Selection of Male Donors in Local Chicken Breeds to Implement the Italian Semen Cryobank: Variability in Semen Quality, Freezability and Fertility.

Native breed conservation is an important component of poultry biodiversity. The aim of this work is to describe different steps that lead to donor selection for the implementation of the Italian Semen Cryobank of Autochthonous Chicken and Turkey Breeds. The variability within and between breeds was evaluated, and the stored semen reproductive capacity was in vivo tested using artificial insemination. Semen from Bionda Piemontese, Bianca di Saluzzo and Pepoi roosters was collected and processed. Concentration, volume, sperm membrane integrity, total motile sperm, progressive motile sperm and kinetic parameters were analyzed; sperm parameters accounting for bird variability were used to select male donors. Fresh semen quality parameters measured in donor ejaculates showed significant differences between breeds; no differences were found after cryopreservation. Variability in the fertilizing ability of cryopreserved semen was found within a breed (5-16%) and between birds within a breed (BP = 3-7%; BS = 7-31%; PP = 6-22%); only sperm quality parameters measured in fresh ejaculates, not frozen/thawed, may be associated with in vivo fertility results. In conclusion, sperm concentration and progressive motility were successfully used as selection parameters to identify chicken male donors with improved sperm quality for sperm cryobanking. However, new reliable sperm markers to predict cryopreserved semen's fertilizing ability are required.

Differential analysis of immunoglobulin gene expression pattern in chickens of distinct breeds and developmental periods.

Immunoglobulin is an essential component of the body's defense against pathogens, aiding in the recognition and clearance of foreign antigens. Research concerning immunoglobulin gene and its diversity of expression across different breeds within the same species is relatively scarce. In this study, we employed RACE (Rapid Amplification of cDNA Ends) technology, prepared DNA libraries, performed high-throughput sequencing, and conducted related bioinformatics analysis to analyze the differences in immunoglobulin gene diversity and expression at different periods in Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens. The study found that the composition of chicken immunoglobulin genes is relatively simple, with both the light chain and heavy chain having a functional V gene. Additionally, the mechanisms of immunoglobulin diversity generation tended to be consistent among different breeds and periods of chickens, primarily relying on abundant junctional diversity, somatic hypermutation (SHM), and gene conversion (GCV) to compensate for the limitations of low-level V(D)J recombination. As the age increased, the junctional diversity of IgH and IgL tended to diversify and showed similar expression patterns among different breeds. In the three chicken breeds, the predominant types of mutations observed in IGHV and IGLV SHM were A to G and G to A transitions. Specifically, IGLV exhibited a preference for A to G mutations, whereas IGHV displayed a bias toward G to A mutations. The regions at the junctions between framework regions (FR) and complementarity-determining regions (CDR) and within the CDR regions themselves are typically prone to mutations. The locations of GCV events in IGLV and IGHV do not show significant differences, and replacement segments are concentrated in the central regions of FR1, CDR, and FR2. Importantly, gene conversion events are not random occurrences. Additionally, our investigation revealed that CDRH3 in chickens of diverse breeds and periods the potential for diversification through the incorporation of cysteine. This study demonstrates that the diversity of immunoglobulin expression tends to converge among Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens, indicating that the immunoglobulin gene expression mechanisms in different breeds of chickens do not exhibit significant differences due to selective breeding.

Immunoglobulins play a key role in the organism's defense against pathogens, and their diverse expression allows the body to generate a wide array of antibodies. This diversity serves as a critical safeguard for the immune system against various pathogens. Natural geographical variances and artificial breeding and selection can potentially lead to different immune responses in distinct populations of the same species when confronted with the same pathogen. In this study, we investigated the diversity of immunoglobulin gene expression in the natural state of different chicken breeds (Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens) and at different periods from the perspective of immunoglobulin gene expression mechanism. We analyzed the diversity of immunoglobulin based on the results of high-throughput sequencing by extracting Fabricius bursa RNA, RACE (Rapid Amplification of cDNA Ends) technique, and constructing DNA libraries. Our study reveals that the junctional diversity, somatic hypermutation, CDR3 diversity, and gene conversion expression of immunoglobulins in Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens converge during the same time period. This indicates that the immunoglobulin gene expression mechanisms in different chicken breeds do not exhibit significant variations as a result of selective breeding.

