• Korean Journal of Veterinary Service
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• v.43 no.4
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• pp.257-259
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• 2020

Ornithobacterium rhinotracheale (ORT) causes pneumonia, airsacculitis, and pleuritis in chickens and other avian species. Little is known about the seroprevalence of ORT in layer chickens in Gyeonggi province, South Korea. The purpose of this study was to determine the seroprevalence of ORT in layer chickens in Gyeonggi province, South Korea from May to September 2019. A total of 460 chickens in 28 flocks were tested for antibodies to ORT by using commercial enzyme-linked immunosorbent assay (ELISA) kit. The seroprevalence of ORT antibodies in the flocks was 100% (28/28) and the overall seroprevalence in individual chickens was 98.91% (455/460). This survey indicated the high seroprevalence of ORT in layer chickens in Gyeonggi province, South Korea. Therefore, measures should be executed to control ORT in layer chickens in this province.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.811-817
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• 1998

Humoral and cellular immune responses are depressed in chickens infected with reticuloendotheliosis virus(REV). The extent of depression is influenced by the age of infection and strain of virus. This study was conducted for investigation of immunosuppressive effects of a Korean isolate of REV. Chickens infected with REV-HI, a Korean isolate, at 1 day old were severely suppressed in the vaccinal immunity against Newcastle disease, infectious bronchitis and infectious bursal disease. But these immunosuppressive effects were not observed in chickens infected with the virus at 2 weeks of age, or contact infected by growing in-contact with inoculated chickens from one day old. The clinical signs following infectious laryngotracheitis(ILT) vaccination in chickens infected with REV-HI at 1 day old were more severe than those of uninfected chickens, and some of REV-infected chickens(21.4%) were died after the vaccination. Mortality following virulent ILT virus infection was increased in REV-HI infected chickens. Effects of REV infection at one day old to susceptibilities to subsequent Chicken anemia agent (CAA) infection were also studied. Chickens were infected with REV-HI at 1 day old and subsequently inoculated CAA at 1, 7, 14 and 28 days old, respectively. Mortalities of the chickens infected with REV-HI and subsequent CAA infection were 100, 100, 40 and 0%, respectively, whereas 23, 8, 0 and 0% of chickens infected with only CAA were died, respectively. These above all results suggest that a Korean isolate of REV may be highly immunosuppressive.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.311-323
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• 2000

Immunosuppressive effects of reticuloendotheliosis virus (REV) infection in chickens were investigated. Primary antibody responses to Newcastle disease virus (strain B1) and sheep red blood cells were significantly low in chickens inoculated with the local isolate 89-74 of REV compared to those of uninfected chickens. In chickens infected with REV strain T or 89-74, blastogenesis of spleen cells and peripheral blood lymphocytes (PBL) to concanavalin A (Con A) was severely suppressed. When specific pathogen free (SPF) chickens were inoculated with the isolate, the suppressive effect was observed up to 7 weeks of age while, in the contact infected chickens, the suppression was absent. Similar suppressive effects were observed in chickens inoculated with REV strain T at 2, 3 and 4 weeks of age. When spleen cells or PBL from uninfected chickens were co-cultured with spleen cells or PBL from chickens infected with REV at 1 day-old or 2 week-old, the blastogenesis of the normal cells was suppressed. The suppressive effect of PBL from REV-infected chickens on normal lymphocytes was abrogated by the treatment with trypsin. However the suppressive activity of the REV-infected PBL was not influenced at removing machrophage from the cell suspension by incubation in plastic petri dishes. In addition to the immunosuppression, chickens infected with the REV isolate showed abnormal feather development (nakanuke), anemia, paralysis and retarded growth. Three out of 11 chickens inoculated with the isolate at day-old died between 6 and 9 weeks of age by bacterial infections.

• Animal Bioscience
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• v.35 no.6
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• pp.826-837
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• 2022

