Objective: The objective of this study was to estimate the heritability (h2 ), repeatability (r), and correlations (r yi yi ) in some traits of zootechnical interest in a population of New Zealand white rabbits of a tropical dry forest area. Materials and Methods: Three mating groups were formed, each one of 1 male and 70 females. The traits evaluated were littersize at birth (LB), born alive (BA), born dead (BD), litter weight born alive (LW), litter weight at weaning (LWW), weaning weight (WW), slaughter weight (SW), and carcass weight (CW). Weaning took place at 42 days, and the fattening phase lasted 60 ± 3 days. A descriptive statistical study was carried out on the study variables. Paternal heritability was esti mated (h2 f ) and maternal (h2 m), repeatability, rabbit index IC, and Pearsons correlations (r yi yi ) between traits. The descriptive statistics showed high variation for the BD traits. Results: The values of the productivity found were similar to those presented in studies around the world. h2 presented magnitudes between low and medium. h2 f ranged between 0.09 and 0.42 and between 0.11 and 0.45 for h2 m. In general, the values of h2 m were higher than the values of h2 f . The r valuesforthe traits LB, BA, LW, LWW, and SW presented low magnitude, while it was medium for WW and CW. From the values of r, IC was calculated for each of the rabbits, allowing their categorization, which will be used in future selection plans. r yi yi among the variables ranged from −0.01 to 0.860. They were generally positive and mostly not significant (p > 0.05); they took a magnitude from low to moderate, except for the correlation between LB and BA. Conclusion: The production of rabbits under tropical conditions is similar to other reports. The genetic parameters evaluated were medium-to-low, indicating a robust non-additive gene and/ or environmental effect. [J Adv Vet Anim Res 2021; 8(3.000): 471-478]

Objective: The objective of this study was to estimate the heritability (h2), repeatability (r), and correlations ( rˆyi yi) in some traits of zootechnical interest in a population of New Zealand white rabbits of a tropical dry forest area.  Materials and Methods: Three mating groups were formed, each one of 1 male and 70 females. The traits evaluated were litter size at birth (LB), born alive (BA), born dead (BD), litter weight born alive (LW), litter weight at weaning (LWW), weaning weight (WW), slaughter weight (SW), and carcass weight (CW). Weaning took place at 42 days, and the fattening phase lasted 60 ± 3 days. A descriptive statistical study was carried out on the study variables. Paternal heritability was esti­mated (h2f ) and maternal ( h2m), repeatability, rabbit index IC, and Pearson’s correlations ( rˆyi yi) between traits. The descriptive statistics showed high variation for the BD traits.  Results: The values of the productivity found were similar to those presented in studies around the world. h2 presented magnitudes between low and medium. h2f ranged between 0.09 and 0.42 and between 0.11 and 0.45 for  h2m. In general, the values of  h2m were higher than the values of h2f . The r values for the traits LB, BA, LW, LWW, and SW presented low magnitude, while it was medium for WW and CW. From the values of r, IC was calculated for each of the rabbits, allowing their categorization, which will be used in future selection plans.  rˆyi yi among the variables ranged from −0.01 to 0.860. They were generally positive and mostly not significant (p > 0.05); they took a magnitude from low to moderate, except for the correlation between LB and BA.  Conclusion: The production of rabbits under tropical conditions is similar to other reports. The genetic parameters evaluated were medium-to-low, indicating a robust non-additive gene and/ or environmental effect. J. Adv. Vet. Anim. Res., 8(3): 471-478, September 2021 http://doi.org/10.5455/javar.2021.h536

