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Chicken primordial germ cells (PGCs) are important cells with significant implications in preserving genetic resources, chicken breeding and production, and basic research on genetics and development. Currently, chicken PGCs can be cultured long-term in vitro to produce single-cell clones. However, systematic exploration of the cellular characteristics of these single-cell clonal lines has yet to be conducted. In this study, single-cell clonal lines were established from male and female PGCs of Rugao Yellow Chicken and Shouguang Black Chicken, respectively, using a micropipette-based method for single-cell isolation and culture. Analysis of glycogen granule staining, mRNA expression of pluripotency marker genes (POUV , SOX2 , NANOG), germ cell marker genes (DAZL , CVH), and SSEA-1, EMA-1, SOX2, C -KIT, and CVH protein expression showed positive results, indicating that PGCs maintain normal cellular properties after single-cell cloning. Furthermore, tests on proliferation ability and gene expression levels in PGC single-cell clonal lines showed high expression of the pluripotency-related genes and TERT compared to control PGCs, and PGC single-cell clonal lines demonstrated higher proliferation ability. Finally, green fluorescent protein (GFP)-PGC single-cell clonal lines were established, and it was found that these single-cell clonal lines could still migrate into the gonads of recipients, suggesting their potential for germ-line transmission. This study systematically validated the normal cellular characteristics of PGC single-cell clonal lines, indicating that they could be applied in genetic modification research on chickens. • PGC single-cell clonal lines were created from two breeds of chickens. • PGCs maintain their normal cellular properties after single-cell cloning. • Single-cell clonal lines of PGCs could still migrate into the gonads of recipients. [ABSTRACT FROM AUTHOR]

The introduction of exotic breeds and the cultivation of new lines by breeding companies have posed challenges to native chickens in South China, including loss of breed characteristics, decreased genetic diversity, and declining purity. Understanding the population genetic structure and genetic diversity of native chickens in South China is crucial for further advancements in breeding efforts. In this study, we analyzed the population genetic structure and genetic diversity of 321 individuals from 10 different breeds in South China. By comparing commercial chickens with native ones, we identified selection signatures occurring between local chickens and commercial breeds. The analysis of population genetic structure revealed that the native chicken populations in South China exhibited a considerable level of genetic diversity. Moreover, the commercial lines of Xiaobai chicken and Huangma chicken displayed even higher levels of genetic diversity, which distinguished them from other native varieties at the clustering level. However, certain individuals within these commercial varieties showed a discernible genetic relationship with the native populations. Notably, both commercial varieties also retained a significant degree of genetic similarity to their respective native counterparts. In order to investigate the genomic changes occurring during the commercialization of native chickens, we employed 4 methods (Fst, ROD, XPCLR, and XPEHH) to identify potential candidate regions displaying selective signatures in Southern Chinese native chicken population. A total of 168 (identified by Fst and ROD) and 86 (identified by XPCLR and XPEHH) overlapping genes were discovered. Functional annotation analysis revealed that these genes may be associated with reproduction and growth (SAMSN1, HYLS1, ROBO3, FGF14, PRSS23), musculoskeletal development (DNER, MYBPC1, DGKB, ORC1, KLF10), disease resistance and environmental adaptability (PUS3, CRB2, CALD1, USP15, SGCD, LTBP1), as well as egg production (ADGRB3, ACSF3). Overall, native chickens in South China harbor numerous selective sweep regions compared to commercial chickens, enriching valuable genomic resources for future genetic research and breeding conservation. [ABSTRACT FROM AUTHOR]

Eggshell and shank color in poultry is an intriguing topic of research due to the roles in selection, breed recognition, and environmental adaptation. This study delves into the genomics foundations of shank and eggshell pigmentation in Italian local chickens through genome-wide association studies analysis to uncover the mechanisms governing these phenotypes. To this purpose, 483 animals from 20 local breeds (n = 466) and 2 commercial lines (n = 17) were considered and evaluated for shank and eggshell color. All animals were genotyped using the Affymetrix Axiom 600 K Chicken Genotyping Array. As regards shank color, the most interesting locus was detected on chromosome Z, close to the TYRP1 gene, known to play a key role in avian pigmentation. Additionally, several novel loci and genes associated with shank pigmentation, skin pigmentation, UV protection, and melanocyte regulation were identified (e.g., MTAP, CDKN2A, CDKN2B). In eggshell, fewer significant loci were identified, including SLC7A11 and MITF on chromosomes 4 and 12, respectively, associated with melanocyte processes and pigment synthesis. This comprehensive study shed light on the genetic architecture underlying shank and eggshell color in Italian native chicken breeds, contributing to a better understanding of this phenomenon which plays a role in breed identification and conservation, and has ecological and economic implications. [ABSTRACT FROM AUTHOR]

As a Chinese local chicken breed, Hongshan chickens have 2 kinds of tail feather phenotypes, normal and taillessness. Our previous studies showed that taillessness was a sex-linked dominant trait. Abnormal development of the tail vertebrae could be explained this phenomenon in some chicken breeds. However, the number of caudal vertebrae in rumpless Hongshan chickens was normal, so rumplessness in Hongshan chicken was not related to the development of the caudal vertebrae. Afterwards, we found that rumplessness in Hongshan was due to abnormal development of tail feather rather than abnormal development of caudal vertebrae. In order to understand the genetic foundation of the rumplessness of Hongshan chickens, we compared and reanalyzed 2 sets of data in normal and rumpless Hongshan chickens from our previous studies. By joint analysis of genome-wide selection signature analysis and genome-wide association approach, we found that 1 overlapping gene (EDIL3) and 16 peak genes (ENSGALG00000051843, ENSGALG00000053498, ENSGALG00000054800, KIF27, PTPRD, ENSGALG00000047579, ENSGALG00000041052, ARHGEF28, CAMK4, SERINC5, ENSGALG00000050776, ERCC8, MCC, ADAMTS19, ENSGALG00000053322, CHRNA8) located on the Z chromosome was associated with the rumpless trait. The results of this study furtherly revealed the molecular mechanism of the rumpless trait in Hongshan chickens, and identified the candidate genes associated with this trait. Our results will help to improve the shape of chicken tail feathers and to rise individual economic value in some specific market in China. [ABSTRACT FROM AUTHOR]

The poultry meat production landscape has undergone a reduction in chicken breeds, resulting in a reliance on a limited number of varieties. Motivated by the goal of promoting sustainable chicken production and enhancing agro-biodiversity, this study pioneers a comparison between local chicken breeds (LB) and their crossbreeds (CB) with modern hybrid lines. Serving as an initial exploration within a larger project, this research acts as a prelude to a comprehensive investigation, aiming to complement the human sensory assessment of product quality. Study I assessed chicken broths prepared from 3 German LBs Bielefelder (BIE), Altsteirer (ALT), and Ramelsloher (RAM) utilizing a factorial 3 × 2 × 2 design that incorporated variations in salt content (unsalted/salted) and cooking time (1 h/3 h). The sensory profiles of the LB broths were largely similar, except for BIE, which exhibited a higher skin odor intensity. Both, increased salt content and longer cooking time intensify sensory perception on most attributes. In study II, BIE was compared with 6 CBs, with variations in salt content and cooking time (6 × 2 × 2 + 1 × 2 factorial design). BIE demonstrated higher sensory intensities than the CBs. Those were comparable, with no clear advantages or disadvantages identified from a sensory standpoint. These findings support that crossbreeding with commercial lines is not associated with changes in the sensory profile. It thus represents a strategy for improving the economic viability of local chicken breeds in order to preserve their valuable agro-biodiversity. The provided protocol for evaluating chicken broth from LBs or their CBs aims to offer researchers a standardized foundation for sensory assessments in chicken broth studies. [ABSTRACT FROM AUTHOR]

