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Simple Summary: The genetic polymorphisms in the ovocalyxin-32 gene were studied in the present work with regard to egg quality traits in indigenous chicken populations. In the same investigation, based on exons 1 and 6, the frequencies of G/T and A/G SNPs regarding the Hardy–Weinberg equilibrium (HWE) and their role in egg quality were determined. The T allele of the G/T SNP in exon 1 was associated with thinner shells and lower shell strength, while the A/G SNP in exon 1 resulted in eternal eggs with thicker shells in AG and AA genotypes. Regarding this, the A/G SNP in exon 6 was able to enhance shell and yolk quality in AG genotypes. These SNPs could be considered candidate genetic markers for marker-assisted selection (MAS) focusing on egg quality improvement, which has additive and dominance genetic effects on phenotypic variation. This study sought to evaluate the genetic variations of the ovocalyxin-32 gene and its association with egg quality traits in indigenous chicken populations, focusing on exons 1 and 6. Genotype frequencies of SNPs (G/T and A/G) within these exons were assessed for their conformity to the Hardy–Weinberg equilibrium (HWE) across several strains. While most strains exhibited close adherence to HWE expectations, some like light-brown and gray strains indicated substantial discrepancies, particularly for the TT genotype, which points towards the possible effects of genetic drift as well as selection pressures. This study also analyzed the influence of such SNPs on egg quality parameters. A thinner eggshell, reduced shell weight, and decreased breaking strength were associated with the G/T SNP in exon 1, suggesting a likely negative effect on egg quality in T allele carriers. Conversely, the AG genotype displayed better performance in shell thickness, weight and egg weight in the A/G SNP in exon 1, whilst yolk height was best improved by the AA genotype compared to breaking strength. For instance, in exon 6, the A/G SNP enhanced the shell and yolk quality among AG genotypes, while the CC genotype resulted in better eggshell characteristics with enlarged yolks because the C/T SNP was linked. Nonetheless, there were no significant deviations from the HWE despite these associations, which suggested that most breeds had a stable genetic background. Further, considering SNPs' additive and dominant effects in this research, it was indicated that additive effects account for phenotypic expressions given by the G/T SNP located at exon 1. In contrast, significant additive and dominant effects were observed under the A/G SNP situated at the exon. Generally, it therefore could be concluded from this study that specific SNPs within the ovocalyxin-32 gene may act as good markers for marker-assisted selection (MAS) that can improve desired characteristics—such as those of egg quality—in indigenous chicken breeds. This study demonstrated that both additive and dominance effects must be taken into account when performing genetic analyses, thereby emphasizing the complexity of phenotypic variation caused by genetic mechanisms in native chicken races. [ABSTRACT FROM AUTHOR]

Native chickens in Ethiopia are characterized in a fragmented manner for their performance characteristics and genotypes. This review aimed to explore the production and reproduction performance characteristics as well as the morphometric and morphological diversity of Ethiopian native chickens. The investigation was performed on four production performance characteristics, including average egg per clutch, average clutch/hen/year, average egg set/hen, and average egg/hen/year, as well as six reproductive performance characteristics, including age at first laying, age of male chickens at first bred, age at which female chickens are first bred, the reproductive life span of males and females, and fertility percentage in various parts of Ethiopia. Some economically practical morphometric characteristics of native chickens, such as shank length, chest circumference, comb length, body weight, body length, keel length, wattle length, neck length, back length, and morphological diversity, were also summarized. Regarding performance characteristics, there were some variations in eggs’ average production performance per clutch (13.56-15.4 eggs) and clutch/hen/year (3.0-4.29) in Ethiopia. The average reproduction performance characteristics of Ethiopian native chickens for age at first laying (6.90-7.13 months), age of male chickens at first bred (5.87-6.15 months), female at first bred (5.20-5.93 months), the reproductive life span of males (3.79 years) and hens (3.56 years), and chicks hatched from set eggs revealed variation across Ethiopia. In various locations of Ethiopia, the average trait values reported for Ethiopian native chickens under the farmer’s management differed in terms of morphometric and morphological features. The variation observed in performance characteristics, as well as morphometrics and morphological characteristics for Ethiopian native chicken ecotype population, can help the native breed classification, unique trait conservation, and breed improvement intervention programs. [ABSTRACT FROM AUTHOR]