Objective: Rabbit viral hemorrhagic disease (VHD) is a transmittable and lethal viral illness of rabbits. In this study, genetic identification and genetic analysis of the rabbit hemorrhagic disease virus (RHDV) was made in three governorates in Egypt from 2014 to 2019. Materials and Methods: Livers from 18 freshly dead rabbits, which was guessed to be VHD epidemics in Egypt (Giza, Menofia, and Fayoum governorates) from 2014 to 2019, were examined for RHDV. The examination was based on the hemagglutination assay (HA) test against different mammalian (human O-type and sheep) and avian (chicken and pigeon) erythrocytes, reverse transcriptase-polymerase chain reaction (RT-PCR), and sequencing of the segment of VP60. Results: 33% of the examined samples virus titers were 5 log2 to 8 log2 hemagglutination of human O-type erythrocytes when compared to 28%, 11%, and 28% of sheep, chicken, and pigeon erythrocytes, respectively. Four RHDV isolates out of eight RT-PCR positives were sequenced and phylogenetically analyzed. Sequenced isolates were designed and submitted to GenBank with accession numbers MN904506, MN904507, MN904508, and MN904509. These four RHDV isolates were related to classic G3 (GI.1d/RHDV). Twelve amino acid differences were detected between the vaccine strain sequence (Giza-2006) and RHDV isolates. Amino acid differences at 416, 423, and 476 positions seem interesting as they changed polarity that could change the protein structure and affect host interaction. Conclusions: There is antigenic variation between circulating RHVD strains and the vaccinal strain. This may be the leading cause of vaccination failure and may increase the need to check out the vaccination program against RHVD. [J Adv Vet Anim Res 2021; 8(3.000): 396-403]

Objective: Rabbit viral hemorrhagic disease (VHD) is a transmittable and lethal viral illness of rabbits. In this study, genetic identification and genetic analysis of the rabbit hemorrhagic disease virus (RHDV) was made in three governorates in Egypt from 2014 to 2019.  Materials and Methods: Livers from 18 freshly dead rabbits, which was guessed to be VHD epidemics in Egypt (Giza, Menofia, and Fayoum governorates) from 2014 to 2019, were examined for RHDV. The examination was based on the hemagglutination assay (HA) test against different mammalian (human O-type and sheep) and avian (chicken and pigeon) erythrocytes, reverse transcriptase-polymerase chain reaction (RT-PCR), and sequencing of the segment of VP60.  Results: 33% of the examined samples’ virus titers were 5 log2 to 8 log2 hemagglutination of human O-type erythrocytes when compared to 28%, 11%, and 28% of sheep, chicken, and pigeon erythrocytes, respectively. Four RHDV isolates out of eight RT-PCR positives were sequenced and phylogenetically analyzed. Sequenced isolates were designed and submitted to GenBank with accession numbers MN904506, MN904507, MN904508, and MN904509. These four RHDV isolates were related to classic G3 (GI.1d/RHDV). Twelve amino acid differences were detected between the vaccine strain sequence (Giza-2006) and RHDV isolates. Amino acid differences at 416, 423, and 476 positions seem interesting as they changed polarity that could change the protein structure and affect host interaction.  Conclusions: There is antigenic variation between circulating RHVD strains and the vaccinal strain. This may be the leading cause of vaccination failure and may increase the need to check out the vaccination program against RHVD. J. Adv. Vet. Anim. Res., 8(3): 396-403, September 2021 http://doi.org/10.5455/javar.2021.h528

Objectives: The research was carried out on broilers to determine the efficacy of probiotics (Bacillus subtilis and Saccharomyces boulardii combined) supplementation on growth performances, nutrient retention (metabolizable energy, dry matter, and crude protein), and cecal microbiology (Bifidobacteria spp., Clostridium spp., and coliforms). Materials and Methods: A total of 160 broiler chicks (day-old) were selected and differentiated randomly into 4 groups (T0, T1, T2, and T3) (40 × 4) comprising 40 birds in every single group. The control group (T0) was fed commercial broiler feed only and the other three groups, referred to as treatment groups (T1, T2, and T3), were treated with 1 gm ciprofloxacin, 1 gm probiotic, and 1 gm probiotic plus 0.5 gm enzyme, respectively, in per liter of fresh dietary water 8 h daily for 7 days in each phase. Experimental trials were divided into 2 phases, the starter phase from day 0 to 21 and the finisher phase from day 22 to 35. Results: Bodyweight gain and nutrient retention in experimental broiler birds in treatment groups were significantly (p < 0.05) higher than the control group. Overall body weight gain and nutrient retention of broiler chicks in treatment groups T2 and T3 were better than T1. From day 22 to 35, cecal Clostridium and coliform bacterial load counts were significantly lower p < 0.01, p < 0.05, and p < 0.01, respectively, in T1, T2, and T3 treatments than T0. Overall, Clostridium and coliform bacterial counts in the birds of treatment group T2 were significantly lower (p < 0.05) than T0. Conclusion: The probiotics, in addition to enzyme supplementation, had suitable influence effects on growth performance of broilers, birds retention of nutrient, and microfloral count in birds cecum. [J Adv Vet Anim Res 2021; 8(4.000): 534-539]