The bird beak is mainly functioned as feeding and attacking, and its shape has extremely important significance for survival and reproduction. In chickens, since beak shape could lead to some disadvantages including pecking and waste of feed, it is important to understand the inheritance of chicken beak shape. In the present study, we firstly established 4 indicators to describe the chicken beak shapes, including upper beak length (UL), lower beak length (LL), distance between upper and lower beak tips (DB) and upper beak curvature (BC). And then, we measured the 4 beak shape indicators as well as some production traits including body weight (BW), shank length (SL), egg weight (EW), eggshell strength (ES) of a layer breed, Rhode Island Red (RIR), in order to estimate genetic parameters of chicken beak shape. The heritabilities of UL and LL were 0.41 and 0.37, and the heritabilities of DB and BC were 0.22 and 0.21, indicating that beak shape was a highly or mediumly heritable. There were significant positive genetic and phenotypic correlations among UL, LL, and DB. And UL was positively correlated with body weight (BW18) and shank length (SL18) at 18 weeks of age in genetics, and DB was positively correlated with BC in terms of genetics and phenotype. We also found that layers of chicken cages played a role on beak shape, which could be attributed to the difference of lightness in different cage layers. By a genome-wide association study (GWAS) for the chicken UL, we identified 9 significant candidate genes associated with UL in RIR. For the variants with low minor allele frequencies (MAF <0.01) and outside of high linkage disequilibrium (LD) regions, we also conducted rare variant association studies (RVA) and GWAS to find the association between genotype and phenotype. We also analyzed transcriptomic data from multiple tissues of chicken embryos and revealed that all of the 9 genes were highly expressed in beak of chicken embryos, indicating their potential function for beak development. Our results provided the genetic foundation of chicken beak shape, which could help chicken breeding on beak related traits. [ABSTRACT FROM AUTHOR]

The enclosed multistory poultry housing is a type of poultry enclosure widely used in industrial caged chicken breeding. Accurate identification and detection of the comb and eyes of caged chickens in poultry farms using this type of enclosure can enhance managers' understanding of the health of caged chickens. However, the accuracy of image detection of caged chickens will be affected by the enclosure's entrance, which will reduce the precision. Therefore, this paper proposes a cage-gate removal algorithm based on big data and deep learning Cyclic Consistent Migration Neural Network (CCMNN). The method achieves automatic elimination and restoration of some key information in the image through the CCMNN network. The Structural Similarity Index Measure (SSIM) between the recovered and original images on the test set is 91.14%. Peak signal-to-noise ratio (PSNR) is 25.34dB. To verify the practicability of the proposed method, the performance of the target detection algorithm is analyzed both before and after applying the CCMNN network in detecting the combs and eyes of caged chickens. Different YOLOv8 detection algorithms, including YOLOv8s, YOLOv8n, YOLOv8m, and YOLOv8x, were used to verify the algorithm proposed in this paper. The experimental results demonstrate that compared to images without CCMNN processing, the precision of comb detection of caged chickens is improved by 11, 11.3, 12.8, and 10.2%. Similarly, the precision of eye detection for caged chickens is improved by 2.4, 10.2, 6.8, and 9%. Therefore, more complete outline images of caged chickens can be obtained using this algorithm and the precision in detecting the comb and eyes of caged chickens can be enhanced. These advancements in the algorithm offer valuable insights for future poultry researchers aiming to deploy enhanced detection equipment, thereby contributing to the accurate assessment of poultry production and farm conditions. [ABSTRACT FROM AUTHOR]

The thymus-derived lymphocytes of jawed vertebrates have four T-cell receptor (TCR) chains that play a significant role in immunity. As chickens have commercial value, their immune systems require a great deal of attention. Local chicken breeds are an essential part of poultry genetic resources in China. Here, we used high-throughput sequencing to analyze the TCRα and TCRβ repertoires and their relative expression levels in the native chicken breeds Baier Buff, Longyou Partridge, Xiaoshan, and Xianju. We found that TCR Vα and TCR Vβ were expressed and included 17, 19, 17, and six segments of the Vα2, Vα3, Vβ1, and Vβ2 subgroups, respectively. V-J pairing was biased; Jα11 was utilized by nearly all Vα segments and was the most commonly used. Breed-specific V segments and V-J pairings were detected as well. The results of the principal coordinate analysis (PCoA) as well as the V-J pairing and CDR3 diversity analyses suggested that the four local chicken breeds did not significantly differ in terms of TCR diversity. Hence, they expressed not significant differentiation, and they are rich genetic resources for the development and utilization of immune-related poultry breeding. • Both Vα subgroups and Vβ subgroups are expressed in chicken. • Various TCR diversity with V segments, V-J pairing, and CDR3 diversity. • No significant differentiation of TCR diversity parameters among local chicken breeds. [ABSTRACT FROM AUTHOR]

In the broiler-breeding industry, phenotype determination is critical. Leg weight is a fundamental indicator for breeding, and noninvasive testing technology can reduce damage to animals. This study proposes a broiler leg weight estimation system comprising a weight-estimation model and computed tomography (CT) acquisition equipment. The weight-estimation model can automatically process the scan results of live broiler chickens from the CT acquisition equipment. The weight-estimation model comprises an improved you-only-look-once (YOLOv5) segmentation algorithm and a random forest fitting network. The segmentation head was introduced into the YOLOv5 network, combined with a multiscale attention mechanism and an atrous spatial pyramid pooling architecture, and a new network model, YOLO- measuring chicken leg weight (YOLO-MCLW), was proposed to improve segmentation efficiency and accuracy. Morphological parameters were extracted from the obtained mask image, and a random forest network was used for fitting. The experiments show that the system exhibited an average absolute error of 7.27 g and an average percentage error of 4.82% in tests on 50 individual legs of 25 broiler chickens. The prediction R 2 of broiler chicken legs can reaches 88.98%, the segmentation intersection over union result reaches 95.45%, and 37.04 images are processed per second. This system provides technical support for the part determination of broiler chickens in commercial breeding. [ABSTRACT FROM AUTHOR]

