Reproduction performance of 21 inbred experimental lines of White Leghorns was evaluated based on samples of reproduction records over a period of eight consecutive years. Two lines (63 and 72) have been extensively u...Reproduction performance of 21 inbred experimental lines of White Leghorns was evaluated based on samples of reproduction records over a period of eight consecutive years. Two lines (63 and 72) have been extensively used in studies, especially in research seeking for genetic and epigenetic factors underlying resistance to avian tumor virus-induced diseases in chickens. The other 19 lines are recombinant congenic strains (RCS), which were generated by crossing lines 63 and 72 followed by two consecutive backcrosses to the line 63 and then full-sib mating. In theory, each RCS processes 7/8 of progenitor background line 63 genome and a random sample (1/8) of the progenitor donor line 72 genome. All 21 inbred lines share a common major histocompatibility complex haplotype, B*2. The estimated average fertility of the 21 inbred lines ranged from 72.9% (RCS-J) up to 96.8% (RCS-P). Both progenitor lines 63 and 72 were observed with lower average fertility (82.4% and 81.6%, respectively) in comparison with the RCS except the RCS-J, suggesting a substantial polygenic component underlying the fertility phenotype. The average embryo mortality rate ranged from 14.5% (RCS-P) up to 47.0% (RCS-M). The background line 63 fell at about the middle of the range (28.3%) significantly higher than the donor line 72 (15.7%), which was among the group with the lowest embryo mortality. By definition, hatchability of fertile eggs is reversely correlated with embryo mortality. The average hatchability ranged from 26.5% (RCS-M) up to 66.8% (line 72) while the background line 63 remained (46.6%) at about the middle of the range. The variability of the average embryo mortality and hatchability observed among the 21 inbred lines indicated the two correlated traits also follow polygenic models of inheritance. Findings from this study paves the way for further investigation on genetic and environmental influence over reproductive performance of inbred lines of chickens, and particularly in understanding and improving the reproduction fitness of invaluable genetic resources like these inbred lines.展开更多
Broken and cracked eggshells cause major economic losses to the egg production industry. An F2 population of 262 hens obtained by crossing a strong egg shell line with a weak egg shell line of the White Leghorn breed ...Broken and cracked eggshells cause major economic losses to the egg production industry. An F2 population of 262 hens obtained by crossing a strong egg shell line with a weak egg shell line of the White Leghorn breed was used for detecting the quantitative trait loci （QTL） affecting eggshell quality. The 2 lines were developed from the same founder population by two-way selection for egg shell strength with nondestructive deformation. Of the 1 014 microsatellite markers tested, 35 were mapped on 10 autosomal linkage groups. There was no informative marker on chromosome Z. The QTLs associated with 7 traits, i.e., body weight, short length of egg, long length of egg, eggshell strength, eggshell thickness （EST）, eggshell weight （ESW）, and egg weight （EW）, were identified. Highly significant （P〈0.01） QTLs associated with EST and ESW and a significant （P〈 0.05） QTL associated with EW were mapped to a region flanking ABR0545 and ABR0362 on chromosome 9. These QTLs are good candidates to be employed in the development of strategies for reducing the number of broken and cracked eggs in commercial layer houses by employing marker assisted selection.展开更多
Jinyang Ⅲ strain of late-feathering Leghorn chicken has been successively selectedwith comprehensive index for 7 generations by family breeding method of mass-first and closing-late.As compared with the control,the s...Jinyang Ⅲ strain of late-feathering Leghorn chicken has been successively selectedwith comprehensive index for 7 generations by family breeding method of mass-first and closing-late.As compared with the control,the selection result is average 7 days earlier at first laying forevery generation,more than 13 of egg number at age of 300 days and higher than 0.63% for sur-vival rate in laying period.Main laying performances are as follows:age at first laying 156±10.4days;egg number at age of 300 days 99±26.O;egg number and egg weight at 72 weeks of age 226±38.8 and 58.2±4.6g respectively.Through cross breeding selection,a series of white-shell au-tosexing chicken has been developed.More than 5.1 million commercial sex-identified chickenhave been released as well.展开更多
Melanoblasts originating from neural crest cells can migrate through the mesenchyme of the developed embryo and give rise to melanocytes.Unlike the melanocytes that are confined to the integument in other vertebrates,...Melanoblasts originating from neural crest cells can migrate through the mesenchyme of the developed embryo and give rise to melanocytes.Unlike the melanocytes that are confined to the integument in other vertebrates,melanocytes in Silky Fowl can reach the ventral regions of the embryos owing to differences in gene expression in the process of melanoblasts migration.In this study,we used microarray profiling to identify differences in gene expression between White Leghorn and Silky Fowl.Differential expression of 2517 microarray probes(P<0.01,Fold Change>2)was observed in Silky Fowl compared to White Leghorn.After filtration by cluster analysis,functional annotation and pathway analysis,eight differentially expressed genes were identified to be closely related to the development of melanocytes.Moreover,differences in expression of immune genes were also detected between Silky Fowl and White Leghorn.The differentially expressed genes associated with melanocyte development were verified by q-PCR,and results were highly consistent with the microarray data.The genes with significantly altered expression involved in melanoblast migration and development suggested that different microenvironments resulted in the abnormal melanoblast migration in Silky Fowl,although there were no big differences in melanoblast development between these two breeds.The candidate genes discovered in this study are beneficial to understand the molecular mechanism of hyperpigmentation in Silky Fowl.展开更多
