Effects of heat stress on antioxidant defense system, inflammatory injury, and heat shock proteins of Muscovy and Pekin ducks: evidence for differential thermal sensitivities.

Rising temperatures are severely affecting the mortality, laying performance, and meat quality of duck. Our aim was to investigate the effect of acute heat stress on the expression of heat shock proteins (HSPs: HSP90, 70, 60, 40, and 10) and inflammatory factors (nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)) and antioxidant enzyme activity (superoxide dismutase (SOD), malondialdehybe (MDA), catalase (CAT), total antioxidant capacity (T-AOC)) in livers of ducks and to compare the thermal tolerance of Pekin and Muscovy ducks exposed to acute heat stress. Ducks were exposed to heat at 39 ± 0.5 °C for 1 h and then returned to 20 °C for 1 h followed by a 3-h recovery period. The liver and other tissues were collected from each individual for analysis. The mRNA levels of HSPs (70, 60, and 40) increased in both species, except for HSP10, which was upregulated in Muscovy ducks and had no difference in Pekin ducks after heat stress. Simultaneously, the mRNA level of HSP90 decreased in the stress group in both species. Morphological analysis indicated that heat stress induced tissue injury in both species, and the liver of Pekin ducks was severely damaged. The activities of several antioxidant enzymes increased in Muscovy duck liver, but decreased in Pekin duck. The mRNA levels of inflammatory factors were increased after heat stress in both duck species. These results suggested that heat stress could influence HSPs, inflammatory factors expression, and the activities of antioxidant enzymes. Moreover, the differential response to heat stress indicated that the Muscovy duck has a better thermal tolerance than does the Pekin duck.

Effect of dietary fatty acids on serum parameters, fatty acid compositions, and liver histology in Shaoxing laying ducks.

The effects of different fatty acid (FA) contents in diet on serum parameters, FA compositions of eggs and meat, and liver morphological changes were studied in Shaoxing laying ducks. A total of 264 ducks at 17 weeks were fed a control diet or a diet containing 30 g/kg fish oil (FO), 25 g/kg sunflower oil (SO), or 30 g/kg palm oil with 20 g/kg beef tallow (PBO). Malondialdehyde (MDA) content in the liver and the serum of ducks fed the PBO diet was significantly (P<0.05) higher than that of ducks fed the other diets. Triglyceride (TG) and total cholesterol (TC) levels were significantly lower (P<0.05) in ducks fed the FO diet. Serum TC also was lower in ducks fed the SO diet. Superoxide dismutase (SOD) activity was also affected by diets. The contents of polyunsaturated FAs (PUFAs) in eggs and meat were significantly higher (P<0.001) in ducks fed the FO and SO diets than in ducks fed the control diet. The level of C22:6 (n-3) FA in ducks fed the FO diet was significantly higher than that in ducks fed the other diets. However, the conversion efficiency of the longer-chain C20:5 (n-3) FA was higher than that of C22:6 (n-3). Ducks fed the PBO diet exhibited lipid droplet accumulation in the liver. These results demonstrate that a diet enriched with different FAs has strong effects on serum lipid levels and the deposition of PUFAs into tissue lipids.

Assignment of CCR7 gene to chicken chromosome 27 by radiation hybrid panel mapping.

The protein encoded by CC chemokine receptor 7 (CCR7) is a member of the G protein-coupled receptor family. This receptor was identified as a gene induced by the Epstein-Barr virus (EBV), and is thought to be a mediator of EBV effects on B lymphocytes. This receptor is expressed in various lymphoid tissues and activates B and T lymphocytes. It has been shown to control the migration of memory T cells to inflamed tissues, as well as stimulate dendritic cell maturation. To map the CCR7 gene in chicken chromosome, a 6 000 rads chicken-hamster radiation hybrid panel (ChickRH6) was used. PCR of samples from ChickRH6 revealed that the location of CCR7 gene is linked to the maker SEQ0347 (6 cR away) with LOD score of 16.6 and that the marker SEQ0347 is located on chromosome 27 at 27 cR of RH (radiation hydrid) map. We compared the corresponding human mRNA sequence with the predicted coding sequence of chicken CCR7 gene, and found that the assembled contig shared a high percentage of similarity with that of the human gene.

[Advance in association studies of major histocompatibility complex (MHC) gene polymorphisms with traits of resistance against infectious disease in chickens].

Chicken is a main poultry in China. Molecular breeding for disease resistance plays an important role in the control of diseases, especially infectious diseases. Choice of genes for disease resistance is the key technology of molecular breeding. The MHC is of great interest to poultry breeding scientists for its extraordinary polymorphism and close relation with traits of resistance against infectious diseases. The article gives a detailed introduction about the association of MHC gene polymorphisms with traits of resistance against infectious diseases in chickens and looks towards the future of application of MHC in molecular breeding of chicken for disease resistance.

[Analysis of genetic relationship among Chinese native chicken breeds using microsatellites marker].

The allele frequencies, heterozygosity (H), mean heterozygosity, polymorphism information content (PIC) and genetic relationships were studied in Luyuan chicken, Gushi chicken, Tibetan chicken, Baier chicken, Xianju chicken, Chahua chicken, Dagu chicken,Beijing Fatty chicken, Langshan chicken, Henan Game chicken,Taihe Silkies chicken and Xiaoshan chicken using seven microsatellite DNA markers. The results showed that there were differences among allele fequencies of seven microsatellite loci in 12 Chinese native chicken breeds. Among the 12 Chinese native chicken breeds, mean heterozygosity of Luyuan chicken was the highest (0.5929), and that of Chahua chicken was the lowest (0.3514). There were similar results in PIC. By fuzzy cluster analysis was found that the genetic relationship between Taihe Silkies chicken and Henan Game chicken was the nearest, and that between Gushi chicken and the other chicken breeds was the most distant. The 12 Chinese native chicken breeds were divided into three group by fuzzy cluster analysis. The first group included Taihe Silkies chicken, Henan Game chicken, Langshan chicken, Xiaoshan chicken, Dagu chicken, Beijing Fatty chicken and Luyuan chicken, the second group included Chahua chicken, Tibetan chicken, Xianju chicken and Baier chicken, and the third group included Gushi chicken.