Objectives: The research was carried out on broilers to determine the efficacy of probiotics (Bacillus subtilis and Saccharomyces boulardii combined) supplementation on growth perfor­mances, nutrient retention (metabolizable energy, dry matter, and crude protein), and cecal microbiology (Bifidobacteria spp., Clostridium spp., and coliforms).  Materials and Methods: A total of 160 broiler chicks (day-old) were selected and differentiated randomly into 4 groups (T0, T1, T2, and T3) (40 × 4) comprising 40 birds in every single group. The control group (T0) was fed commercial broiler feed only and the other three groups, referred to as treatment groups (T1, T2, and T3), were treated with 1 gm ciprofloxacin, 1 gm probiotic, and 1 gm probiotic plus 0.5 gm enzyme, respectively, in per liter of fresh dietary water 8 h daily for 7 days in each phase. Experimental trials were divided into 2 phases, the starter phase from day 0 to 21 and the finisher phase from day 22 to 35.  Results: Bodyweight gain and nutrient retention in experimental broiler birds in treatment groups were significantly (p < 0.05) higher than the control group. Overall body weight gain and nutrient retention of broiler chicks in treatment groups T2 and T3 were better than T1. From day 22 to 35, cecal Clostridium and coliform bacterial load counts were significantly lower p < 0.01, p < 0.05, and p < 0.01, respectively, in T1, T2, and T3 treatments than T0. Overall, Clostridium and coliform bacterial counts in the birds of treatment group T2 were significantly lower (p < 0.05) than T0.  Conclusion: The probiotics, in addition to enzyme supplementation, had suitable influence effects on growth performance of broilers, birds retention of nutrient, and microfloral count in birds’ cecum. J. Adv. Vet. Anim. Res., 8(4): 534-539, December 2021 http://doi.org/10.5455/javar.2021.h543

Objective: This research aims to study the target specificity of selective bioactive compounds in complexing with the human angiotensin-converting enzyme (hACE2) receptor to impede the severe acute respiratory syndrome coronavirus 2 influx mechanism resulting in cardiac injury and depending on the receptors active site properties and quantum tunneling. Materials and Methods: A library of 120 phytochemical ligands was prepared, from which 5 were selected considering their absorption, distribution, metabolism, and excretion (ADMET) and quantitative structureactivity relationship (QSAR) profiles. The protein active sites and belong¬ing quantum tunnels were defined to conduct supramolecular docking of the aforementioned ligands. The hydrogen bond formation and hydrophobic interactions between the ligandrecep¬tor complexes were studied following the molecular docking steps. A comprehensive molecular dynamic simulation (MDS) was conducted for each of the ligandreceptor complexes to figure out the values root mean square deviation (RMSD) (Å), root mean square fluctuation (RMSF) (Å), H-bonds, Cα, solvent accessible surface area (SASA) (Å2), molecular surface area (MolSA) (Å2), Rg (nm), and polar surface area (PSA) (Å). Finally, computational programming and algorithms were used to interpret the dynamic simulation outputs into their graphical quantitative forms. Results: ADMET and QSAR profiles revealed that the most active candidates from the library to be used were apigenin, isovitexin, piperolactam A, and quercetin as test ligands, whereas serpentine as the control. Based on the binding affinities of supramolecular docking and the parameters of molecular dynamic simulation, the strength of the test ligands can be classified as isovitexin > quercetin > piperolactam A > apigenin when complexed with the hACE2 receptor. Surprisingly, serpentine showed lower affinity (−8.6 kcal/mol) than that of isovitexin (−9.9 kcal/mol) and quer¬cetin (−8.9 kcal/mol). The MDS analysis revealed all ligands except isovitexin having a value lower than 2.5 Ǻ. All the test ligands exhibited acceptable fluctuation ranges of RMSD (Å), RMSF (Å), H-bonds, Cα, SASA (Å2), MolSA (Å2), Rg (nm), and PSA (Å) values. Conclusion: Considering each of the parameters of molecular optimization, docking, and dynamic simulation interventions, all of the test ligands can be suggested as potential targeted drugs in blocking the hACE2 receptor. [J Adv Vet Anim Res 2021; 8(4.000): 540-556]