Objective: Cambodia is located within the distribution range of the red junglefowl, the common ancestor of domestic chickens. Although a variety of indigenous chickens have been reared in Cambodia since ancient times, their genetic characteristics have yet to be sufficiently defined. Here, we conducted a large-scale population genetic study to investigate the genetic diversity and population genetic structure of Cambodian indigenous chickens and their phylogenetic relationships with other chicken breeds and native chickens worldwide. Methods: A Bayesian phylogenetic tree was constructed based on 625 mitochondrial DNA D-loop sequences, and Bayesian clustering analysis was performed for 666 individuals with 23 microsatellite markers, using samples collected from 28 indigenous chicken populations in 24 provinces and three commercial chicken breeds. Results: A total of 92 haplotypes of mitochondrial D-loop sequences belonging to haplogroups A to F and J were detected in Cambodian chickens; in the indigenous chickens, haplogroup D (44.4%) was the most common, and haplogroups A (21.0%) and B (13.2%) were also dominant. However, haplogroup J, which is rare in domestic chickens but abundant in Thai red junglefowl, was found at a high frequency (14.5%), whereas the frequency of haplogroup E was considerably lower (4.6%). Population genetic structure analysis based on microsatellite markers revealed the presence of three major genetic clusters in Cambodian indigenous chickens. Their genetic diversity was relatively high, which was similar to findings reported for indigenous chickens from other Southeast Asian countries. Conclusion: Cambodian indigenous chickens are characterized by mitochondrial D-loop haplotypes that are common to indigenous chickens throughout Southeast Asia, and may retain many of the haplotypes that originated from wild ancestral populations. These chickens exhibit high population genetic diversity, and the geographical distribution of three major clusters may be attributed to inter-regional trade and poultry transportation routes within Cambodia or international movement between Cambodia and other countries.

• Korean Journal of Poultry Science
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• v.18 no.3
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• pp.141-150
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• 1991

A local isolate of chicken anemia agent (CAA), isolate 89-69. was tested for pathogenicity for chickens. When chickens from a specific pathogen free (SPF) flock were inoculated intramuscularly with the isolate at one day old, all the chickens showed severe anemia at 14 to 18 days post inoculation(DPI) and returned to normal at 25DPI, Some of the inoculated chickens (27∼33％) died between 13 to 17 DPI's with lesions of severe aplasia of bone marrow and thymic atrophy. In chickens kept in contact with inoculated chickens, some of the chickens had anemia at 25 and 28 DPI's. Virus could be reisolated from inoculated as well as in contact chickens till 21 DPI. Antibodies to CAA could be detected in all inoculated and in contact chickens when tested at 42 DPI by the indirect fluorescent antibody method. When chickens from a different SPF flock were inoculated at one day old, degrees of anemia, both in frequency of incidence and severity, were low These chickens were proved partly to have antibodies to CAA when tested for hatchmates. In a survey for antibodies to CAA in field chicken flocks, one out of 7 flocks(14％) aged 3 to 10weeks was antibody positive whereas 19 out of 20 flocks(95％) over 20 weeks of age were positive. Altogether 29 out of 39 flocks (74％) were antibody positive.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.10
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• pp.1566-1572
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• 2020

Objective: The extensive breeding of commercial chickens has led to a sharp decrease in the resources of many indigenous chickens, especially the indigenous chickens in the southeastern coastal region, which are on the verge of extinction, and the indigenous chickens in the northwestern region of China, which are also at risk. However, there are few reports on the evaluation of genetic diversity and conservation of genetic resources of indigenous chickens in remote areas in the Northwest of China. Methods: In the present study, the genetic diversity and phylogenetic relationship of six indigenous chickens from different regions were studied based on variation in mitochondrial DNA control region (D-loop), and the degree of introgression from commercial breeds into these chickens was determined by the amount of haplotype sharing between indigenous and commercial breeds. Results: Twenty-five polymorphic sites and 25 haplotypes were detected in 206 individuals. Principal component analysis showed that the Jingning chicken had the highest genetic diversity among the six indigenous chickens. According to the degree of introgression, the six indigenous breeds may be involved in haplotype sharing with commercial breeds, and the introgression from commercial chickens into the Haidong chicken is the most serious. Conclusion: The genetic uniqueness of indigenous chickens has been eroded, so it is necessary to consider the protection of their genetic resources. Phylogenetic analysis suggests that the six indigenous chickens have two major matrilineal origins: one from Yunnan or its surrounding areas in China and the other from the Indian subcontinent.