• Estimation of genetic parameters provides valuable insights into the growth and egg production traits of Korean native chicken pure lines. • High heritability values in growth traits, particularly in KNC line Y, indicate the potential for genetic improvement through performance testing. • Low heritability estimates in egg production traits highlight the importance of implementing effective management strategies to enhance productivity. • Positive correlations among growth traits suggest shared genes, indicating that genetic improvement in one trait can positively impact other correlated growth traits. • The moderate accuracy of estimated breeding values (EBVs) underscores their effectiveness as indicators of true breeding value, supporting future genetic improvement programs in Korean native chicken pure lines. Korean native chickens (KNC) have a rich history and are highly regarded by Korean consumers owing their distinct flavors and textures. However, their slow growth and limited egg production pose challenges compared with commercial chicken breeds. To address these limitations and enhance economically important traits, such as growth and egg production, understanding their genetic foundations is necessary. We studied five KNC lines (F, H, S, W, and Y) and assessed them for weight at 8, 10, and 12 weeks of age and the total number of eggs laid. The analysis incorporated pedigree data from 50773 chickens from Hanhyup Breeder chickens. Line F showed a mean inbreeding coefficient of 0.0017, whereas the other lines exhibited lower mean values ranging from 0.0005 to 0.0028, indicating that the inbreeding levels were within an acceptable range and considered safe from extinction. The average relatedness was 0.46–1.88 % among the studied lines. Heritability estimates for growth traits in line F were relatively high (ranging from 0.32 to 0.35), indicating a significant contribution of additive genetic variance and suggesting potential for genetic improvement through performance testing. However, the heritability of the egg production trait was low (0.07–0.16), indicating a greater role of non-genetic factors in explaining phenotypic variation. Management strategies should focus on improving these characteristics. Genetic correlations revealed strong positive associations between selected growth traits (up to 0.98), whereas all growth traits were negatively correlated with the total number of eggs laid. This suggests shared genetic influences on growth traits and highlights the potential for improving multiple correlated traits by enhancing the genetic performance of one trait. We also assessed the accuracy of estimated breeding values (EBVs), which ranged from 0.55 to 0.69 and 0.42 to 0.58 for growth traits and egg production trait, respectively. These moderately accurate estimates indicated that EBVs can effectively indicate the true breeding value of an animal. To improve accuracy, it is essential to maintain reliable phenotypic and pedigree records, as well as increase the number of animals in the flock. Therefore, this study provides insights into the genetic parameters and breeding value accuracy of growth and egg production traits in KNC, facilitating future genetic improvement programs for these economically important traits. [ABSTRACT FROM AUTHOR]

Salmonella has been one of the most important factors restricting the development of the poultry industry and also poses great threat to public health. To get insight into molecular alterations that occur during bacterial infection, we sequenced the cecal tonsil transcriptome in 2 chicken breeds (Beijing-You and Cobb) known to have differing resistance to Salmonella. The 28-day-old chickens were orally challenged by 1.83 × 1011 CFU Salmonella Typhimurium, and the cecal tonsil transcriptome was sequenced 3 d postinfection. Analysis identified 201 and 170 differentially expressed genes response to Salmonella in 2 chicken breeds, respectively. They were involved in the Toll-like receptor signaling pathway and activated the production of pro-inflammatory cytokines and chemokines. The protein–protein interaction (PPI) network suggested MMP9 as a crucial protein that may be involved in extracellular matrix breakdown and leukocyte migration in the resistant breed (Beijing-You). Meanwhile, in susceptible chickens (Cobb), ACOD1 was the key gene in the PPI network and might promote the expression of genes related to oxidative stress response and gastrointestinal tract function. These findings provide insight into the differing resistance of these 2 chicken breeds. [ABSTRACT FROM AUTHOR]

We compared the genomes of multiple domestic chicken breeds with red and white earlobes to identify the differentiated regions between groups of breeds differing in earlobe color. This was done using a selective sweep mapping approach based on whole-genome sequence data. The most significant selective sweep was identified on chromosome 11, where the white earlobe chicken breeds originated from Mediterranean share a common haplotype, and where multiple candidate genes are located. The most plausible functional candidate gene is the Melanocortin 1 Receptor ( MC1R ), a receptor known to regulate pigmentation in the skin and hair, and it is also the gene with the strongest positional support from the haplotype-based analyses. It, however, still needs to be explored experimentally to identify effects also on chicken earlobe color variation. Our study is the first exploration of the genetic basis of white earlobe color in Mediterranean chickens using a selective sweep mapping method based on whole-genome sequencing data and shows its value for identifying likely functional genes mediating the pigmentation in earlobe. It also indicates a potential novel role of MC1R in birds and exemplifies how selection on fancy traits has influenced the genome during formation of the modern chicken breeds. [ABSTRACT FROM AUTHOR]

Screening for genetic diversity in livestock species breeds is of utmost importance, especially for local, small populations that are at the risk of extinction. Luckily, recent developments in technology increase access to genotyping, also for numerically small breeds. One of these new technologies is the IMAGE001 single nucleotide polymorphism genotyping array that includes markers for 6 different species (cow, pig, sheep, chicken, horse and goat). For our current study, we studied the Turkey-headed Malines chicken, a local chicken breed in Belgium, for the first time. A total of 110 animals were genotyped, together with 29 samples from 4 supposedly related breeds. The genotypes were used to assess the genetic diversity of this local breed. Our analysis revealed an average inbreeding coefficient of 0.20 through runs of homozygosity analysis, and effective population size estimation based on linkage disequilibrium indicated a low genetic diversity (N e = 34). Moreover, a principal component analysis and a genetic differentiation study (F ST) were performed using these marker data to position the Turkey-headed Malines relative to the 4 other indigenous Belgian chicken breeds. Finally, we discussed the practical implications of the overlap between the IMAGE001 array and other existing chicken genotyping arrays. This study is the first use of the novel IMAGE001 array to evaluate a local chicken breed, and demonstrates it as a viable option for genomic characterization a breed. Moreover, with this research, we are able to provide a good basis for further evaluation of the Belgian chicken heritage. [ABSTRACT FROM AUTHOR]

Functional foods are innovative products that hold health-enhancing potential. They are contributing to changing trends in both consumer behavior and the market. This study was conducted to investigate the effects of breed on the nucleic acid content, amino acid profile, carcass, and meat quality of different breeds of chickens. The outcomes of which could lead to the production of functional chicken meat. In this experiment, 4 genotypes of chicken, namely commercial broilers (CBR), Thai native chickens (Mae Hong Son; MHS), Thai native chickens (Pradu Hang Dam; PHD), and male layer chickens (MLC), were fed commercial feed and reared under identical conditions. All chickens were slaughtered at the market age, whereas the breasts and thighs were separated from the carcasses to determine chemical composition and meat quality. The results indicated that carcass and meat quality traits were significantly different (P < 0.05) among chicken breeds and meat parts. Notably, commercial breeds (CBR and MLC) were superior in performance and carcass quality when compared with the Thai native chickens (MHS and PHD). CBR had the highest growth performance and carcass quality traits (P < 0.01), whereas MHS exhibited the lowest weight gain (P < 0.05). However, Thai native chickens were lower in fat, cholesterol, triglycerides, purine, and uric acid (P < 0.05) contents than the commercial breeds. Interestingly, MHS contained the lowest purine and malondialdehyde levels when compared with the other breeds (P < 0.01). Moreover, MHS contained the highest amounts of glutamic acid in both the breasts and thighs (P < 0.05). Therefore, the meat of MHS may be classified as a functional chicken meat, as it was found to have a pleasant meaty taste and hold nutritional value, which positively influences consumers' health. [ABSTRACT FROM AUTHOR]