Objective: This research aims to study the target specificity of selective bioactive compounds in complexing with the human angiotensin-converting enzyme (hACE2) receptor to impede the severe acute respiratory syndrome coronavirus 2 influx mechanism resulting in cardiac injury and depending on the receptor’s active site properties and quantum tunneling.  Materials and Methods: A library of 120 phytochemical ligands was prepared, from which 5 were selected considering their absorption, distribution, metabolism, and excretion (ADMET) and quantitative structure–activity relationship (QSAR) profiles. The protein active sites and belong­ing quantum tunnels were defined to conduct supramolecular docking of the aforementioned ligands. The hydrogen bond formation and hydrophobic interactions between the ligand–recep­tor complexes were studied following the molecular docking steps. A comprehensive molecular dynamic simulation (MDS) was conducted for each of the ligand–receptor complexes to figure out the values – root mean square deviation (RMSD) (Å), root mean square fluctuation (RMSF) (Å), H-bonds, Cα, solvent accessible surface area (SASA) (Å2), molecular surface area (MolSA) (Å2), Rg (nm), and polar surface area (PSA) (Å). Finally, computational programming and algorithms were used to interpret the dynamic simulation outputs into their graphical quantitative forms.  Results: ADMET and QSAR profiles revealed that the most active candidates from the library to be used were apigenin, isovitexin, piperolactam A, and quercetin as test ligands, whereas serpentine as the control. Based on the binding affinities of supramolecular docking and the parameters of molecular dynamic simulation, the strength of the test ligands can be classified as isovitexin > quercetin > piperolactam A > apigenin when complexed with the hACE2 receptor. Surprisingly, serpentine showed lower affinity (−8.6 kcal/mol) than that of isovitexin (−9.9 kcal/mol) and quer­cetin (−8.9 kcal/mol). The MDS analysis revealed all ligands except isovitexin having a value lower than 2.5 Ǻ. All the test ligands exhibited acceptable fluctuation ranges of RMSD (Å), RMSF (Å), H-bonds, Cα, SASA (Å2), MolSA (Å2), Rg (nm), and PSA (Å) values.  Conclusion: Considering each of the parameters of molecular optimization, docking, and dynamic simulation interventions, all of the test ligands can be suggested as potential targeted drugs in blocking the hACE2 receptor. J. Adv. Vet. Anim. Res., 8(4): 540-556, December 2021 http://doi.org/10.5455/javar.2021.h544

Objective: The case study describes the cause of an increase in mortality rates among 35-day-old broilers that developed respiratory distress and bloody diarrhea on a farm in Malaysia. Materials and Methods: The organ samples were subjected to laboratory testing and postmortem inspection. Escherichia (E.) coli and Mycoplasma (M.) gallisepticum were detected using bacterial isolation and molecular diagnostics using polymerase chain reaction. Results: Chickens with the infection had widespread fibrin buildup in several organs and hemorrhages on the duodenal mucosa. Additional histology and laboratory analysis of organ samples revealed infection with M. gallisepticum, E. coli, and enteric Eimeria spp., all of which are consistent with complex chronic respiratory disease (CCRD) associated with coccidiosis. Tylosin tartrate 20% (w/w) (2.5 gm/l) was prescribed for 1 week along with a combination of the broad-spectrum bacteriostatic drug streptomycin (25 mg/kg) and coccidiostat (2 gm/5 l). Conclusion: CCRD and coccidiosis are both infectious diseases that can infect chicken flocks, resulting in production losses and carcass quality degradation. Early disease detection and proper treatment should be provided promptly, and tight farm biosecurity should be implemented to prevent chicken mortality on the farm, as was achieved successfully. [J Adv Vet Anim Res 2021; 8(4.000): 576-580]