文摘Reproduction performance of 21 inbred experimental lines of White Leghorns was evaluated based on samples of reproduction records over a period of eight consecutive years. Two lines (63 and 72) have been extensively used in studies, especially in research seeking for genetic and epigenetic factors underlying resistance to avian tumor virus-induced diseases in chickens. The other 19 lines are recombinant congenic strains (RCS), which were generated by crossing lines 63 and 72 followed by two consecutive backcrosses to the line 63 and then full-sib mating. In theory, each RCS processes 7/8 of progenitor background line 63 genome and a random sample (1/8) of the progenitor donor line 72 genome. All 21 inbred lines share a common major histocompatibility complex haplotype, B*2. The estimated average fertility of the 21 inbred lines ranged from 72.9% (RCS-J) up to 96.8% (RCS-P). Both progenitor lines 63 and 72 were observed with lower average fertility (82.4% and 81.6%, respectively) in comparison with the RCS except the RCS-J, suggesting a substantial polygenic component underlying the fertility phenotype. The average embryo mortality rate ranged from 14.5% (RCS-P) up to 47.0% (RCS-M). The background line 63 fell at about the middle of the range (28.3%) significantly higher than the donor line 72 (15.7%), which was among the group with the lowest embryo mortality. By definition, hatchability of fertile eggs is reversely correlated with embryo mortality. The average hatchability ranged from 26.5% (RCS-M) up to 66.8% (line 72) while the background line 63 remained (46.6%) at about the middle of the range. The variability of the average embryo mortality and hatchability observed among the 21 inbred lines indicated the two correlated traits also follow polygenic models of inheritance. Findings from this study paves the way for further investigation on genetic and environmental influence over reproductive performance of inbred lines of chickens, and particularly in understanding and improving the reproduction fitness of invaluable genetic resources like these inbred lines.
文摘Broken and cracked eggshells cause major economic losses to the egg production industry. An F2 population of 262 hens obtained by crossing a strong egg shell line with a weak egg shell line of the White Leghorn breed was used for detecting the quantitative trait loci （QTL） affecting eggshell quality. The 2 lines were developed from the same founder population by two-way selection for egg shell strength with nondestructive deformation. Of the 1 014 microsatellite markers tested, 35 were mapped on 10 autosomal linkage groups. There was no informative marker on chromosome Z. The QTLs associated with 7 traits, i.e., body weight, short length of egg, long length of egg, eggshell strength, eggshell thickness （EST）, eggshell weight （ESW）, and egg weight （EW）, were identified. Highly significant （P〈0.01） QTLs associated with EST and ESW and a significant （P〈 0.05） QTL associated with EW were mapped to a region flanking ABR0545 and ABR0362 on chromosome 9. These QTLs are good candidates to be employed in the development of strategies for reducing the number of broken and cracked eggs in commercial layer houses by employing marker assisted selection.
文摘Jinyang Ⅲ strain of late-feathering Leghorn chicken has been successively selectedwith comprehensive index for 7 generations by family breeding method of mass-first and closing-late.As compared with the control,the selection result is average 7 days earlier at first laying forevery generation,more than 13 of egg number at age of 300 days and higher than 0.63% for sur-vival rate in laying period.Main laying performances are as follows:age at first laying 156±10.4days;egg number at age of 300 days 99±26.O;egg number and egg weight at 72 weeks of age 226±38.8 and 58.2±4.6g respectively.Through cross breeding selection,a series of white-shell au-tosexing chicken has been developed.More than 5.1 million commercial sex-identified chickenhave been released as well.
基金supported by Natural Science Foundation of China(31472082,30771535)the National High-tech R&D Program of China(2013AA102501).
文摘Melanoblasts originating from neural crest cells can migrate through the mesenchyme of the developed embryo and give rise to melanocytes.Unlike the melanocytes that are confined to the integument in other vertebrates,melanocytes in Silky Fowl can reach the ventral regions of the embryos owing to differences in gene expression in the process of melanoblasts migration.In this study,we used microarray profiling to identify differences in gene expression between White Leghorn and Silky Fowl.Differential expression of 2517 microarray probes(P<0.01,Fold Change>2)was observed in Silky Fowl compared to White Leghorn.After filtration by cluster analysis,functional annotation and pathway analysis,eight differentially expressed genes were identified to be closely related to the development of melanocytes.Moreover,differences in expression of immune genes were also detected between Silky Fowl and White Leghorn.The differentially expressed genes associated with melanocyte development were verified by q-PCR,and results were highly consistent with the microarray data.The genes with significantly altered expression involved in melanoblast migration and development suggested that different microenvironments resulted in the abnormal melanoblast migration in Silky Fowl,although there were no big differences in melanoblast development between these two breeds.The candidate genes discovered in this study are beneficial to understand the molecular mechanism of hyperpigmentation in Silky Fowl.
