• Korean Journal of Poultry Science
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• v.42 no.2
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• pp.157-167
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• 2015

We compared the degrees of stress response of 12 domestic purebred chicken strains that have been bred at National Institute of Animal Science, RDA, Korea since 1980. As a physiological marker of stress response, the expression levels of heat shock protein (HSP)-70, HSP-$90{\alpha}$, HSP-$90{\beta}$, hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) genes and telomere length were measured by quantitative real-time polymerase chain reaction using the lymphocytes of 1,101 chickens. There was significant difference in HSP-70, HSP-$90{\alpha}$, HMGCR expression and telomere length among the strains. There was also significant difference in HSP-$90{\alpha}$, HSP-$90{\beta}$, and HMGCR expression between male and female chickens. Different age groups of chicken exhibited different expression levels of HSP-70, HSP-$90{\alpha}$ and telomere length. The results of the HSPs expression level suggested that, the strains of R, L and Y were highly resistant to stress, whereas the strains of S, O and W were susceptible to stress. Although the statistical differences in some of HSPs gene expression existed between genders, the HSP expression results varied in different strains that some opposed to the others, and there might be interaction between strains and genders, which conclude that there was no difference in stress response between male and female chickens. Moreover, despite of significant difference in some of HSPs expression level, it was considered that there was no difference in stress response between ages due to the inconsistent trends among HSP markers.

• Korean Journal of Poultry Science
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• v.46 no.2
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• pp.77-86
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• 2019

This study was conducted to compare the heat stress response and production performance of chicks hatched in winter and summer. Among the 2,090 Korean native chickens examined, 1,156 hatched in winter and 934 hatched in summer. The amount of telomeric DNA, the expression of heat shock protein (HSP) genes, survival rate, egg production, and body weight were analyzed to evaluate the stress response and production performance of chickens. The results showed that the expression of HSP-70, $HSP-90{\alpha}$, and $HSP-90{\beta}$ genes in the winter-hatched chickens were significantly higher than those in the summer-hatched chickens during the growing and laying period (P<0.05). There was no significant difference in the amount of telomeric DNA between summer- and winter-hatched chickens. The survival rate was significantly higher in the summer-hatched chickens than in the winter-hatched chickens at the laying period (P<0.01). The hen-day egg production and egg weight in the summer-hatched chickens were also significantly higher than those in the winter-hatched chickens (P<0.05). In contrast, age of sexual maturity of winter-hatched chickens was significantly earlier than that of summer-hatched chickens (P<0.01). The body weights from birth to 24 weeks were significantly lighter in the summer-hatched chickens than in the winter-hatched chickens, however, it was reversed after 28 weeks (P<0.05). In conclusion, the chicks hatched in the summer are more resistant to heat stress, with better productivity than the chicks hatched in the winter. These results suggest that the chicks grown at high temperatures have greater adaptability to the thermal environment.

• Korean Journal of Veterinary Service
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• v.43 no.3
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• pp.139-145
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• 2020

This study was carried out to identify the occurrence of transovarian transmitted diseases and antibody positive rates among Korean native breeder chickens. The infection rates with Salmonella pullorum and Salmonella gallinarum among 16-week-old, 36-week-old, and 56-week-old breeder chickens and the antibody positive rates to Egg Drop Syndrome '76, Mycoplasma gallisepticum and Mycoplasma synoviae among 16-week-old, 18-week-old, and 56-week-old breeder chickens were identified, and the antibody positive rates to seven major transovarian transmitted diseases among 1-day-old chicks were investigated. As a result, no infection with Salmonella pullorum and Salmonella gallinarum was found among the investigated subjects of all ages. Vaccinated breeder chickens showed the 100% antibody positive rate to Egg Drop Syndrome '76, and unvaccinated breeder chickens showed the 100% antibody negative rate to Mycoplasma gallisepticum and Mycoplasma synoviae, confirming that there was no infection with Mycoplasma gallisepticum and Mycoplasma synoviae. As a result of the antibody tests of the 1-day-old chicks for transovarian transmitted diseases, it was found that vaccinated chicks showed good antibody positive rates to avian encephalomyelitis, chicken infectious anemia, and avian reovirus, confirming that they had power of defense against the relevant infectious diseases, and that unvaccinated chicks showed the 100% antibody negative rates to avian leukosis, chicken reticuloendotheliosis, and Mycoplasma synoviae, confirming that there was no infection with the relevant diseases. Given that the results of this study showed that among the transovarian transmitted diseases of chickens, there was no history of infection with diseases against which vaccination was not administered and high antibody positive rates were found with diseases against which vaccination was administered, it is judged that chickens with good power of defense against diseases were bred, and it is deemed that constant monitoring and vaccination against transovarian transmitted diseases will be necessary for the control and prevention of the diseases.

• Korean Journal of Poultry Science
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• v.43 no.3
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• pp.177-189
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• 2016

This study was conducted to verify the relationships between the expression values of stress-related markers and their production performances in 25 strains of Korean domestic chicken breeds. For stress response markers, the amount of telomeric DNA; expression levels of heat shock protein (HSP)-70, $HSP-90{\alpha}$, and $HSP-90{\beta}$; and comet scores were analyzed. Production performances were measured by the survival rate, body weights, days at first egg laying, egg weight and hen housed egg production. The results showed that the production traits and values of stress-related markers showed significant differences between strains. In general, the stress response of pure bred chickens with heavy weights was relatively high, while that of hybrid chickens with light weights was relatively low. The correlation coefficients between telomere contents and body weights showed that there were weak negative relationships. However, the correlations of telomere content with the survival rate and egg production were weakly positive after 20 weeks old. The expression levels of HSP genes and DNA damage rate (comet scores) were positively correlated to body weight, but were negatively correlated to the survival rate and egg production. The results implied that increasing body weight was associated with increasing HSPs expression and the DNA damage rate was associated with decreasing telomere content. In addition, increasing HSPs expression and the DNA damage rate decreased the survival rate and egg production, but the relationships with the telomere content was the reverse. Correlations among the stress-related markers showed that there were significant correlation coefficients between all of the marker values. HSPs expression was negatively correlated to the telomere content, while it was positively correlated to the DNA damage rate. There was a highly negative correlation between the telomere content and DNA damage rate. In conclusion, increasing the HSP values and DNA damage rate can promote telomere reduction, which led to a decrease in disease resistance and robustness of the chicken. Thus, increasing the stress response was verified to adversely affect the laying performance and viability of chickens.