The native breed of chicken is one of the most income-producing species in the poultry sector in the Egyptian governorate of Ismailia. Thus, the objective of the current study was to identify the collected parasites using a light microscope and estimate the prevalence and seasonal dynamics of the collected helminths using the newly introduced molecular biology methods. 120 chickens out of 170 recorded (70.59%) prevalence of helminth infestation during the period from September 2021 until the end of August 2022. Four nematodes with a prevalence of 44.12 %, which were Ascaridia galli, Heterakis gallinarum, Subulura brumpti, Trichostrongylus tenuis, and four cestodes with 26.47 %, which were Raillietina tetragona, R. echinobothrida, Hymenolepis carioca, and Choanotaenia infundibulum. Eimeria spp. infestation (11.18%), which were E. tenella, E. maxima, E. mitis, and E. brunetti. Ectoparasites (15.88%) were Echidnophaga gallinacea, Lipeurus caponis, Menopon gallinae, Columbicola columbae, and Dermanyssus gallinae. The identities of the certainly recovered nematode and cestode species were confirmed by the blast test using DNA sequence data. Thus, it is advised to use the molecular approach as the primary methodology for the accurate identification of helminths, particularly in closely related species. [ABSTRACT FROM AUTHOR]

The study was carried out to investigate the carcass and meat quality traits and nutritional profile of the meat of the Kadaknath, a unique native chicken breed in comparison with commercial broilers. The yield of the carcass, breast and giblets of the Kadaknath was lesser (p < 0.01), while that of the legs, wings, back, and neck was higher (p < 0.01) than broilers. The meat of the Kadaknath was significantly (p < 0.0001) darker (42.44, 50.92) and more yellow (6.23, 8.99) than broilers. The decline in pH of the meat was lower (p < 0.001) in the Kadaknath compared to broilers. Kadaknath meat had more protein and less fat, moisture and ash content than broilers (p < 0.01). Furthermore, it was richer (p < 0.01) in 11 amino acids, including those which are known to impart a sweet and umami taste, than the meat of broilers (3 amino acids). Both genotypes were almost similar in meeting the daily requirements of indispensable amino acids of adult human. The study concluded that the Kadaknath differed in carcass and meat quality characteristics from the broilers, and the nutritional quality of Kadaknath meat in terms of high protein and less fat and higher content of amino acids (tasty type) was better in Kadaknath meat as compared to broiler meat. [ABSTRACT FROM AUTHOR]

The quality and flavor of chicken are affected by muscle metabolites and related regulatory genes, and the molecular regulation mechanism of meat quality is different among different breeds of chicken. In this study, 40 one-day-old Daweishan mini chicken (DM) and Cobb broiler (CB) were selected from each group, with 4 replicates and 10 chickens in each replicate. The chickens were reared until 90 d of age under the same management conditions. Then, metabolomics and transcriptomics data of 90-day-old DM (n = 4) and CB (n = 4) were integrated to analyze metabolites affecting breast muscle quality and flavor, and to explore the important genes regulating meat quality and flavor related metabolites. The results showed that a total of 38 significantly different metabolites (SDMs) and 420 differentially expressed genes (DEGs) were detected in the breast muscle of the 2 breeds. Amino acid and lipid metabolism may be the cause of meat quality and flavor difference between DM and CB chickens, involving metabolites such as L-methionine, betaine, N6, N6, N6-Trimethyl-L-lysine, L-anserine, glutathione, glutathione disulfide, L-threonine, N-Acetyl-L-aspartic acid, succinate, choline, DOPC, SOPC, alpha-linolenic acid, L-palmitoylcarnitine, etc. Important regulatory genes with high correlation with flavor amino acids (GATM, GSTO1) and lipids (PPARG, LPL, PLIN1, SCD, ANGPTL4, FABP7, GK, B4GALT6, UGT8, PLPP4) were identified by correlation analysis, and the gene-metabolite interaction network of breast muscle mass and flavor formation in DM chicken was constructed. This study showed that there were significant differences in breast metabolites between DM and CB chickens, mainly in amino acid and lipid metabolites. These 2 kinds of substances may be the main reasons for the difference in breast muscle quality and flavor between the 2 breeds. In general, this study could provide a theoretical basis for further research on the molecular regulatory mechanism of the formation of breast muscle quality and flavor differences between DM and CB chickens, and provide a reference for the development, utilization and genetic breeding of high-quality meat chicken breeds. [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]

