• Journal of Veterinary Science
• /
• v.19 no.6
• /
• pp.850-854
• /
• 2018

Novel H5N6 highly pathogenic avian influenza viruses (HPAIVs) were isolated from duck farms and migratory bird habitats in South Korea in November to December 2017. Genetic analysis demonstrated that at least two genotypes of H5N6 were generated through reassortment between clade 2.3.4.4 H5N8 HPAIVs and Eurasian low pathogenic avian influenza virus in migratory birds in late 2017, suggesting frequent reassortment of clade 2.3.4.4 H5 HPAIVs and highlighting the need for systematic surveillance in Eurasian breeding grounds.

• Asian-Australasian Journal of Animal Sciences
• /
• v.25 no.7
• /
• pp.1009-1014
• /
• 2012

Environmental stress boosts the levels of stress hormones and accelerates energy expenditure which subsequently imbalance the body's homeostasis. L-ascorbic acid (L-AA) has been recognized to mitigate the negative impact of environmental stress on production performances in birds. The present investigation was carried out to elucidate the effect of different dietary levels of L-AA on production performance, egg quality traits and fertility in Japanese quail at low ambient temperature. Sixty matured females (15 wks) were equally divided into three groups (20/group) based on the different dietary levels of L-AA (0, 250 and 500 ppm) and coupled with an equal number of males (1:1) obtained from the same hatch. They were managed in uniform husbandry conditions without restriction of feed and water at 14 h photo-schedule. Except for feed efficiency, body weight change, feed consumption and hen-day egg production were recorded highest in 500 ppm L-AA supplemented groups. Among the all egg quality traits studied, only specific gravity, shell weight and thickness differed significantly (p<0.05) in the present study. Fertility was improved significantly ($p{\leq}0.01$) to a dose dependent manner of L-AA. The findings of the present study concluded that dietary L-AA can be a caring management practice at least in part to alleviate the adverse effect of cold induced stress on production performance in Japanese quail.

• Korean Journal of Poultry Science
• /
• v.41 no.3
• /
• pp.173-179
• /
• 2014

While use of mass rearing systems improved poultry production, chances of exposing to contagious diseases have been increased, making flocks more vulnerable to diseases. Diseases of interest which affects egg production adversely include Low pathogenic avian influenza (LPAI), Infectious bronchitis (IB), Avian meta-pneumoviral infection (aMPV) and Egg drop syndrome'76 (EDS'76). This report collected and analyzed 5,385 serum samples, which were collected from 1,330 different chicken flock, provided by Chungbuk National University, Avian Disease Laboratory at 2009. Serums were analyzed based on rearing stages; 0~1.3weeks (wks) (maternal antibody period), >1.3~3 wks (starting period), >3~10 wks (growing period), >10~22 wks (developing period), >22~40 wks (peak laying period), >40~60 wks (late laying period) and over 60 wks (post-molting period). Results showed the 99.7% of the tested flocks were immunized against ND and73.8%, 97.1%, 78,2% and 78% of the flocks were immunized against other 4 agents (LPAI, IB, EDS'76, aMPV). Maternal antibody was transferred to enough quantity for NDV. Generally, antibody titers which were developed at 22 weeks were stabilized permanently for life. In case of IB and aMPV, infection titer emerged as early as 10 weeks and the titer was increased from 99.4% to 100% for life. EDS76 showed increase in titers, reflecting decreased frequency of vaccination programs. Overall, this study displayed general trends of major viral disease in layers, but considering the trend of development of preventive measures and evolution of pathogens, conducting serological surveys on a regular basis is important.

• Journal of Veterinary Science
• /
• v.22 no.2
• /
• pp.21.1-21.6
• /
• 2021

In this study, we describe the isolation and characterization of previously unreported Y280-lineage H9N2 viruses from two live bird markets in Korea in June 2020. Genetic analysis revealed that they were distinct from previous H9N2 viruses circulating in Korea and had highest homology to A/chicken/Shandong/1844/2019(H9N2) viruses. Their genetic constellation showed they belonged to genotype S, which is the predominant genotype in China since 2010, where genotype S viruses have infected humans and acted as internal gene donors to H5 and H7 zoonotic influenza viruses. Active surveillance and control measures need to be enhanced to protect the poultry industry and public health.

• Asian-Australasian Journal of Animal Sciences
• /
• v.9 no.4
• /
• pp.455-459
• /
• 1996

The genetic parameters for various economic traits were estimated in a White Leghorn population selected for part period egg production over 16 generations. In early part of selection, egg number had moderate to high heritability (0.26 to 0.51) while age at sexual maturity, egg weight and body weight at 20 and 40 weeks of age had high heritability (0.54 to 0.83). The sire component heritability for all the traits except 20 week body weight declined in later periods of selection. Sex linked gene effects for egg number and age at sexual maturity were more important in early periods of selection in comparison to the later periods, while maternal effects remained important for 20 week body weight in all the periods. Egg number was negatively correlated with egg weight ($r_{G(S)}=-0.36$), age at sexual maturity ($r_{G(S)}=-0.84$) and 40 week body weight ($r_{G(S)}=-0.84$), while it was positively correlated with 20 week body weight ($r_{G(S)}=-0.34$) in base generation. The genetic association between egg number and 40 week body weight changed not only in magnitude but also in direction in later periods. The genetic correlation of egg number with egg weight as well as with age at sexual maturity also decreased in magnitude in later periods of selection.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.8
• /
• pp.1060-1068
• /
• 2011