The conservation of genetic resources is becoming increasingly important for the sustainable development of the poultry industry. In the present study, we systematically analyzed the population structure, conservation priority, runs of homozygosity (ROH) of chicken breeds globally, and proposed rational conservation strategies. We used a 600K Affymetrix Axiom HD genotyping SNP array dataset of 2,429 chickens from 134 populations. The chickens were divided into 5 groups based on their country of origin and sampling location: Asian chickens (AS-LOC), African chickens (AF), European local chickens (EU-LOC), Asian breeds sampled in Germany (AS-DE), and European breeds sampled in Germany (EU-DE). The results indicated that the population structure was consistent with the actual geographical distribution of the populations. AS-LOC had the highest positive contribution to the total gene (HT , 1.00%,) and allelic diversity (AT , 0.0014%), the lowest inbreeding degree and the fastest linkage disequilibrium (LD) decay rate; the lowest contribution are derived by European ex situ chicken breeds (EU-DE:HT = −0.072%, AT = −0.0014%), which showed the highest inbreeding and slowest LD decay. Breeds farmed in ex situ (AS-DE, EU-DE) conditions exhibited reduced genetic diversity and increased inbreeding due to small population size. Given limited funds, it is a better choice for government to conserve the breeds with the highest contribution to genetic diversity in each group. Therefore, we evaluated the contribution of each breed to genetic and allelic diversity in 5 groups. Among each group, KUR(AF), BANG(AS-LOC), ALxx(EU-LOC), BHwsch(AS-DE), and ARw(EU-DE) had the highest contribution to gene diversity in the order of the above grouping. Similarly, according to the allelic diversity standard (in the same order), ZIMxx, PIxx, ALxx, SHsch, and ARsch had the highest contribution. After analyzing ROH, we found a total of 144,708 fragments and 27 islands. The gene and genome regions identified by the ROH islands and QTLs indicate that chicken breeds have potential for adaptation to different production systems. Based on these findings, it is recommended to prioritize the conservation of breeds with the highest genetic diversity in each group, while paying more attention to the conservation of Asian and African breeds. Furthermore, providing a valuable reference for the conservation and utilization of chicken. [ABSTRACT FROM AUTHOR]

The FUNAAB Alpha broiler, a tropical chicken breed developed in Nigeria, has three genotypes which are normal feather (NF), naked neck (NN), and frizzle feather (FF). This 56-day study investigated the effect of genotype on growth, fear-related behaviours, and walking ability of FUNAAB Alpha broiler chickens. Two hundred and four (204) chickens (68 NF, 68 NN, and 68 FF chickens; 34 males and 34 females per genotype) were used for the experiment. Body weight and growth rate were measured on days 27 and 56. The level of fear using the tonic immobility test (TI) on days 23 and 51, and emergence from a dark box on days 25 and 53 were measured. Walking ability was assessed using the latency to lie test on day 54. There was a genotype effect on body weight on days 27 and 56 (p = 0.02 and p = 0.01, respectively) and growth rate from days 1–27 and days 1–56 (p = 0.02 and p = 0.03, respectively). Of the three genotypes, the NN chickens were lighter in body weight, while the NF and FF had similar body weights on days 27 and 56 (p = 0.64 and p = 0.85, respectively), and growth rate from days 1–27 (p = 0.79). The male chickens were heavier on days 27 and 56 (p = 0.04 and p = 0.04, respectively) and had a better growth rate from days 1–27 (p = 0.03). The duration of tonic immobility on days 23 and 51 was similar in all three genotypes. The latency to emerge from a dark box on day 25 was not affected (p = 0.70) by genotype, but it took the NF chickens a longer time (138.20 ± 18.70 s) to emerge from the dark box on day 53. The walking ability of the birds was not affected (p = 0.83) by the genotype. However, male chickens had better (p = 0.01) walking ability by standing for a longer time than the females during the latency to lie test. In conclusion, the NF and FF chickens were heavier than the NN on days 27 and 56, and the NN and FF chickens were less fearful than the NF chickens on day 53. The FF genotype is recommended for meat production due to its better growth and less fearfulness. [Display omitted] • FUNAAB Alpha broiler chicken is a slow-growing breed developed in Nigeria. • Naked neck and frizzle feather chickens are less fearful than normal feather chickens. • Male FUNAAB Alpha broiler chickens had a better walking ability than female chickens. • Frizzle feather chickens had a better growth performance and were less fearful. [ABSTRACT FROM AUTHOR]

Indigenous poultry breeds represent an important animal genetic resource. However, their characteristics in respect of performance, product quality, and integument condition are often poorly investigated. Therefore, the local breeds Saxonian chickens (SaChi) and German Langshan bantam chickens (GLB) of different plumage colors were characterized. The high-performing hybrid strain of Lohmann brown chickens (LB) served as the control group. For each group, 60 hens and 6 roosters were studied in an extensive free-range system from 21 to 80 wk of life. The plumage and foot pad quality were scored on 9 distinct observation dates and the measurements of the egg quality were performed at 7 different time periods. The number of eggs per hen housed in the first laying year was significantly lower in the SaChi (146.4 ± 30.8) and the GLB chickens (107.8 ± 20.4) when compared to the LB chickens (295.0 ± 16.8) (P < 0.001). Regarding laying performance, we detected effects of plumage color within both local breeds (P < 0.001). Within 4/7 plumage colors, effects of the breeder were also found (P ≤ 0.037). The eggs of the local chicken breeds showed lower egg weights (P < 0.001), shell breaking strength (P ≤ 0.041), albumen consistency (P < 0.001), and a lower egg shape index (P < 0.001), but higher proportions of yolk (P < 0.001) when compared to the eggs of the LB chickens. The logistic regression models for the plumage and footpad condition demonstrated that the SaChi and GLB hens underwent less plumage loss and footpad swelling than the LB hens (P < 0.001). Overall, this study shows that the laying performance of the local breeds was significantly lower, but there were noticeable advantages in terms of egg composition and animal welfare indicators when compared to a high-performing hybrid strain. In further studies and the use in extensive production systems, the observed performance differences between plumage colors and breeders should be taken into account. [ABSTRACT FROM AUTHOR]