Comparative peculiarities of genomic diversity in Gallus gallus domesticus chickens with decorative plumage: the muffs and beard phenotype.

Throughout history, humans have been attempting to develop the ornamental features of domestic animals in addition to their productive qualities. Many chicken breeds have developed tufts of elongated feathers that jut out from the sides and bottom of the beak, leading to the phenotype known as muffs and beard. It is an incomplete autosomal dominant phenotype determined by the Mb locus localised on chromosome GGA27. This project aimed to analyse the genetic diversity of chicken breeds using full genomic genotyping with the Chicken 60K BeadChip. A total of 53,313 Single Nucleotide Polymorphisms were analysed. DNA was obtained from breeds with the muffs and beard as a marker phenotype: Faverolles (n = 20), Ukrainian Muffed (n = 18), Orloff (n = 20), Novopavlov White (n = 20), and Novopavlov Coloured (n = 15). The Russian White (n = 20) was selected as an alternative breed without the muffs and beard phenotype. The chickens are owned by the Centre of Collective Use "Genetic Collection of Rare and Endangered Breeds of Chickens" (St. Petersburg region, Pushkin), and are also included in the Core Shared Research Facility (CSRF) and/or Large-Scale Research Facility (LSRF). Multidimensional scaling revealed that the Novopavlov White and the Novopavlov Coloured populations formed a separate group. The Ukrainian Muffed and the Orloff have also been combined into a separate group. Based on cluster analysis, with the cross-validation error and the most probable number of clusters K = 4 taken into account, the Orloff was singled out as a separate group. The Ukrainian Muffed exhibited a notable similarity with the Orloff under the same conditions. At K = 5, the populations of the Novopavlov White and the Novopavlov Coloured diverged. Only at K = 6, a distinct and separate cluster was formed by the Ukrainian Muffed. The Russian White had the greatest number of short (1-2 Mb) homozygous regions. If the HOXB8 gene is located between 3.402 and 3.404 Mb on chromosome GGA27, homozygous regions are rarely found in the chickens with the muffs and beard phenotype. Scanning the chicken genome with the Chicken 60K BeadChip provided enough information about the genetic diversity of the chicken breeds for the peculiarities of the development of the ornamental muffs and beard phenotypes in them to be understood. For example, Phoenix bantams, whose tail feathers grow throughout their lives, require greater consideration of husbandry conditions.

Polymorphisms and expressions of ADSL, MC4R and CAPN1 genes and their effects on economic traits in Egyptian chicken breeds.

In recent years, strategic plans for poultry production have emphasized quantitative traits, particularly body weight and carcass traits (meat yield), in response to overpopulation challenges. Candidate genes such as adenylosuccinate lyase (ADSL), melanocortin-4-receptor (MC4R), and calpain 1 (CAPN1) have played vital roles in this context due to their associations with muscle growth and body composition. This study aims to investigate the influence of polymorphisms and gene expressions of the aforementioned genes on body weight (BW), growth rate (GR), breast weight (BrW), and thigh weight (TW) across four distinct chicken breeds: Fayoumi, Matrouh, Mamourah, and Leghorn. The use of PCR-SSCP analysis revealed genetic polymorphisms through the identification of various patterns (genotypes) within the three examined genes. The ADSL, MC4R, and CAPN1 genes exhibited five, three, and two different genotypes, respectively. These polymorphisms displayed promising connections with enhancing economically significant production traits, particularly BW, BrW and TW. Furthermore, gene expression analyses were conducted on breast and thigh tissues obtained from the chicken breeds at 60 days of age, where ADSL and MC4R exhibited a noteworthy up-regulation in Fayoumi and Matrouh breeds, and down-regulation in Mamourah and Leghorn. In contrast, CAPN1 expression decreased across most breeds with a slight increase noted in Fayoumi breed. In conclusion, this investigation underscores the substantial impact of ADSL, MC4R, and CAPN1 genes on economically important production traits within Egyptian domestic chicken breeds. Consequently, these genes emerge as significant molecular markers, holding potential utility in avian selection and breeding programs aimed at enhancing productive performance.