Objective: The case study describes the cause of an increase in mortality rates among 35-day-old broilers that developed respiratory distress and bloody diarrhea on a farm in Malaysia.  Materials and Methods: The organ samples were subjected to laboratory testing and postmor­tem inspection. Escherichia (E.) coli and Mycoplasma (M.) gallisepticum were detected using bac­terial isolation and molecular diagnostics using polymerase chain reaction.  Results: Chickens with the infection had widespread fibrin buildup in several organs and hemor­rhages on the duodenal mucosa. Additional histology and laboratory analysis of organ samples revealed infection with M. gallisepticum, E. coli, and enteric Eimeria spp., all of which are consis­tent with complex chronic respiratory disease (CCRD) associated with coccidiosis. Tylosin tartrate 20% (w/w) (2.5 gm/l) was prescribed for 1 week along with a combination of the broad-spectrum bacteriostatic drug streptomycin (25 mg/kg) and coccidiostat (2 gm/5 l).  Conclusion: CCRD and coccidiosis are both infectious diseases that can infect chicken flocks, resulting in production losses and carcass quality degradation. Early disease detection and proper treatment should be provided promptly, and tight farm biosecurity should be implemented to prevent chicken mortality on the farm, as was achieved successfully. J. Adv. Vet. Anim. Res., 8(4): 576-580, December 2021 http://doi.org/10.5455/javar.2021.h547

Objective: The purpose of this study was to determine the effects of the ethanolic extract of avocado seed flour on the estrous cycle characteristics, the concentrations of reproductive hormones [luteinizing hormone (LH) and estradiol], and the activities of some tissues (ovarian and uterine) that are markers of oxidative stress in female guinea pigs (Cavia porcellus). Materials and Methods: Twenty-four female cavies with normal estrous cycles and equivalent body weights (464.25 and 71.88 gm) were randomly assigned to four groups, each with six females. The control group received 1 ml of distilled water orally, whereas the EE100, EE200, and EE400 groups received 100, 200, and 400 mg/kg bw of ethanolic extract of Persea americana seed, respectively. Following that, three consecutive estrous cycles were observed using vaginal smears. After the trial, the females were slaughtered, and blood and organs were gathered for study. Results: The mean duration of the estrus phase is considerably (p < 0.05) longer in group EE100 animals than in control animals. LH concentrations were substantially (p < 0.05) higher in females in group EE200 than in controls. Total cholesterol levels typically dropped in females in the extract groups, but only significantly (p < 0.05) in those in group EE100 compared to the control group. Serum estradiol levels increased considerably (p < 0.05) in treated females compared to controls. Catalase activity rose considerably (p < 0.05) in the ovaries of group EE400 when compared to the control. Superoxide dismutase activity rose considerably (p < 0.05) in the uterus of female cavies given the extract compared to the control. Conclusion: Avocado seed ethanolic extract prolongs the estrus phase, increases estradiol and LH levels, and protects the uterus from oxidative stress in female cavies. [J Adv Vet Anim Res 2021; 8(3.000): 501-510]

Objective: The purpose of this study was to determine the effects of the ethanolic extract of avo­cado seed flour on the estrous cycle characteristics, the concentrations of reproductive hormones [luteinizing hormone (LH) and estradiol], and the activities of some tissues (ovarian and uterine) that are markers of oxidative stress in female guinea pigs (Cavia porcellus).  Materials and Methods: Twenty-four female cavies with normal estrous cycles and equivalent body weights (464.25 and 71.88 gm) were randomly assigned to four groups, each with six females. The control group received 1 ml of distilled water orally, whereas the EE100, EE200, and EE400 groups received 100, 200, and 400 mg/kg bw of ethanolic extract of Persea americana seed, respectively. Following that, three consecutive estrous cycles were observed using vaginal smears. After the trial, the females were slaughtered, and blood and organs were gathered for study.  Results: The mean duration of the estrus phase is considerably (p < 0.05) longer in group EE100 animals than in control animals. LH concentrations were substantially (p < 0.05) higher in females in group EE200 than in controls. Total cholesterol levels typically dropped in females in the extract groups, but only significantly (p < 0.05) in those in group EE100 compared to the control group. Serum estradiol levels increased considerably (p < 0.05) in treated females compared to controls. Catalase activity rose considerably (p < 0.05) in the ovaries of group EE400 when compared to the control. Superoxide dismutase activity rose considerably (p < 0.05) in the uterus of female cavies given the extract compared to the control.  Conclusion: Avocado seed ethanolic extract prolongs the estrus phase, increases estradiol and LH levels, and protects the uterus from oxidative stress in female cavies. J. Adv. Vet. Anim. Res., 8(3): 501-510, September 2021 http://doi.org/10.5455/javar.2021.h540