• Journal of Animal Science and Technology
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• v.65 no.2
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• pp.441-458
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• 2023

The poultry industry, which produces excellent sources of protein, suffers enormous economic damage from diseases. To solve this problem, research is being conducted on the early detection of infection according to the behavioral characteristics of poultry. The purpose of this study was to evaluate the potential of a non-movement behavior observation method to detect sick chickens. Forty 1-day-old Ross 308 males were used in the experiments, and an isolator equipped with an Internet Protocol (IP) camera was fabricated for observation. The chickens were inoculated with Salmonella enterica serovar Gallinarum A18-GCVP-014, the causative agent of fowl typhoid (FT), at 14 days of age, which is a vulnerable period for FT infection. The chickens were continuously observed with an IP camera for 2 weeks after inoculation, chickens that did not move for more than 30 minutes were detected and marked according to the algorithm. FT infection was confirmed based on clinical symptoms, analysis of cardiac, spleen and liver lesion scores, pathogen re-isolation, and serological analysis. As a result, clinical symptoms were first observed four days after inoculation, and dead chickens were observed on day six. Eleven days after inoculation, the number of clinical symptoms gradually decreased, indicating a state of recovery. For lesion scores, dead chickens scored 3.57 and live chickens scored 2.38. Pathogens were re-isolated in 37 out of 40 chickens, and hemagglutination test was positive in seven out of 26 chickens. The IP camera applied with the algorithm detected about 83% of the chickens that died in advance through non-movement behavior observation. Therefore, observation of non-movement behavior is one of the ways to detect infected chickens in advance, and it appears to have potential for the development of remote broiler management system.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.6
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• pp.679-684
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• 1996

This study evaluates the susceptibility of scaleless mutant chickens to very virulent Marek's disease virus (vvMDV) inoculation. One day old chickens were inoculated subcutaneously with Taiwanese isolates of LTB-1 and LTS-1 strains, and standard strain of Md/5. Compared with the non-inoculated group the vvMDV-inoculated chickens showed decreased body weights and atrophy of lymphoid organs before 35 days old. These results indicate that scaleless chickens show the same susceptibility as the wild type chickens to vvMDV infection. Furthermore, the protective effect of herpesvirus of turkey (HVT) vaccination at 1 day old against vvMDV challenge was evaluated. Scaleless mutant chickens of treated groups showed 20-30% early death, and 85.7-100% and 12.5-14.2% had lymphomatous lesions in visceral organs and peripheral nerves, respectively. No significant lesions were observed in non-challenged chickens of the control group. The HVT vaccination did not provide an effective protection against vvMDV infection. It is concluded that scaleless mutant chickens are susceptible to vvMDV infection.

• Korean Journal of Veterinary Research
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• v.48 no.4
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• pp.451-455
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• 2008

Body weights and blood biochemical values in chickens infected with reticuloendotheliosis virus (REV)-HI, a Korean isolate, were studied. REV-HI causes severe body weight depression in chickens inoculated but not in chicken contact-infected. Body weights of infected chickens in 3, 4, and 5 weeks after infection were 78%, 76% and 65% of those of control respectively. Blood glucose levels in REVinfected chickens were extremely high compared with those in control (226 $\geq$ 21 vs. 814 $\geq$91.3 mg/dl in week 2) during the experiment period. Triglyceride levels in REV-infected chickens were significantly higher in week 2 and 3, whereas in week 4, REV-infected chickens showed significantly lower levels than the control. Blood lipase, amylase and alkaline phosphatase levels of REV-infected chickens in week 2 were significantly higher, whereas cholesterol, magnesium and calcium values in week 4 were significantly lower than the control. Other blood biochemical values such as alkaline aminotransferase, aspartate aminotransferase, and $\gamma$-glutamyltransferase were nonsignificantly different from the control. These above results suggest that weight depression by REV may be related with increase of blood glucose, which indicated that REV-infected chickens could not use blood glucose as energy source.

• Korean Journal of Veterinary Research
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• v.48 no.4
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• pp.469-472
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• 2008

Necropsy was performed on a total of twenty three either white leghorn or ogol chickens which were more than 150 weeks of age. Among twenty three chickens examined, fifteen chickens were laying and the rest eight chickens were non-laying. On necropsy, neoplastic mass in the five chickens among non-laying chickens was found. These neoplastic masses were present mostly in the ovaries and one case in the liver and characterized by multifocal to coalescing 1 to 5 mm tan firm nodular formation. On histopathology, ovarian adenocarcinoma with widespread abdominal seeding and hepatic metastasis was diagnosed in the three chickens. Oviductal leiomyoma was also found in two chickens that had a focal well-demarcated nodules in the oviduct. Taken together, the number with ovarian adenocarcinoma among non-laying chickens over 150 week old was 37.5%. As most animal species do rarely develop ovarian tumors, the high rate of spontaneous ovarian adenocarcinoma in non-laying hen suggest that the hen is a proper model for human ovarian cancer study.