External and internal quality traits of eggs from different ornamental chicken breeds.

This study analyzed the internal and external quality traits of eggs derived from hens of different breeds, including Silkie, Sultan, Cochin Bantam, Brahma and White Leghorn. The highest mean weight was noted for eggs originating from the White Leghorns breed, and the lowest was for eggs from the Cochin Bantams. Simultaneously, both a positive correlation between the egg weight and the percentage of albumen (r = 0.876) and a negative correlation between egg weight and the percentage of yolk (r = - 0.842) were found. The eggshell composition varied significantly in mean phosphorus amount, whereas the calcium content did not differ significantly. Despite this, eggshell strength varied significantly between breeds. Regarding cholesterol and fatty acid levels, the highest amount of cholesterol was noted in the Cochin Bantam breed, and the lowest was in the White Leghorn, although Leghorn was the breed characterized by the highest saturated fatty acid levels, and Cochin Bantam was the lowest. Regarding the polyunsaturated fatty acids (which have been proven to positively influence the cardiovascular system), the highest levels were obtained by Leghorn eggs, and the lowest were obtained by Silkie eggs. In conclusion, the study indicates that ornamental chicken breeds are a source of high-quality products, which could be attractive to consumers, additionally supporting traditional farming and animal genetic resources.

Productive Performances of Slow-Growing Chicken Breeds and Their Crosses with a Commercial Strain in Conventional and Free-Range Farming Systems.

Local chicken breeds play a vital role in promoting sustainability by preserving genetic diversity, enhancing resilience, and supporting local economies. These breeds are adapted to local climates and conditions, requiring fewer external resources and inputs for their maintenance. By conserving and utilizing local chicken breeds, sustainable farming practices can be incentivized, maintaining ecosystem balance and ensuring food security for future generations. The present study aimed at evaluating the growth performance and slaughter traits of two local Italian chicken breeds (Bionda Piemontese and Robusta Maculata) and their crosses with a medium-growth genotype (Sasso chicken®) reared in conventional and free-range farming systems. The conventional system used a high-energy high-protein diet in a closed barn with controlled temperature, humidity, and lighting, and a stocking density of 33 kg/m2. The free-range system used a low-input diet (low-energy low-protein diet composed of local and GMO-free feed ingredients), uncontrolled environmental conditions, and a stocking density of 21 kg/m2 in a barn with free access to an outdoor area. The birds were slaughtered at 84 days of age in both systems. The crossbred chickens showed the best results for growth performance in both farming systems compared to local breeds. Within genotype, the final live weight of chickens was similar in the two farming systems. In conclusion, slow-growth crossbreeds should be used in alternative farming systems, demonstrating better performance than pure local breeds.

Features of Fractal Conformity and Bioconsolidation in the Early Myogenesis Gene Expression and Their Relationship to the Genetic Diversity of Chicken Breeds.

Elements of fractal analysis are widely used in scientific research, including several biological disciplines. In this study, we hypothesized that chicken breed biodiversity manifests not only at the phenotypic level, but also at the genetic-system level in terms of different profiles of fractal conformity and bioconsolidation in the early myogenesis gene expression. To demonstrate this effect, we developed two mathematical models that describe the fractal nature of the expression of seven key genes in the embryonic breast and thigh muscles in eight breeds of meat, dual purpose, egg and game types. In the first model, we produced breed-specific coefficients of gene expression conformity in each muscle type using the slopes of regression dependencies, as well as an integral myogenesis gene expression index (MGEI). Additionally, breed fractal dimensions and integral myogenesis gene expression fractal dimension index (MGEFDI) were determined. The second gene expression model was based on plotting fractal portraits and calculating indices of fractal bioconsolidation. The bioconsolidation index of myogenesis gene expression correlated with the chick growth rate and nitric oxide (NO) oxidation rate. The proposed fractal models were instrumental in interpreting the genetic diversity of chickens at the level of gene expression for early myogenesis, NO metabolism and the postnatal growth of chicks.