Objectives: The experiment was conducted to determine the effect of dietary energy and protein level growth performances of selected indigenous Ethiopian sheep breeds. Materials and Methods: Fifty intact ram lambs, 25 from each breed with 12 months of age and a mean initial body weight (IBW) of 19.31 ± 1.7 kg, were employed for this experiment. Animals were distributed randomly into five dietary treatments, i.e., minimum Energy and Protein (mEmP), medium energy and protein (MEMP), medium Energy and high Protein (MEHP), high energy and medium protein (HEMP), and high Energy and high Protein (HEHP) diets in randomized complete block design with 2 * 5 factorial arrangements. The minimum, medium, and high energy diets were 2.388, 2.866, and 3.344 Mcal/kg dry matter (DM) with the corresponding 10%, 16%, and 20% crude protein (CP) diets, respectively. The diets were formulated in a total mixed ration from wheat bran (WB), maize grain, peanut cake, and pasture hay feed ingredients. Diet offer was at the rate of 3% of lambs live weight and revised biweekly as per the attained body weight changes. Digestibility trial was conducted for 7 days of actual fecal data collection, followed by 90 days of feeding trial. Results: The animals fed on the MEHP diet had a maximum DM and nutrient intakes (CP and organic matter) and the best final body weight (FBW), total gain, gain rate, average daily gains, and feed conversion efficiency (31.3, 12.9 kg, 41.2%, 143.3 gm, and 23.13, respectively), followed by HEMP, HEHP, MEMP, and mEmP diets. Digestibility of DM and nutrients linearly followed similar trends (p < 0.01). Hararghe sheep was heavier (p < 0.01) by 4.3 and 3.1 kg in its FBW and total gain and more efficient in nutrients utilization (22.57 vs. 18.18) as compared to Afar sheep (AS). Conclusion: It is concluded that MEHP and MEMP are superior and optimum diets for sheep breeds, and Hararghe sheep is carried out better than AS in most growth performance parameters. [J Adv Vet Anim Res 2021; 8(2.000): 185-194]

Objectives: The experiment was conducted to determine the effect of dietary energy and protein level growth performances of selected indigenous Ethiopian sheep breeds.  Materials and Methods: Fifty intact ram lambs, 25 from each breed with 12 months of age and a mean initial body weight (IBW) of 19.31 ± 1.7 kg, were employed for this experiment. Animals were distributed randomly into five dietary treatments, i.e., minimum Energy and Protein (mEmP), medium energy and protein (MEMP), medium Energy and high Protein (MEHP), high energy and medium protein (HEMP), and high Energy and high Protein (HEHP) diets in randomized complete block design with 2 * 5 factorial arrangements. The minimum, medium, and high energy diets were 2.388, 2.866, and 3.344 Mcal/kg dry matter (DM) with the corresponding 10%, 16%, and 20% crude protein (CP) diets, respectively. The diets were formulated in a total mixed ration from wheat bran (WB), maize grain, peanut cake, and pasture hay feed ingredients. Diet offer was at the rate of 3% of lambs’ live weight and revised biweekly as per the attained body weight changes. Digestibility trial was conducted for 7 days of actual fecal data collection, followed by 90 days of feeding trial.  Results: The animals fed on the MEHP diet had a maximum DM and nutrient intakes (CP and organic matter) and the best final body weight (FBW), total gain, gain rate, average daily gains, and feed conversion efficiency (31.3, 12.9 kg, 41.2%, 143.3 gm, and 23.13, respectively), followed by HEMP, HEHP, MEMP, and mEmP diets. Digestibility of DM and nutrients linearly followed similar trends (p < 0.01). Hararghe sheep was heavier (p < 0.01) by 4.3 and 3.1 kg in its FBW and total gain and more efficient in nutrients utilization (22.57 vs. 18.18) as compared to Afar sheep (AS).  Conclusion: It is concluded that MEHP and MEMP are superior and optimum diets for sheep breeds, and Hararghe sheep is carried out better than AS in most growth performance parameters. J. Adv. Vet. Anim. Res., 8(2): 185-194, June 2021