The present study aims to validate the Gompertz model to predict the growth performance of chicken crosses according to growth curve parameters of the parental lines and the estimated heterosis for each curve parameter. A total of 252 one-day-old chicks of both sexes belonging to 6 genotypes, including Ross 308, Sassò (SA), Bionda Piemontese (BP), and Robusta Maculata (RM), and the crosses between these local breeds and SA (BP × SA and RM × SA) were randomly allocated in 18 pens (3 pens/genotype) in mixed-sex groups (14 animals/pen; 7 females and 7 males). The individual body weight (BW) of all birds was recorded once a week from hatching until slaughtering (81 d for Ross 308; 112 d for SA, 140 d for the other genotypes). We drew up our final dataset with 240 birds (40 birds/genotype; 20 females and 20 males). The growth curve of each genotype was described using the Gompertz model, and the heterosis for each growth curve parameter was calculated as the difference between F 1 crosses and the average of parental breeds. The predicted growth curve parameters were evaluated by cross-validation. The Gompertz model accurately estimated the growth curves of all the genotypes (R 2 > 0.90). Heterosis was significant for almost all growth curve parameters in both crosses (P < 0.05). Heterosis ranged from −13.0 to +11.5%, depending on parameters, but varied slightly between the crossbreeds (BP × SA and RM × SA). The predicted values of adult BW, weight at the inflection point, and maximum growth rate were overestimated for BP × SA and underestimated for RM × SA, with a mean error between observed and predicted values <│2.7│% for all the curve parameters. In conclusion, the growth performance of chicken crosses between local breeds and commercial strains can be accurately predicted with Gompertz parameters of the parental lines adjusting for heterosis. [ABSTRACT FROM AUTHOR]

The Korat chicken (KR) is a slow-growing Thai chicken breed with relatively poor feed efficiency (FE) but very tasty meat with high protein and low fat contents, and a unique texture. To enhance the competitiveness of KR, its FE should be improved. However, selecting for FE has an unknown effect on meat characteristics. Thus, understanding the genetic basis underlying FE traits and meat characteristics is needed. In this study, 75 male KR birds were raised up to 10 wk of age. For each bird, the feed conversion ratio (FCR), residual feed intake (RFI), and physicochemical properties, flavor precursors, and biological compounds in the thigh meat were evaluated. At 10 wk of age, thigh muscle samples from 6 birds (3 with high FCR and 3 with low FCR values) were selected, and their proteomes were investigated using a label-free proteomic method. Weighted gene coexpression network analysis (WGCNA) was used to screen the key protein modules and pathways. The WGCNA results revealed that FE and meat characteristics significantly correlated with the same protein module. However, the correlation was unfavorable; improving FE may result in a decrease in meat quality through the alteration in biological processes including glycolysis/gluconeogenesis, metabolic pathway, carbon metabolism, biosynthesis of amino acids, pyruvate metabolism, and protein processing in the endoplasmic reticulum. The hub proteins of the significant module (TNNT1, TNNT3, TNNI2, TNNC2, MYLPF, MYH10, GADPH, PGK1, LDHA, and GPI) were also identified to be associated with energy metabolism, and muscle growth and development. Given that the same proteins and pathways are present in FE and meat characteristics but in opposite directions, selection practices for KR should simultaneously consider both trait groups to maintain the high meat quality of KR while improving FE. [ABSTRACT FROM AUTHOR]

Chicken is a major source of protein for the increasing human population and is useful for research purposes. There are almost 1,600 distinct regional breeds of chicken across the globe, among which a large body of genetic and phenotypic variations has been accumulated due to extensive natural and artificial selection. Moreover, natural selection is a crucial force for animal domestication. Several approaches have been adopted to detect selection signatures in different breeds of chicken using whole genome sequencing (WGS) data including integrated haplotype score (iHS), cross-populated extend haplotype homozygosity test (XP-EHH), fixation index (F ST), cross-population composite likelihood ratio (XP-CLR), nucleotide diversity (Pi), and others. In addition, gene enrichment analyses are utilized to determine KEGG pathways and gene ontology (GO) terms related to traits of interest in chicken. Herein, we review different studies that have adopted diverse approaches to detect selection signatures in different breeds of chicken. This review systematically summarizes different findings on selection signatures and related candidate genes in chickens. Future studies could combine different selection signatures approaches to strengthen the quality of the results thereby providing more affirmative inference. This would further aid in deciphering the importance of selection in chicken conservation for the increasing human population. [ABSTRACT FROM AUTHOR]

Innate immunity is the first line against the invasion of pathogenic microorganisms. Previous reports only demonstrated production traits of commercial importance were often negatively correlated with innate disease resistance. However, whether different purpose of artificial selection influences innate immunity have not been understood. In this study, we cloned exon1, exon6 of IFIH1 and exon2 of IFIT5 by molecular biology techniques in seven different chicken breeds to detect the potential effect of artificial selection for commercial traits on disease resistance for the first time. In total, 8 single nucleotide polymorphisms(SNPs) of IFIH1 gene exon1 and exon6, 19 SNPs of IFIT5 gene exon2 were detected. We found all native chicken breeds had a relatively close relationship to broiler breeds but a remote relationship to layer breed. A great difference between CB and LLH with different selected purpose were observed. The allele frequencies of these two positive antiviral genes were associated with different purpose of artificial selection. Our experiment constituted the foundation for the interaction between commercial traits and immune trait. [ABSTRACT FROM AUTHOR]

In hens, egg production depends on the development of germ cells in the ovary. Germ cells are established before birth, and their number gradually decreases during their lifespan. Therefore, it is essential to determine the time points of massive germ cell loss and the underlying mechanism. In this study, a gene-edited chicken with mCherry fluorescence specifically expressed in the germline was generated by the integration of the mCherry gene into the 3'-end of the DAZL locus, which facilitated the isolation of germ cells from the gonads of DAZL–mCherry embryos or chicks and quantification using flow cytometry based on the observation of red fluorescence. The results demonstrated the dynamics of germ cell development from embryos at 17 d of hatching (dh) to chickens at 7 d post-hatch (dph) and revealed a substantial loss of germ cells in the late embryonic stage (18 –19 dh) and post-hatch period (2 –3 dph). Additionally, the number of germ cells in DAZL × Guangxi Ma chicken was significantly higher than that in DAZL × Lohmann Pink chicken at 19 dh and 3 dph (P < 0.05). Furthermore, the numbers of germ cells positively correlated with the body weight in DAZL × Lohmann Pink chicken. In conclusion, our results showed the dynamics of germ cell development in chicken ovaries during peri-hatch periods and indicated the time point of substantial germ cell loss. The results provide evidence for further exploration of the underlying mechanism and serve as a reference for chicken breeding and management. [ABSTRACT FROM AUTHOR]

• New method for generating growth and degrowth models. • Generalization of the mathematical method proposed by Santos et al. (2019). • New unicompartimental model for fitting the Athens-Canadian Random Bred cockerels data. This paper aims to propose a new method for generating growth and degrowth models. To do so, the composition operation was added to the method proposed by Santos et al. (2019). From this new method, the model proposed by the composition of von Bertalanffy with Brody was created. The proposed model was compared to other unicompartmental models already described in the literature. The evaluated models were: Logistic, Brody, von Bertalanffy, Gompertz, Richards and the Proposed one. The following evaluators were used to define the best model.: the adjusted coefficient of determination R a j. 2 , mean squares residual (MSR), Akaike Information Criterion (AIC), Mean Absolute Deviation of the residues (MAD), Bayesian information criterion (BIC), Penalizing adaptively the Likelihood (PAL) and Predictive ability of the model (ρ). The Proposed model was the most adequate to fit to the Athens-Canadian male chickens data. Thus, this work contributed, adding the composition operation. Furthermore, the model generated by this method is effective for fitting the Athens-Canadian chicken breed data. [ABSTRACT FROM AUTHOR]