Selective footprints and genes relevant to cold adaptation and other phenotypic traits are unscrambled in the genomes of divergently selected chicken breeds.

BACKGROUND: The genomes of worldwide poultry breeds divergently selected for performance and other phenotypic traits may also be affected by, and formed due to, past and current admixture events. Adaptation to diverse environments, including acclimation to harsh climatic conditions, has also left selection footprints in breed genomes. RESULTS: Using the Chicken 50K_CobbCons SNP chip, we genotyped four divergently selected breeds: two aboriginal, cold tolerant Ushanka and Orloff Mille Fleur, one egg-type Russian White subjected to artificial selection for cold tolerance, and one meat-type White Cornish. Signals of selective sweeps were determined in the studied breeds using three methods: (1) assessment of runs of homozygosity islands, (2) FST based population differential analysis, and (3) haplotype differentiation analysis. Genomic regions of true selection signatures were identified by two or more methods or in two or more breeds. In these regions, we detected 540 prioritized candidate genes supplemented them with those that occurred in one breed using one statistic and were suggested in other studies. Amongst them, SOX5, ME3, ZNF536, WWP1, RIPK2, OSGIN2, DECR1, TPO, PPARGC1A, BDNF, MSTN, and beta-keratin genes can be especially mentioned as candidates for cold adaptation. Epigenetic factors may be involved in regulating some of these important genes (e.g., TPO and BDNF). CONCLUSION: Based on a genome-wide scan, our findings can help dissect the genetic architecture underlying various phenotypic traits in chicken breeds. These include genes representing the sine qua non for adaptation to harsh environments. Cold tolerance in acclimated chicken breeds may be developed following one of few specific gene expression mechanisms or more than one overlapping response known in cold-exposed individuals, and this warrants further investigation.

Comparative Analysis of Molecular RFLP and SNP Markers in Assessing and Understanding the Genetic Diversity of Various Chicken Breeds.

Monitoring the genetic diversity of small populations is important with respect to conserving rare and valuable chicken breeds, as well as discovery and innovation in germplasm research and application. Restriction fragment length polymorphisms (RFLPs), the molecular markers that underlie multilocus DNA fingerprinting (MLDF), have historically been employed for this purpose, but over the past two decades, there has been an irreversible shift toward high-throughput single-nucleotide polymorphisms (SNPs). In this study, we conducted a comparative analysis of archived MLDF results and new data from whole-genome SNP genotyping (SNPg) among 18 divergently selected breeds representing a large sample of the world gene pool. As a result, we obtained data that fit the general concept of the phylogenetic distribution of the studied breeds and compared them with RFLP and SNP markers. RFLPs were found to be useful markers for retrospective assessment of changes in the genetic architecture and variability underlying the phenotypic variation in chicken populations, especially when samples from previous generations used for MLDF are unavailable for SNPg. These results can facilitate further research necessary to assess the possibility of extrapolating previous MLDF results to study the long-term dynamics of genetic diversity in various small chicken germplasm populations over time. In general, the whole-genome characterization of populations and breeds by multiple SNP loci will further form the basis for the development and implementation of genomic selection with the aim of effective use of the genetic potential of the domestic gene pool in the poultry industry.

Transcriptomic and Metabolomic Profile Analysis of Muscles Reveals Pathways and Biomarkers Involved in Flavor Differences between Caged and Cage-Free Chickens.