Objective: Present research aims to isolate, identify, and determine the virulence of the Streptococcus agalactiae (group B Streptococcus; GBS), isolated from popped eye disease affected Tilapia and Vietnamese Koi (V. Koi) fishes. Materials and Methods: A total of 330 fish samples were collected, of which Tilapia (n = 180) and V. Koi (n = 150), were collected from 35 affected ponds of four selected districts of Bangladesh. Isolation of the bacterium was done using different culture media (Nutrient broth, Plate count agar, Tryptic Soy Agar, and Blood agar), and identification by using various biochemical tests (con¬ventional and using API 20 Strep kit) and polymerase chain reaction (PCR) using primers against 16S rRNA gene of S. agalactiae. Antibiotic susceptibility of the bacteria was performed using seven different antibiotics disc (Tetracycline, Oxytetracycline, Chlortetracycline, Streptomycin, Ciprofloxacin, Gentamicin, and Neomycin). Virulence of the isolated S. agalactiae was determined by infecting healthy Tilapia and V. Koi fishes through experimental infection. Results: Isolated bacteria were found Gram-positive paired and chained cocci, β-hemolytic and non-motile. Findings of biochemical and serological tests indicate that the isolated bacterium belongs to Group B Streptococcus of Lancefield classification. PCR result also confirmed that the bacteria were S. agalactiae. The bacterial isolates possessed resistance property against all the seven antibiotics used in this study. The isolated GBS was found highly virulent and showed 80%90% mortality for Tilapia and V. Koi fishes in experimental infection within 16 days of post-infection. Conclusion: From the findings of this study, it may be concluded that isolated GBS from the Tilapia and V. Koi fishes were highly virulent and possessed multidrug-resistance properties. [J Adv Vet Anim Res 2021; 8(1.000): 14-23]

Objective: Present research aims to isolate, identify, and determine the virulence of the Streptococcus agalactiae (group B Streptococcus; GBS), isolated from popped eye disease affected Tilapia and Vietnamese Koi (V. Koi) fishes.  Materials and Methods: A total of 330 fish samples were collected, of which Tilapia (n = 180) and V. Koi (n = 150), were collected from 35 affected ponds of four selected districts of Bangladesh. Isolation of the bacterium was done using different culture media (Nutrient broth, Plate count agar, Tryptic Soy Agar, and Blood agar), and identification by using various biochemical tests (con­ventional and using API 20 Strep kit) and polymerase chain reaction (PCR) using primers against 16S rRNA gene of S. agalactiae. Antibiotic susceptibility of the bacteria was performed using seven different antibiotics disc (Tetracycline, Oxytetracycline, Chlortetracycline, Streptomycin, Ciprofloxacin, Gentamicin, and Neomycin). Virulence of the isolated S. agalactiae was determined by infecting healthy Tilapia and V. Koi fishes through experimental infection.  Results: Isolated bacteria were found Gram-positive paired and chained cocci, β-hemolytic and non-motile. Findings of biochemical and serological tests indicate that the isolated bacterium belongs to Group B Streptococcus of Lancefield classification. PCR result also confirmed that the bacteria were S. agalactiae. The bacterial isolates possessed resistance property against all the seven antibiotics used in this study. The isolated GBS was found highly virulent and showed 80%–90% mortality for Tilapia and V. Koi fishes in experimental infection within 1–6 days of post-infection.  Conclusion: From the findings of this study, it may be concluded that isolated GBS from the Tilapia and V. Koi fishes were highly virulent and possessed multidrug-resistance properties. J. Adv. Vet. Anim. Res., 8(1): 14-23, Mar 2021 http://doi.org/10.5455/javar.2021.h480