Abdominal fat is the major adipose tissue in chickens. In chicken, the deposition of abdominal fat affects meat yield and quality. Previous reports suggest that gut microbiota composition and function are associated with lipid metabolism. In this study, we used comparative metagenomics and metabolomics analysis to determine the gut microbiota and gut-host metabolite profiles in Shouguang (SG ; a Chinese chicken breed with low-fat deposition) and Luqin (LQ ; a fatty-type chicken breed with a fast growth rate) chickens. The results showed that LQ chickens had higher body weight, eviscerated yield, abdominal fat yield, abdominal fat ratio, and triglyceride (TG) content in the breast muscle than SG chickens. Untargeted metabolomics analyses showed a total of 11 liver metabolites, 19 plasma metabolites, and 30 cecal metabolites differentially enriched in LQ and SG chickens based on variable importance in the projection (VIP) ≥ 1 and P ≤ 0.05. These metabolites are involved in lipid and amino acid metabolism. The relative abundance of bacteria in the microbiota differed significantly between the 2 chicken breeds. The functional prediction of microbiota abundant in LQ chickens was starch and lactose degradation. Erysipelatoclostridium was abundant in LQ chickens and significantly positively correlated to palmitoyl ethanolamide (PEA), a key regulator of lipid metabolism. Our findings revealed differences in liver and plasma metabolites between chicken breeds with different adipose deposition capacities. Long-chain acylcarnitines might be important markers of adipose deposition differences in chickens. The cecum's microbial communities and metabolome profiles significantly differed between LQ and SG chickens. However, the relationship between cecal microbiota and their metabolites and liver and plasma metabolites is not thoroughly understood. Future research will focus on relating tissue metabolite changes to intestinal microbiota and their effects on body fat deposition. [ABSTRACT FROM AUTHOR]

• Selection-driven chicken phenome embraces varied phenotypes including pectoral angle. • We studied PA variation across divergently selected chicken breeds. • Patterns of PA relationship with performance traits were analysed. • We propose a promising PA-based auxiliary index for using in layer selection. An appreciation of the synergy between genome and phenome of poultry breed is essential for a complete understanding of their biology. Phenotypic traits are shaped under the influence of artificial, production-oriented, selection that often acts contrary to that which would occur during natural selection. In this comparative study, we analysed the phenotypic diversity of 39 chicken breeds and populations that make up a significant part of the world gene pool. Grouping patterns of breeds found within the traditional, phenotypic models of their classification/clustering required in-depth analysis using sophisticated mathematical approaches. As a result of studying performance and conformation phenotypes, a phenomenon of previously underestimated variability in pectoral angle (PA) was revealed. Moreover, patterns of PA relationship with productive traits were analysed. We propose using PA measurement as a promising new auxiliary index for selecting hens and roosters of breeding flocks in egg production improvement programs. [ABSTRACT FROM AUTHOR]

• The influence of maternal effects on offspring phenotype was significant. • Genetic correlations between direct and maternal genetic were negative. • Estimates of heritability were low for relative growth rates. • Heritability Estimates were low to moderate for growth efficiencies and Kleiber ratios. The aim of this study was to investigate the genetic and phenotypic aspects of growth efficiency-related traits in Mazandaran native chickens. For this purpose, phenotypic and pedigree data of 21 generations were obtained from Mazandaran native chicken breeding center. Studied traits included Kleiber ratio (KR), relative growth rate (RGR) and growth efficiency (EF) at different growth phases from hatch to 8 weeks of age (1-8), hatch to 12 weeks of age (1-12), 8 weeks to 12 weeks of age (8-12), hatch to sex maturity (1-SM), 8 weeks of age to sex maturity (8-SM) and 12 weeks of age to sex maturity (12-SM). Genetic parameters and (Co) variance components were estimated by Restricted Maximum Likelihood (REML) procedure under six different univariate animal models using WOMBAT software with and without considering the maternal effects. Based on the results of the best model, determined by the Akaike Information Criterion (AIC), the estimates of direct heritability ranged from 0.05 (EF8-12) to 0.32 (EF12-SM) for growth efficiency, from 0.06 (KR8-12) to 0.37 (KR8 -SM) for Kleiber ratios and from 0.06 (RGR8-12) to 0.16 (RGR1-12) for relative growth rates. Maternal heritability ranged from 0.03 (EF8-12, EF1-8) to 0.08 (EF1-SM) for growth efficiency, from 0.006 (KR8-12) to 0.097 (KR1-SM) for Kleiber ratios and form 0.03 (RGR8-12) to 0.14 (RGR1-12) for relative growth rates. Negative genetic correlations between direct and maternal additive genetic effects were estimated for all studied traits. In conclusion, significant maternal effects indicated that these effects should be considered in genetic evaluation of traits. [ABSTRACT FROM AUTHOR]

Animal welfare is of general interest, and in the farming arena, efforts have increased to create optimal conditions for poultry production. Detailed and standardized studies on specific behavioral issues, such as fear, exploration, and social reinstatement behavior, are needed to support these initiatives. The variables mentioned can be directly queried from the animal in the open field to provide information on welfare-related behavioral traits, such as general fearfulness and balanced emotionality. Animal genetic resources help us get an insight into the possible diversity of behavioral responses. The majority of these responses can be identified as breed-specific and thus genetically correlated, providing a starting point for future breeding objectives. The behavioral responses of a chicken can be related to the breeding history of the population or to the experience gained during its lifetime. Both may go hand in hand to enable the animal to adapt to its environment, contributing to animal welfare. [ABSTRACT FROM AUTHOR]

This study examines the effect of the presence of hens on sperm variables in Black Barred Andaluza roosters (which respond well to the massage technique). Between 8 and 22 weeks of age, roosters (n = 60) were housed separate from hens in straw litter pens (4 birds/m²). Two groups of roosters were then formed to study the effect of hen presence on sperm variables at 36 weeks of age. The first group (n = 11 roosters) was housed with hens (n = 55; sex ratio 1:5), while the second (n = 27 roosters) was again housed separate from hens. Twenty four sperm pools were obtained over 12 weeks (12 pools from each group, each pool produced by mixing semen from 11 males) for analysis. Compared to the no-female-contact group, the roosters living with hens showed significantly (P < 0.05) reduced percentages of non-progressive motile sperm and slow sperm, and significantly increased VCL and VSL values; they also showed trends (P < 0.1) towards increased progressive motility and a higher percentage of rapid sperm. The presence of hens had no significant effect on the number of spermatozoa per ejaculate or sperm concentration. Positive correlations were recorded between VSL and VCL, and between both of these and progressive motility, and the percentage of rapid sperm. In addition, both VSL and VCL correlated negatively with non-progressive motility and the percentage of slow sperm. These results indicate that rooster sperm quality, but not quantity, improves in the presence of hens. [ABSTRACT FROM AUTHOR]