The cage-free system has gained a lot of interest in recent years because it can offer chickens more freedom and is easier to manage compared with free-range rearing systems, but few studies have focused on the effect of the cage-free rearing system on meat quality and flavor. In this study, 44 Jianghan chickens were reared in caged or cage-free systems to explore the effect of different rearing systems on meat-eating quality. Sensory evaluation of cooked muscles showed that the leg muscle aroma, juiciness, and flavor intensity significantly improved by the cage-free rearing. The cage-free hens had significantly lower body weight, abdominal fat percentage, and meat fat content, but higher meat moisture content. The cage-free group had brighter breast muscle and redder leg muscle color 24 h after slaughter. Transcriptomic and metabolomic profile analysis of the leg muscle samples showed that the cage-free rearing changed biosynthesis pathways associated with glycogen metabolism, lipid and fatty acid biosynthesis and transport, muscle cellular type, and cellular components, which were related to raw meat quality. Different rearing systems also resulted in differences in glycolipid metabolism, lipid metabolism, and altered levels of intramuscular fat content and other flavor precursors. Pathways such as glycerolipid metabolism, adipocytokine signaling, and metabonomic pathways such as linoleic acid, glycerophospholipid, arginine, proline, and ß-alanine metabolism may be responsible for the meat quality and flavor change.

Lipid profile of sperm cells in Thai native and commercial roosters and its impact on cryopreserved semen quality.

Plasma membrane lipids are the key factor in the ability of chicken sperm to be frozen. They ensure fluidity and flexibility of the sperm membrane for effective viability and motility during in vitro storage. The objective of this study was to compare the lipid profiles of different native and commercial chicken breeds: native Thai (Pradu Hang Dam) roosters and commercial (Rhode Island Red) roosters, with respect to their frozen sperm quality. In addition, lipid peroxidation and antioxidant enzymes superoxidase dismutase (SOD) and catalase (CAT) were also examined. Semen was collected from 12 roosters of each breed. For fresh semen, parameters assessed include semen volume, pH, sperm concentration, sperm motility, and viability, while for frozen semen, the parameters assessed were sperm motility and viability. Moreover, other parameters assessed included malondialdehyde (MDA) concentration, activities of SOD and CAT, and fatty acid profile. We found that sperm viability and motility of frozen semen were higher in the commercial breed than in the native breed (P < 0.05). The commercial chicken breed had higher MDA concentration than the native breed (P < 0.05), but antioxidant enzymes remained unchanged in both. Levels of arachidonic acid (AA; C20:4n-6) and docosahexaenoic acid (DHA; C22:6n-3) were significantly higher (P < 0.05) in the commercial than in the native breed; however, n-6 to n-3 ratios were not different. In conclusion, our study found that lipid profiles have an influence on frozen sperm viability and motility between the breeds. Polyunsaturated fatty acids, particularly AA and DHA, are beneficial to sperm quality.

Genetic Variability in Local and Imported Germplasm Chicken Populations as Revealed by Analyzing Runs of Homozygosity.

Preserving breed uniqueness and purity is vitally important in developing conservation/breeding programs for a germplasm collection of rare and endangered chicken breeds. The present study was aimed at analyzing SNP genetic variability of 21 small local and imported purebred and F1 crossbred populations and identifying crossbreeding events via whole-genome evaluation of runs of homozygosity (ROH). The admixture models more efficiently reflected population structure, pinpointing crossbreeding events in the presence of ancestral populations but not in their absence. Multidimensional scaling and FST-based analyses did not discriminate properly between purebred populations and F1 crossbreds, especially when comparing related breeds. When applying the ROH-based approach, more and longer ROHs were revealed in purebred individuals/populations, suggesting this as an effective implement in genome-wide analysis of germplasm breed purity.

Estimating genetic diversity and population structure of 22 chicken breeds in Asia using microsatellite markers.

