Background:The frequency of recombination events varies across the genome and between individuals,which may be related to some genomic features.The objective of this study was to assess the frequency of recombination ...Background:The frequency of recombination events varies across the genome and between individuals,which may be related to some genomic features.The objective of this study was to assess the frequency of recombination events and to identify QTL(quantitative trait loci)for recombination rate in two purebred layer chicken lines.Methods:A total of 1200 white-egg layers(WL)were genotyped with 580 K SNPs and 5108 brown-egg layers(BL)were genotyped with 42 K SNPs(single nucleotide polymorphisms).Recombination events were identified within half-sib families and both the number of recombination events and the recombination rate was calculated within each0.5 Mb window of the genome.The 10%of windows with the highest recombination rate on each chromosome were considered to be recombination hotspots.A BayesB model was used separately for each line to identify genomic regions associated with the genome-wide number of recombination event per meiosis.Regions that explained more than 0.8%of genetic variance of recombination rate were considered to harbor QTL.Results:Heritability of recombination rate was estimated at 0.17 in WL and 0.16 in BL.On average,11.3 and 23.2 recombination events were detected per individual across the genome in 1301 and 9292 meioses in the WL and BL,respectively.The estimated recombination rates differed significantly between the lines,which could be due to differences in inbreeding levels,and haplotype structures.Dams had about 5%to 20%higher recombination rates per meiosis than sires in both lines.Recombination rate per 0.5 Mb window had a strong negative correlation with chromosome size and a strong positive correlation with GC content and with CpG island density across the genome in both lines.Different QTL for recombination rate were identified in the two lines.There were 190 and 199 non-overlapping recombination hotspots detected in WL and BL respectively,28 of which were common to both lines.Conclusions:Differences in the recombination rates,hotspot locations,and QTL regions associated with genomewide recombination were observed between lines,indicating the breed-specific feature of detected recombination events and the control of recombination events is a complex polygenic trait.展开更多
The chickens studied were from a pure line of brown shell egg-type (YAFA) female grandparents of 17-week-old. Plasima very low density lipoprotein (VLDL) concentration was measured with turbidimetric assay. The experi...The chickens studied were from a pure line of brown shell egg-type (YAFA) female grandparents of 17-week-old. Plasima very low density lipoprotein (VLDL) concentration was measured with turbidimetric assay. The experiment results showed that the phenotypic correlations between 29-week or 50-week plasma VLDL concentration and egg production (EP) were positive in the early stage of laying period, but those in the latter stage were negative. Selection for low plasma VLDL concentration will decrease the EP in the early stage of laying period but increase the one in the latter stage. There was a significant negative phenotypic correlation between the age at first egg (AFE) and 18-week body weight (BW). The phenotypic correlation between 29-week plasma VLDL concentration and the AFE was negative. AFE was influenced by BW and body fatness as well. There was significant positive phenotypic correlation between plasima VLDL concentration and body weights (BWs) at the same stage in laying period and the phenotypic correlation was also positive between 29-week plasma VLDL concentration and the BW at middle stage of laying period, indicating that selection for low plasma VLDL concentration would reduce BWs at various stages to different degree.展开更多
Leucocytozoonosis was found in three layer farms in chickens with suspected fatty liver or fatty liver hemorrhagic syndrome in Korea between 2009 and 2011.These layer chicken flocks showed both mortality and decreased...Leucocytozoonosis was found in three layer farms in chickens with suspected fatty liver or fatty liver hemorrhagic syndrome in Korea between 2009 and 2011.These layer chicken flocks showed both mortality and decreased egg production for one or two weeks when they were between 59 and 82 weeks old.At the necropsy,the most prominent gross lesions were found in the liver,which was enlarged,had a fragile texture,exhibited yellowish discolorations,and had various hemorrhagic lesions.Tissue reactions associated with megaloschizonts specific for Leucocytozoon caulleryi were prominent upon microscopic examination of the liver without significant lipidosis.In addition,the ovaries and uterus were the most affected organs for Leucocytozoon caulleryi multiplication,which led to decreased egg productions.Molecular studies with formalin-fixed,paraffin-embedded tissues were performed in search of a partial region of the cytochrome b gene for hemosporidian parasites.Based on these results,the causal agent was determined to be closely related to Leucocytozoon caulleryi reported in Japan and Malaysia.In this study,we describe recently re-occurring leucocytozoonosis in layer chickens,which required histopathology for disease diagnosis.To prevent outbreaks and maintain chicken health and egg production,layer chickens need to be monitored for symptoms of leucocytozoonosis.展开更多