Pullorum disease is characterized by white diarrhea resulting from infection by S. Pullorum, but arthritis associated with S. Pullorum infection has become increasingly frequent recently, especially in Chinese native chicken flocks. In this study, we isolated and identified 4 S. Pullorum strains from the Qingjiaoma chicken breeders with arthritis symptoms. The LD 50 of the isolate 20JS04 was 1.33 × 106 CFU, which was considered as a highly virulent strain in chicks. Reproducible arthritis symptoms were observed in the experimentally chickens infected with the isolate 20JS04, and the disease occurrence was 27.78% (5/18). In addition to the characteristics of high virulence and induced-arthritis, our results confirmed that the arthritis-causing isolate 20JS04 had greater negative impact on BW, ADFI, and ADG, compared with the white diarrhea-causing S. Pullorum standard strain CVCC526 (P < 0.05). These results suggest that the pathogenic diversity of S. Pullorum in China deserves more attention and stringent measures should be taken to control salmonellosis. [ABSTRACT FROM AUTHOR]

A trial was conducted to compare muscle traits and meat quality characteristics of the pectoralis muscle in 2 chicken commercial hybrids having standard (SBY) and high breast yield (HBY), respectively. A total of 2,124 one-day-old male chicks, equally divided into 2 experimental groups represented by strains (SBY and HBY), were grown using homogenous conditions and fed the same standard diets until reaching live weight of 4.2 kg at 53 and 55 d for the SBY and HBY groups, respectively. Thirty-six birds per each genotype were randomly selected, and their pectoralis major muscles were used to assess meat quality properties (color attributes, pH. drip loss, cook loss, Allo-Kramer shear values after cooking, moisture, proteins, total lipids, and ashes) as well as histological traits (cross-sectional area, frequency of abnormal fibers, and intramuscular fat infiltration). As expected, HBY genotype had higher breast yield (31.0 vs. 30.0%; P ≤ 0.05). Histological evaluations showed that HBY pectoralis muscles had higher cross-sectional fiber area coupled with a dramatically higher (P ≤ 0.001) incidence of abnormal fibers and more abundant infiltration of intramuscular fat. Moreover, histopathological anomalous features such as central nuclei, proliferation of endomysial and perimysial collagen, inflammatory infiltrate, and necrosis of the fibers were also observed. As for meat quality, SBY hybrid showed lower ultimate pH values (5.97 vs. 6.07; P ≤ 0.01), whereas overall color parameters were not affected by genotype. Breast meat from the HBY genotype also exhibited significantly lower ability to retain liquid during refrigerated storage (drip loss, 2.46 vs. 2.06%; P ≤ 0.05) and cooking (26.2 vs. 21.1%; P ≤ 0.05) as well as higher shear-force values (2.59 vs. 2.11 kg/g; P ≤ 0.001). Finally, with regard to chemical composition, significant differences (P ≤ 0.05) were detected in protein (22.8 vs. 23.5%) and lipid (1.65 vs. 1.82%) contents, which were significantly lower in the HBY hybrid, whereas moisture content tended (P = 0.07) to be inferior in the SBY hybrid. [ABSTRACT FROM AUTHOR]

The study aimed to characterize muscle fiber type of the pectoralis major muscle of slow-growing chickens belonging to the Padovana local breed, the commercial strain Berlanda gaina, and their cross. Forty-five chickens (both males and females) from the different genotypes were grown up to 180 d. Histochemical and morphometrical analyses were performed to characterize muscle fiber types, myofiber density, and myofiber size of the different genotypes. The effects of genotype, sex, and their interaction were estimated. Muscle samples appeared almost entirely made up of IIB fiber type, whereas a low percentage of area (5 to 6%) was composed of hypercontracted fiber. Myofiber density was significantly higher (P < 0.05) in Padovana strains and cross-sectional area was significantly lower (P < 0.01) than in Berlanda strain. Muscle fiber characteristics appeared not to be affected by the interaction of genotype x sex. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of breed, sex, and age on the gene expression level of melanocortin 1 receptor (MC1R), DOPA chrome tautomerase (DCT), tyrosinase-related protein 1 (TYRP1), tyrosinase (TYR), and agouti signaling protein (ASIP) genes in Thai commercial chicken lines. All chicken have received Newscastle vaccination, and no antibiotics or any drugs were used in this study. Four chicken breeds including Black-Chinese, KU-Phuparn, Sri Mok, and Pradu Hang Dam were used in this study. These breeds can be classified by their skin color into 3 group including black (Black Chinese and KU-Phuparn), light black (Sri Mok), and yellowish white (Pradu Hang Dam). One hundred chickens per breed were used in this study. Breast skin tissue was randomly collected from 8 chickens (4 males, 4 females) per breed at 4, 8, 12, and 16 wk of age. The mRNA expression was analyzed using qRT-PCR and the gene expression level was calculated as 2−ΔΔCT. From the results, breed significantly (P < 0.01) affected the expression level for the 5 genes evaluated. Birds with the black skin color had greater TYRP1 and TYR gene expression when compared to chickens with light black and yellowish-white skin color, respectively. Whereas, chickens with yellowish-white skin color had greater ASIP gene expression when compared to chickens having the other skin colors. Sex significantly affected DCT, TYRP1, and TYR gene expression where the gene expression in males was greater when compared to females (P < 0.05). Age affected all gene expression levels (P < 0.01). At 4 wk of age, MC1R, DCT, TYRP1, and TYR gene expression was the highest and decreased as bird age increased (P < 0.05); however, ASIP gene expression was greatest at 8 wk of age. After 8 wk of age all gene expression for the genes evaluated in this study decreased as age increased. In addition, an interaction between breed and sex (P < 0.05) impacted DCT and ASIP gene expression. The results from this study showed that all genes evaluated can be used as candidate markers to further improve the blackness of the chicken's skin because the most desired skin color is black in the Thai black-bone chicken population. [ABSTRACT FROM AUTHOR]

Abstract: STAT5A/B proteins are the important modulators of growth hormone, growth hormone receptor, IGF-I, prolactin and insulin signaling pathway, which are involved in growth and reproduction. Knowledge of genetic markers in such candidate genes and their association with economical traits, probably make breeding plans more efficient through MAS programs. The aim of the current study was to investigate the possible association of two SNP in chicken STAT5B gene with breeding value of growth and reproductive traits. Total of 205 individuals from breeding station of Mazandaran Indigenous Chicken were selected randomly and they were genotyped for two SNPs of C4535156T and G4533675C using PCR-RFLP technique and HhaI and RsaI restriction enzymes respectively. To estimate breeding value of the growth and reproductive traits, phenotypic information of 18 successive generations of selection in breeding station of Mazandaran Indigenous Chicken (north of Iran) was analyzed using a univariate animal model in ASREML procedure. Finally, marker-trait association analyses were performed using estimated breeding value of the traits, as dependent variable, in GLM procedure of SAS 9.1. Two alleles and three genotypes were identified for each SNP. Significant associations between C4535156T SNP with breeding value of body weight at hatch and between G4533675C SNP with breeding value of first egg weight were found. We can conclude that two SNPs in STAT5B gene are promising markers for future use in selection to increase body weight at hatch and first egg weight. [Copyright &y& Elsevier]