OBJECTIVE: Estimating the genetic diversity and structures, both within and among chicken breeds, is critical for the identification and conservation of valuable genetic resources. In chickens, microsatellite (MS) marker polymorphisms have previously been widely used to evaluate these distinctions. Our objective was to analyze the genetic diversity and relationships among 22 chicken breeds in Asia based on allelic frequencies. METHODS: We used 469 genomic DNA samples from 22 chicken breeds from eight Asian countries (South Korea, KNG, KNB, KNR, KNW, KNY, KNO; Laos, LYO, LCH, LBB, LOU; Indonesia, INK, INS, ING; Vietnam, VTN, VNH; Mongolia, MGN; Kyrgyzstan, KGPS; Nepal, NPS; Sri Lanka, SBC) and three imported breeds (RIR, Rhode Island Red; WLG, White Leghorn; CON, Cornish). Their genetic diversity and phylogenetic relationships were analyzed using 20 MS markers. RESULTS: In total, 193 alleles were observed across all 20 MS markers, and the number of alleles ranged from 3 (MCW0103) to 20 (LEI0192) with a mean of 9.7 overall. The NPS breed had the highest expected heterozygosity (Hexp, 0.718±0.027) and polymorphism information content (PIC, 0.663±0.030). Additionally, the observed heterozygosity (Hobs) was highest in LCH (0.690±0.039), whereas WLG showed the lowest Hexp (0.372±0.055), Hobs (0.384±0.019), and PIC (0.325±0.049). Nei's DA genetic distance was the closest between VTN and VNH (0.086), and farthest between KNG and MGN (0.503). Principal coordinate analysis showed similar results to the phylogenetic analysis, and three axes explained 56.2% of the variance (axis 1, 19.17%; 2, 18.92%; 3, 18.11%). STRUCTURE analysis revealed that the 22 chicken breeds should be divided into 20 clusters, based on the highest ΔK value (46.92). CONCLUSION: This study provides a basis for future genetic variation studies and the development of conservation strategies for 22 chicken breeds in Asia.

Association of antioxidant defense system with semen attributes vis a vis fertility in exotic and indigenous chicken breeds.

The present study was designed to ascertain the association of antioxidant defense system with semen attributes and fertility in RIR (Rhode Island Red), PR (Punjab Red), RIR x local cross, Aseel and Kadaknath breeds. Based on sperm attributes, roosters of each breed were divided into two group i.e. G-I (exhibiting >50% sperm attributes) and G-II (exhibiting <50% sperm attributes). Motility, viability, membrane-, acrosome-, DNA-integrity and fertility differed significantly (p < 0.05) among the breeds, representing maximum in PR roosters and least in Aseel roosters. Values of sperm attributes and fertility rate were also significantly (p < 0.05) higher in G-I compared to G-II roosters in exotic as well as indigenous breeds. MDA content differed significantly (p < 0.05) in spermatozoa of five breeds. It indicated a least oxidant stress in PR and highest in Aseel. MDA concentration was significantly (P < 0.05) higher in G-II (28.36 ± 2.40-96.0 ± 6.4) than G-I (13.65 ± 1.81-52.22 ± 6.4) roosters in all breeds. Antioxidant enzyme activity varied significantly (p < 0.05) among the breeds and groups within the breeds. Significantly (p < 0.05) higher activity of four enzymes was evident in G-II as compared to G-I roosters irrespective of the breed. A moderate to strong negative correlation was perceived among LPO, SOD, GPX, catalase, GRE and sperm attributes/fertility rate. A moderate to strong positive correlation (0.21-0.92) among LPO and antioxidant enzymes revealed that with the increase in LPO, antioxidant enzymes increase too and vice versa in all breeds. Likewise, positive correlation between sperm attributes and fertility revealed that higher sperm attributes contribute to the high fertility of roosters. This is one of the first reports on complete set of antioxidant enzymes and oxidative stress in relation to sperm attributes and fertility in different five chicken breeds. A complete antioxidant enzyme system seems to modulate the oxidative stress, sperm attributes and fertility. It may be possible to use LPO as a fertility marker to select the roosters for breeding purpose in the chicken breeds.

Genetic resistance of eight native Egyptian chicken breeds having chicken B-cell marker 6 gene post-challenge with field strain of Marek's disease-induced tumor virus.