The aim of this research was to know the effect of herbal as immunomodulator on chicken layer vaccinated with avian influenza. A total of 60 chickens were alloted into three treatment groups： control group （KA）, gr...The aim of this research was to know the effect of herbal as immunomodulator on chicken layer vaccinated with avian influenza. A total of 60 chickens were alloted into three treatment groups： control group （KA）, group KB and group KC, with 20 chicken each group. All the chickens were vaccinated with Newcastle disease （ND） in the age of one week, and a week later they were vaccinated with avian influenza （AI）. The chickens in group KB were drunken with herbal solution containing of 5 g turmeric （Curcuma heyneana Val.） and 25 g phyllanthus （Phyllanthus niruri L.） and group KC were drunken with herbal solution containing of 36 g the herbals formula Viranur and 25 g phyllanthus （Phyllanthus niruri L.）, respectively for four weeks. Thirty days after AI vaccinated, all of chicken were weighed and necropsied. Samples from bursa of Fabricius, tymus and spleen were taken for weighing and histopathological examination. The weight indexs of bursa of Fabricius, tymus and spleen were not significantly different between control group and treatment group in the considered statistically significance （P 〉 0.05）, but the treatment groups （KB and KC） had higher weight index. The histopathologically changes of spleen in both control group and treatment groups were not different, although in the group KC, in bursa of Fabricius, there was lymphocyte increase in its lymphoid follicles; and in the group KB and KC, the tymus were more widening in the cortex than medulla. The conclusion of this study showed that the herbals can stimulate lymphocyte activity.展开更多
Background:Gut microbiota plays a key role in health,immunity,digestion,and production in layers.Factors such as environment,diet,diseases,stress,and flock management significantly affect gut microbiota;however,it is ...Background:Gut microbiota plays a key role in health,immunity,digestion,and production in layers.Factors such as environment,diet,diseases,stress,and flock management significantly affect gut microbiota;however,it is not known how potential stressors such as intramuscular injections or feed withdrawal alter the composition of gut microbiota that result in increased the shedding level of foodborne pathogens.In the current study,the effects of intramuscular corticosterone injection and feed withdrawal were evaluated to understand their role in Salmonella Typhimurium shedding and changes in the composition of gut microbiota in layers.Results:Salmonella shedding was observed for 8 weeks post-infection.There was a significant increase in Salmonella Typhimurium count after intramuscular injection and feed withdrawal.The Salmonella infected and the negative control groups showed significant differences in the abundance of different genera in gut microbiota at week 1 and up to week 7 post infection.The infected group showed a significant reduction in alpha diversity of gut microbiota.Firmicutes reduced significantly(P<0.05)after intramuscular injection,while the feed withdrawal groups did not cause any significant changes in Proteobacteria-Firmicutes ratio.Furthermore,intramuscular injection resulted in a significant change in alpha diversity of gut microbiota.Conclusions:Exposure of chicks to relatively low dose of Salmonella Typhimurium can lead to persistent shedding in pullets.The Salmonella Typhimurium infection disrupted the gut microbiota composition immediately after infection.The potential stress of intramuscular injection and feed withdrawal significantly increased the Salmonella Typhimurium count in faeces.The intramuscular injection also resulted in a significant alteration of the Proteobacteria-Firmicutes ratio,which could increase the risk of dysbiosis.展开更多
基金supported by Hy-Line Int.,the EW group,and Agriculture and Food Research Initiative competitive grants 2009–35205-05100 and 2010–65205-20341 from the USDA National Institute of Food and Agriculture Animal Genome Program
文摘Background:The frequency of recombination events varies across the genome and between individuals,which may be related to some genomic features.The objective of this study was to assess the frequency of recombination events and to identify QTL(quantitative trait loci)for recombination rate in two purebred layer chicken lines.Methods:A total of 1200 white-egg layers(WL)were genotyped with 580 K SNPs and 5108 brown-egg layers(BL)were genotyped with 42 K SNPs(single nucleotide polymorphisms).Recombination events were identified within half-sib families and both the number of recombination events and the recombination rate was calculated within each0.5 Mb window of the genome.The 10%of windows with the highest recombination rate on each chromosome were considered to be recombination hotspots.A BayesB model was used separately for each line to identify genomic regions associated with the genome-wide number of recombination event per meiosis.Regions that explained more than 0.8%of genetic variance of recombination rate were considered to harbor QTL.Results:Heritability of recombination rate was estimated at 0.17 in WL and 0.16 in BL.On average,11.3 and 23.2 recombination events were detected per individual across the genome in 1301 and 9292 meioses in the WL and BL,respectively.The estimated recombination rates differed significantly between the lines,which could be due to differences in inbreeding levels,and haplotype structures.Dams had about 5%to 20%higher recombination rates per meiosis than sires in both lines.Recombination rate per 0.5 Mb window had a strong negative correlation with chromosome size and a strong positive correlation with GC content and with CpG island density across the genome in both lines.Different QTL for recombination rate were identified in the two lines.There were 190 and 199 non-overlapping recombination hotspots detected in WL and BL respectively,28 of which were common to both lines.Conclusions:Differences in the recombination rates,hotspot locations,and QTL regions associated with genomewide recombination were observed between lines,indicating the breed-specific feature of detected recombination events and the control of recombination events is a complex polygenic trait.
