease in global shrimp farming. Healthy and infected/moribund shrimp samples were collected from three ponds in Nellore region of Andhra Pradesh from January, 2019 to March 2019. Vibrio spp. were isolated from the pond water and the hepatopancreas of healthy and infected/moribund shrimp using (TCBS) thiosulfate–citrate–bile salt–sucrose agar plate, and then identified by conventional biochemical tests. The dominant Vibrio type in healthy shrimp hepatopancreas were V. alginolyticus (41.6%), followed by V. damsela (25%), V. vulnificus (16.6%), V. mimicus (8.3%), V. anguillarium (4.1%) and V. ordali (5.5%). The concentration of Vibrios load in healthy shrimp hepatopancreas was ranged from 6.5×103-9.7×103 CFU/gm. Whereas seven types of Vibrio such as V. parahaemolyticus (45.8%), followed by V. harveyi (16.6%) and V. vulnificus (12.5%), V. anguillarium (8.3%), V. ordali (8.3%), V. mimicus (8.3%) and V. damsela (4.1%) were predominant in the hepatopancreas of infected/moribund shrimp samples. Vibrio load in infected shrimp hepatopancrease was ranged from 7.8×103 -10.5×103 CFU/gm. Total of six distinct Vibrio species such as V. parahaemolyticus (41.6%), V. alginolyticus (20.8%), V. harveyi (12.5%), V. mimicus (12.5%), V. ordali (8.3%) and V. anguillarium (4.16%) were identified from water samples. The number of Vibrio was ranged from 4.8×103_ 7.5×103 CFU/ml in water samples. Severe stress and injury to shrimp under poor environmental conditions lower their resistance, rendering them susceptible to opportunistic pathogens. Influence of turbidity, heavy organic matter plays a major role in the distribution of bacterial population in pond water. The present study showed that similar pond management and environmental parameters influenced Vibrio species composition in water both qualitatively and quantitatively. However healthy and infected (moribund) shrimp showing variation in occurrence of Vibrio at the time of sampling. This indicates, the healthy shrimp shows the selectively avoiding the pathogenic vibrios. At the same time the pond water is showing decrease in species diversity at 60 DOC. Similar observation was made by HH Sung et al (2001). In India there are nearly 80,000 shrimp farmers depended on shrimp farming and majority of these are small and marginal farmers. This study is aimed at educating these small and marginal farmers on Vibrio species dynamics at pond level so that the farmers can avoid misuse of antibiotics instead they depend on better management practices.