AIM: The aim of this work was to detect chicken B-cell marker 6 (ChB6) gene in some native breeds in Egypt and find the relationship between founded genes in these different breeds to determine the resistance of native Egyptian breeds of chicken to Marek's disease (MD). MATERIALS AND METHODS: A total of 14 different chicken breeds (30 each) including ten native breeds in addition to SPF Lohmann, High Line, Bovans, and Roodiland were used. Blood samples were collected for the detection of (ChB6) by polymerase chain reaction (PCR) assay and sequenced to determine the presence or absence of ChB6 gene. Experimental infection was done using local field isolated MD virus (MDV) of 11 (1 day old) unvaccinated chick breeds having no maternal antibodies against MDV. Ten breeds of them carry ChB6 gene, eight breeds were native, and the rest two breeds were SPF Lohmann and High Line in addition to a group of ChB6 gene-lacking breed (Bovans) were infected. Spleen samples were collected from all infected breeds at 20th, 25th, 30th, 35th, and 40th weeks post-infection and tested by PCR assay for the detection of MDV. Furthermore, at 40th week post-infection, tumorized spleen sample of Bovans breed was collected and prepared for examination by transmission electron microscope (TEM) to confirm the presence of MDV. RESULTS: Our results revealed the positivity of 10 out of 14 breeds (Gimmizah, Sinai, Dandarawi, Fayoumi, Golden Montazah, Matrouh, Beheri, Dokki, SPF Lohmann, and High Line) to the presence of ChB6 gene and resistance to MDV infection, while the Bovans, Mandarah, Inshas and Roodiland breeds lack the ChB6 gene and are susceptible to MDV infection. The collected spleen samples revealed negative for the presence of challenged MDV by PCR in 10 breeds (Gimmizah, Sinai, Dandarawi, Fayoumi, Golden Montazah, Matrouh, Beheri, Dokki, SPF Lohmann, and High Line) and positive for Bovans breed. TEM is used to confirm MDV infection in Bovans group which demonstrated tumors. CONCLUSION: The study confirms the relationship between the presence of ChB6 gene in our native breeds and the absence of tumors.

Genetic diversity and population structure analysis of eight local chicken breeds of Southern Xinjiang.

1. The genetic diversity and population structure were studied for eight local chicken breeds, including Anjiyan (AN), Hetian Black (HH), Hetian Ma (HM), Aheqi (AH), Baicheng You (BC), Hejing (HJ), Tashkurghan (TS) and Ruoqiang (RQ), in the Southern Xinjiang region of China, using 20 microsatellite markers. 2. Total 336 alleles were obtained from all chicken breeds, with a mean of 16.8 alleles per locus. The polymorphism information content ranged from 0.444 to 0.911, with a mean of 0.729 and almost all of the loci showed significant deviation from Hardy-Weinberg standards. The observed and expected heterozygosity of the eight breeds ranged from 0.5 to 0.677 and from 0.656 to 0.774, with the lowest observed in the AN and the highest in BC breed. The average breed genetic diversity was 0.655 for AN and 0.766 for BC chickens. 3. According to the neighbour-joining (NJ) method, three main clusters were identified in the NJ phylogenetic tree with AN and RQ breeds in one clade, HH and HM breeds in the second clade and TS, HJ, AH and BC breeds in the third clade. 4. Based on STRUCTURE analysis, the most likely cluster number of all breeds was K = 4, whereby HH and HM breeds formed one cluster and AH, BC, HJ and TS formed another, and RQ, AN chicken formed their own distinct cluster. These results indicated that HH and HM breeds had similar genetic background, as did the breeds of AH, BC, HJ and TS. RQ, AN breed had unique genetic backgrounds, distinct from the other breeds. Genetic introgression was detected from AN to HH and HM. 5. The results of the current study can be used as baseline genetic information to implement effective conservation programs and to make better use of these local chicken breeds, especially for the AN, RQ and TS breeds.

Expression of APOB, ADFP and FATP1 and their correlation with fat deposition in Yunnan's top six famous chicken breeds.