文摘The chickens studied were from a pure line of brown shell egg-type (YAFA) female grandparents of 17-week-old. Plasima very low density lipoprotein (VLDL) concentration was measured with turbidimetric assay. The experiment results showed that the phenotypic correlations between 29-week or 50-week plasma VLDL concentration and egg production (EP) were positive in the early stage of laying period, but those in the latter stage were negative. Selection for low plasma VLDL concentration will decrease the EP in the early stage of laying period but increase the one in the latter stage. There was a significant negative phenotypic correlation between the age at first egg (AFE) and 18-week body weight (BW). The phenotypic correlation between 29-week plasma VLDL concentration and the AFE was negative. AFE was influenced by BW and body fatness as well. There was significant positive phenotypic correlation between plasima VLDL concentration and body weights (BWs) at the same stage in laying period and the phenotypic correlation was also positive between 29-week plasma VLDL concentration and the BW at middle stage of laying period, indicating that selection for low plasma VLDL concentration would reduce BWs at various stages to different degree.
基金provided by the project of National Institute of Environment Research(No.2015080777)
文摘Leucocytozoonosis was found in three layer farms in chickens with suspected fatty liver or fatty liver hemorrhagic syndrome in Korea between 2009 and 2011.These layer chicken flocks showed both mortality and decreased egg production for one or two weeks when they were between 59 and 82 weeks old.At the necropsy,the most prominent gross lesions were found in the liver,which was enlarged,had a fragile texture,exhibited yellowish discolorations,and had various hemorrhagic lesions.Tissue reactions associated with megaloschizonts specific for Leucocytozoon caulleryi were prominent upon microscopic examination of the liver without significant lipidosis.In addition,the ovaries and uterus were the most affected organs for Leucocytozoon caulleryi multiplication,which led to decreased egg productions.Molecular studies with formalin-fixed,paraffin-embedded tissues were performed in search of a partial region of the cytochrome b gene for hemosporidian parasites.Based on these results,the causal agent was determined to be closely related to Leucocytozoon caulleryi reported in Japan and Malaysia.In this study,we describe recently re-occurring leucocytozoonosis in layer chickens,which required histopathology for disease diagnosis.To prevent outbreaks and maintain chicken health and egg production,layer chickens need to be monitored for symptoms of leucocytozoonosis.
文摘The aim of this research was to know the effect of herbal as immunomodulator on chicken layer vaccinated with avian influenza. A total of 60 chickens were alloted into three treatment groups： control group （KA）, group KB and group KC, with 20 chicken each group. All the chickens were vaccinated with Newcastle disease （ND） in the age of one week, and a week later they were vaccinated with avian influenza （AI）. The chickens in group KB were drunken with herbal solution containing of 5 g turmeric （Curcuma heyneana Val.） and 25 g phyllanthus （Phyllanthus niruri L.） and group KC were drunken with herbal solution containing of 36 g the herbals formula Viranur and 25 g phyllanthus （Phyllanthus niruri L.）, respectively for four weeks. Thirty days after AI vaccinated, all of chicken were weighed and necropsied. Samples from bursa of Fabricius, tymus and spleen were taken for weighing and histopathological examination. The weight indexs of bursa of Fabricius, tymus and spleen were not significantly different between control group and treatment group in the considered statistically significance （P 〉 0.05）, but the treatment groups （KB and KC） had higher weight index. The histopathologically changes of spleen in both control group and treatment groups were not different, although in the group KC, in bursa of Fabricius, there was lymphocyte increase in its lymphoid follicles; and in the group KB and KC, the tymus were more widening in the cortex than medulla. The conclusion of this study showed that the herbals can stimulate lymphocyte activity.
基金post graduate research scholarships from the Australian Eggs and the University of Adelaide。
文摘Background:Gut microbiota plays a key role in health,immunity,digestion,and production in layers.Factors such as environment,diet,diseases,stress,and flock management significantly affect gut microbiota;however,it is not known how potential stressors such as intramuscular injections or feed withdrawal alter the composition of gut microbiota that result in increased the shedding level of foodborne pathogens.In the current study,the effects of intramuscular corticosterone injection and feed withdrawal were evaluated to understand their role in Salmonella Typhimurium shedding and changes in the composition of gut microbiota in layers.Results:Salmonella shedding was observed for 8 weeks post-infection.There was a significant increase in Salmonella Typhimurium count after intramuscular injection and feed withdrawal.The Salmonella infected and the negative control groups showed significant differences in the abundance of different genera in gut microbiota at week 1 and up to week 7 post infection.The infected group showed a significant reduction in alpha diversity of gut microbiota.Firmicutes reduced significantly(P<0.05)after intramuscular injection,while the feed withdrawal groups did not cause any significant changes in Proteobacteria-Firmicutes ratio.Furthermore,intramuscular injection resulted in a significant change in alpha diversity of gut microbiota.Conclusions:Exposure of chicks to relatively low dose of Salmonella Typhimurium can lead to persistent shedding in pullets.The Salmonella Typhimurium infection disrupted the gut microbiota composition immediately after infection.The potential stress of intramuscular injection and feed withdrawal significantly increased the Salmonella Typhimurium count in faeces.The intramuscular injection also resulted in a significant alteration of the Proteobacteria-Firmicutes ratio,which could increase the risk of dysbiosis.