The LDH isozymes are key catalysts in the glycolytic pathway of energy metabolism. It is well known that the distribution of the LDH isozymes vary in accordance with the metabolic requirements of different tissues. The substrates required for energy production change noticeably at successive stages of testes development suggesting a significant flexibility in the expression of glycolytic enzymes. Therefore, expression of LHDA and LDHB mRNAs was examined in adult and prepubertal quail testis. The mRNA of both LDHA and LDHB were expressed and no significant difference was observed in prepubertal testes. The mRNA levels of LDHB significantly increased during testicular development. In the adult testis, LDHA mRNA was not expressed. Expression studies revealed the presence of different LDH isozymes during testicular development. In contrast, electrophoresis of both testicular samples revealed only single band at a position indicative of an extreme type of LDH isozyme in quail testes. Furthermore, nucleotide and amino acid sequence analysis revealed significant similarity to chicken, duck and rock pigeon. These sequence results confirmed the similarity of LDHA and LDHB subunit protein in different avian species.

• Korean Journal of Poultry Science
• /
• v.50 no.4
• /
• pp.231-240
• /
• 2023

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive disease in young chickens, and causes considerable economic losses to the poultry industry. More than 30 years ago, an antigenic variant IBDV (avIBDV) was reported in chicken farms in the United States. Recently, a novel avIBDV exhibited clear differences in molecular characteristics compared with previous variant strains. This study investigated the molecular characteristics of recently isolated avIBDV strains in Korea. Strains of avIBDV were confirmed by reverse transcription PCR (RT-PCR) and were propagated in 10-day-old specific-pathogen-free (SPF) embryonated chicken eggs through chorioallantoic membrane (CAM) inoculation. Multiple sequence alignment and phylogenetic analyses of hypervariable regions VP2 gene revealed that the strains originated from two different avIBDV lineages (G2a and G2d). In our results, we confirmed the co-existence and prevalence of avIBDV genogroup G2a and G2d in chicken farms. It is necessary to study the protective efficacy of current vaccines against avIBDVs.

• Korean Journal of Veterinary Service
• /
• v.26 no.1
• /
• pp.51-56
• /
• 2003

Avian pneumoviros(APV), also known as avian rhinotracheitis virus(ARTV), affects both turkeys and chickens and is known to be the primary causative agent of turkey rhinotracheitis (TRT). The aim of this study was to establish the presence or absence of antibodies to avian pneumovirus in the commercial poultry population of Korea. For this purpose, chicken serum samples were obtained and tested by an enzyme-linked immunosorbent assay (ELISA). The tested serum was collected in laying hens with reduction of egg production or normal in Gyeongbuk province. A total of 184 sera representing 42 different poultry farms of the Gyeongbuk region of Korea were included in this study. Laying hens of 16 different farms with reduction of egg production and laying hens of 26 different farms with clinically healthy at the time of serum sampling were considered positive to antibody against APV. In the farms with reduction of egg production, positive farm to antibody against avian pneumovirus were 11 of 16 different farms(68.8%) and positive sera were 47(58.8%) of 80 different serum. In the farms with clinically healthy flock, positive farm to antibody against avian pneumovirus were 12(46.2%) of 26 different farms and positive serum sample were 39(37.5%) of 104 different sera. According to the results tested to 42 different farms in 14 city, 8 of 14 city have flocks with antibody positive laying hens against APV, 1 of 14 city have antibody suspicious and 5 of 14 city shown antibody negative, respectively.

• Korean Journal of Poultry Science
• /
• v.31 no.2
• /
• pp.129-136
• /
• 2004

Avian influenza viruses infect humans, horses, swine, other mammals, and a wide variety of domesticated and wild birds. Modem poultry industries worldwide are at risk of infection with avian influenza. Low pathogenic avian influenza can easily change to highly pathogenic form especially when introduced into areas of high density commercial poultry. Outbreaks of highly pathogenic avian influenza are becoming progressively more expensive to control according to the growth of the poultry industry worldwide. Future strategies for avian influenza control and prevention should involve a combination of early detection and characterization of virus using advanced molecular biologic techniques, quarantine, selective depopulation and vaccination of flocks.

• Journal of Life Science
• /
• v.28 no.8
• /
• pp.962-968
• /
• 2018

Type A influenza virus is circulating in wild birds and can infect wide ranges of hosts such as humans, pigs, domestic birds, and other mammals. Many subtypes of avian influenza viruses are circulating in aquatic birds. Most avian influenza viruses found in aquatic birds are low pathogenic avian influenza viruses. Highly pathogenic avian influenza viruses have been found in waterfowls since 2005. It is known that H5 and H7 subtypes of avian influenza viruses can be mutated into highly pathogenic avian influenza viruses in domestic poultry. In this study, we isolated novel reassortant H7N7 avian influenza virus from the fecal materials of migratory birds in the Western part of South Korea in 2016, and analyzed the sequences of all its eight genes. The genetic analysis of our isolate, A/waterfowl/Korea/S017/2016 (H7N7) indicates that it was reassortant avian influenza virus containing genes of both avian influenza viruses of wild birds and domestic ducks. Phylogenetic analysis showed that our isolate belongs to Eurasian lineage of avian influenza virus. Since avian influenza viruses continue to evolve, and H7-subtype avian influenza virus can mutate into the highly pathogenic avian influenza viruses, which cause the great threat to humans and animals, we closely survey the infections in both wild birds, and domestic poultry, and mammals.