1. Adipose differentiation related protein (ADFP), fatty acid transport protein 1 (FATP1) and apolipoprotein B (APOB) are suspected to play an important role in determining intramuscular fat and in overall meat quality. 2. Yunnan's top six famous chicken breeds (the Daweishan Mini, Yanjin Black-bone, Chahua, Wuding, Wuliangshan Black-bone and Piao chicken) are known for the high quality of their meat, but little is known about their expression of these three genes. 3. The present study aimed to examine the ADFP, FATP1 and APOB genes in different tissues of these six breeds at different development stages. The subcutaneous fat from the back midline and front, abdominal fat, liver and muscle tissue was sampled at 28, 49, 70, 91 and 112 days. The expression of ADFP, FATP1 and APOB was measured by real-time PCR. 4. The results showed that the expression of the three genes differed depending on age, tissue types and breeds. However, the expression of the three genes correlated with fat traits. In conclusion, the expression of the ADFP, FATP1 and APOB genes is associated with the fat traits of Yunnan's top six chicken breeds. These results could help with molecular marker screening and marker-assisted breeding to improve the quality of poultry for meat production.

Genetic diversity of mtDNA D-loop sequences in four native Chinese chicken breeds.

1. To explore the genetic diversity of Chinese indigenous chicken breeds, a 585 bp fragment of the mitochondrial DNA (mtDNA) region was sequenced in 102 birds from the Xichuan black-bone chicken, Yunyang black-bone chicken and Lushi chicken. In addition, 30 mtDNA D-loop sequences of Silkie fowls were downloaded from NCBI. The mtDNA D-loop sequence polymorphism and maternal origin of 4 chicken breeds were analysed in this study. 2. The results showed that a total of 33 mutation sites and 28 haplotypes were detected in the 4 chicken breeds. The haplotype diversity and nucleotide diversity of these 4 native breeds were 0.916 ± 0.014 and 0.012 ± 0.002, respectively. Three clusters were formed in 4 Chinese native chickens and 12 reference breeds. Both the Xichuan black-bone chicken and Yunyang black-bone chicken were grouped into one cluster. Four haplogroups (A, B, C and E) emerged in the median-joining network in these breeds. 3. It was concluded that these 4 Chinese chicken breeds had high genetic diversity. The phylogenetic tree and median network profiles showed that Chinese native chickens and its neighbouring countries had at least two maternal origins, one from Yunnan, China and another from Southeast Asia or its surrounding area.

Epidemiological investigation of Mycoplasma Synoviae in native chicken breeds in China.

BACKGROUD: Mycoplasma synoviae (M. synoviae) is widely distributed around the world, and leads to serious economic losses in the world every year. Nevertheless, the incidence and epidemiology of M. synoviae infection in China have remained unclear. RESULTS: In this study we demonstrate that over 9773 broiler chicken flocks in 16 Chinese provinces were affected by M. synoviae between 2010 and 2015. Our epidemiological study revealed that M. synoviae was widely prevalent in multi-aged Chinese native breeder chickens, and the prevalence of M. synoviae in embryos of breeders reached up to 16.29%. In addition, our data showed that chickens aged 14 days or younger carried simultaneously high levels of maternal antibody against M. synoviae and high M. synoviae infection (10%), and low M. synoviae antibody levels in breeders and high proportion of M. synoviae infection in embryos could increase the chances of incidence in the offspring. Finally, our results also indicated that 3- to 7-week-old chickens might be most the susceptible to M. synoviae and, therefore, might play a key role in the horizontal transmission of M. synoviae. CONCLUSION: Our findings suggest that M. synoviae is widely circulating in Chinese native chickens, accordingly, effective control measures are urgently needed to control the spread.

Novel avian leukosis viruses from domestic chicken breeds in mainland China.

Two novel avian leukosis viruses (ALVs) were isolated from 1380 whole blood samples taken from domestic chicken breeds in China. The two ALVs were uniquely different from the env (Envelope) genes of ALV A-J and carried an LTR (long terminal repeat) cluster from ALV-E. Large scale sequence analysis further showed that these ALVs (with different env and LTRs) were recently endemic in domestic chicken breeds in both China and Japan. The emergence of these novel ALVs is challenging the current ALV eradication program, and as such novel ALVs should be monitored in a timely and careful manner to stop their transmission and further recombination in the future.