The present study was conducted to characterize 2 important native chicken breeds from India and compare them on growth, .production, egg and semen quality, and welfare traits. The Aseel breed showed (P < 0.001) higher BW at different ages; higher shank, radius, and toe lengths at 40 wk of age; and greater egg weights at 28, 32, and 40 wk of age than did the Kadaknath breed. The Kadaknath breed reached sexual maturity at an early age, and it had higher 40-wk egg production (P < 0.001). Higher egg specific gravity (P < 0.05) and higher albumen (P < 0.00 1) and shell (P < 0.009) percentages in the Kadaknath were observed, whereas the Aseel breed had a higher yolk index (P < 0.004), higher yolk percentage (P < 0.001), and higher yolk-to-albumen ratio (P < 0.001). Concentration of sperm (P < 0.01), live sperm counts (P < 0.05), and semen appearance scores (P < 0.05) were higher in the Aseel breed than in the Kadaknath breed. The Aseel breed showed a greater incidence of feather-pecking behavior under floor rearing, and this was negligible or mild in the Kadaknath breed. Broodiness under cage rearing was observed (8.42%) in the Aseel breed. With regard to welfare traits, male Aseel birds had a significantly shorter (P < 0.05) duration of tonic immobility (TI) than did male Kadaknath birds. Furthermore, male Aseel birds had a shorter (P < 0.001) duration of TI than did female Aseel birds, whereas female Aseel birds had a longer (P < 0.05) duration of TI than did female and male Kadaknath birds. From this study, it was concluded that the breeds differed on various growth, production, egg and semen quality, and behavioral traits, but not on welfare traits, although female Aseel birds exhibited a greater fear response. [ABSTRACT FROM AUTHOR]

The identification and utilization of potential candidate genes for QTL with significant effects on economically important traits are becoming increasingly important in poultry breeding programs.. Chicken insulin-like growth factor binding protein 1 and 3 and signal transducers and activators of transcription 5B (STAT5B) genes are 3 essential nodes for signaling pathways and gene networks of growth and reproduction. The pooled DNA sequencing approach was used for identification of 9 S.NP of the 5' upstream region of the 3 genes. A total of 826 individuals from Beijing You chicken were genotyped for 5 SNP using a modified PCR-RFLP method and the association with chicken growth and reproductive traits was studied using the GLM procedure. The T56039403C (T- 808C) SNP of the insulin-like growth factor binding protein 1 gene .was associated with BW at 10 wk of age (P 0.0061), and the C56072547T (C-968T) SNP of the insulin-like growth factor binding protein 3 gene was associated with BW at 8 and 10 wk of age (P = 0.0056 anl. P = 0.0016, respectively). The C4535156T (C-1591T), G4533815A (G-250A), and G4533675C (G-110C) SNP of the STAT5B gene were associated with age at first egg (P = 0.0143, P = 0.0088, and P = 0.0114, respectively). Moreover, Lewontin's D' (ID'I) and r² of C4535156T and G4533815A SNP, C4535156T and G4533675C SNP, and G4533815A and G4533675C SNP of the STAT5B gene were 0.939 and 0.852, 0.967 and 0.858, and 0.971 and 0.896, respectively. The 3 SNP were strong-linked with each other and lay within a haplotype block. Our results suggest that these SNP were significantly associated with early growth or with sexual maturation in chickens, or both, and may be potential molecular markers for MAS. [ABSTRACT FROM AUTHOR]

• We tested predator behavior that could shape the diversity of warning signals. • We measured innate avoidance and learning in quail and two breeds of chicken. • The innate response to blue but not orange varied among the three predator types. • Blue was learned less effectively than orange in some predator types. • Chicken breeds should be carefully considered in warning color experiments. Warning coloration deters predators from attacking unpalatable prey, and is often characterized by long-wavelength colors, such as orange and red. However, warning colors in nature are more diverse and include short-wavelength colors, like blue. Blue has evolved as a primary defense in some animals but is not common. One hypothesis for the maintenance of this diversity is interspecific variation in predator responses to signals. We tested this hypothesis with galliform birds: Gambel's quail (Callipepla gambelii) and two domestic chicken breeds (Gallus gallus domesticus; Plymouth Rocks, Cochin Bantams). We measured innate avoidance and learning responses to only blue prey, only orange prey, and orange-and-blue prey, where the blue was iridescent to represent the natural coloration of the pipevine swallowtail butterfly (Battus philenor). We predicted birds would have similar responses to orange, but vary in response to blue. Upon first encounter, Cochin Bantams did not attack blue and Gambel's quail readily attacked, indicating innate avoidance by Cochin Bantams. Plymouth Rocks had no innate aversion to any color, lower attack latencies and attacked most prey items. Cochin Bantams and Gambel's quail both learned orange and orange-and-blue quicker than blue. Our results support the hypothesis that interspecific variation in predator response could maintain warning color diversity. [ABSTRACT FROM AUTHOR]

Dodoma's population is growing rapidly creating a high demand for food security like chicken products. However, the distribution of chickens' management systems, breed of chicken kept, and challenges facing chicken production in Dodoma are less documented. This study focused on finding out the productivity of chicken in terms of flock size and how it is affected by the management system, types/breed of chicken keeping, and evaluating the challenges facing chicken production in Dodoma. A cross-sectional survey using a semi-structured questionnaire was used to generate data from the two randomly selected districts namely, Kongwa and Dodoma Municipal. The results showed that the average flock size was significantly (P < 0.0001) higher in Dodoma municipal (mean = 124.56 ± 35.08, n = 200) than in Kongwa district (mean = 42.55 ± 5.54, n = 200). Broiler and layers keeping under the intensive system were dominant in Dodoma municipal while local breed chicken under the free-range system was dominant in Kongwa district (P < 0.001). Diseases were the main challenge facing chicken production. It was eminent that, diseases and other challenges such as theft, predation, lack of experts, unavailable space and huts for keeping chicken, and insufficient feed staffs for chicken significantly lowered the chicken production in Dodoma (P < 0.05). It is conclusive that, the demand for chicken products in Dodoma is higher and will continue to increase. There is a need for chicken keepers to increase production to overcome the current deficit. The increases in production should go hand in hand with solving the challenges which face chicken production in Dodoma. [ABSTRACT FROM AUTHOR]

The influence of broodiness on egg production was evaluated, and correlations between the age of the first broody cycle (AFB), duration of first broody cycle, and interval between the end of the first broody cycle and the re-laying of eggs were calculated in Chinese Qingyuan (Q line) chicken. In addition, age at first egg and individual egg production were recorded. From a single hatch, hens were randomly divided into 2 groups, group A (n 576) and group B (n = 576). Group A hens were allowed to go through the entire broody cycle, whereas group B hens were treated so as to interrupt the cycle. Mean incidence of broodiness was approximately 15%, with the average AFB at approximately 40 wk (i.e., about 20 wk after the onset of lay). Nonbroody hens produced more eggs than broody and treated hens. However, a higher laying rate during the nonbroody period partially compensated the egg loss from broodiness. Negative correlations (P < 0.01) were found between AFB and duration of first broody cycle or interval between the end of the first broody cycle and the re-laying of eggs, indicating that the age of the first broody cycle can be regarded as a phenotypic marker for intensity of broodiness in hens. [ABSTRACT FROM AUTHOR]