The acute thermal response has been extensively studied in commercial chickens because of the adverse effects of heat stress on poultry production worldwide. Here, we performed whole-genome resequencing of autochthonous Niya chicken breed native to the Taklimakan Desert region as well as of 11 native chicken breeds that are widely distributed and reared under native humid and temperate areas. We used combined statistical analysis to search for putative genes that might be related to the adaptation of hot arid and harsh environment in Niya chickens. We obtained a list of intersected candidate genes with log2 θπ ratio, FST and XP-CLR (including 123 regions of 21 chromosomes with the average length of 54.4 kb) involved in different molecular processes and pathways implied complex genetic mechanisms of adaptation of native chickens to hot arid and harsh environments. We identified several selective regions containing genes that were associated with the circulatory system and blood vessel development (BVES, SMYD1, IL18, PDGFRA, NRP1, and CORIN), related to central nervous system development (SIM2 and NALCN), related to apoptosis (CLPTM1L, APP, CRADD, and PARK2) responded to stimuli (AHR, ESRRG FAS, and UBE4B) and involved in fatty acid metabolism (FABP1). Our findings provided the genomic evidence of the complex genetic mechanisms of adaptation to hot arid and harsh environments in chickens. These results may improve our understanding of thermal, drought, and harsh environment acclimation in chickens and may serve as a valuable resource for developing new biotechnological tools to breed stress-tolerant chicken lines and or breeds in the future. [ABSTRACT FROM AUTHOR]

The biological experiment was designed to study the effect of feeding ghee residue in native chicken (Aseel) for a period of 12 weeks on various parameters, viz. bi-weekly body weight, gain in body weight, feed consumption, feed conversion ratio, livability and the cost effectiveness of feeding ghee residue. A total of 300 day-old, unsexed, Aseel native chicken belonging to single hatch were utilized for this study. The treatment groups were fed with diets containing ghee residue at different inclusion levels, i.e. 0% (T1-control), 5% (T2), 10% (T3) and 15% (T4). Biological experiment revealed that there was significant difference in body weight and body weight gain and feed conversion ratio and no significant difference was observed in feed consumption and livability. The cost effectiveness of the native chicken fed with various levels of ghee residue showed increased net profit per kg live weight in the group fed 5% ghee residue. [ABSTRACT FROM AUTHOR]

Domestic chickens (Gallus gallus) play a significant role, ranging from food and entertainment to religion and ornamentation. However, the details on their domestication process are still controversial, especially the origin and evolution of African chickens. Egypt is thought to be important place for this event because of its geographic location as well as its long history of civilization. However, the genetic component and structure of Egyptian native chicken (ENC) have not been studied so far. The aim of this study is to clarify the origin and evolution of African chickens through assessing the genetic diversities and structure of five ENC breeds using the mitochondrial D-loop sequences. Our results suggest there is genetic differentiation between the pure native breeds and the improved native breeds. The latter breeds were established by the hybridization of the pure native and the exotic breeds. The pure native breeds were estimated to be established about 800 years ago. Subsequently, we extensively analyzed the D-loop sequences from the ENC as well as the globally collected chickens (2,010 individuals in total). Our phylogenetic tree among the regional populations shows African chickens can be separated to two distinct clades. The first clade consists of North African (Egypt), Central African (Sudan and Cameroon), European, and West (and Central) Asian chickens. The second clade consists of East African (Kenya, Malawi, and Zimbabwe) and Pacific chickens. It suggests the dual origins of African native chickens. The first group was probably originated from South Asia, and then migrated to West Asia, and finally arrived to Africa thorough Egypt. The second group migrated from Pacific to East Africa via Indian Ocean probably by Austronesian people. This dual origin hypothesis as well as estimated divergence times in this study is harmonious with the archaeological and historical evidences. Our migration analysis suggests there is limited gene flow within African continent. These obtained findings are important for the better understanding of the diversity and uniqueness of African native chickens. [ABSTRACT FROM AUTHOR]

Chicken Mx protein confers resistance against viral infections including avian influenza virus. Mx protein is one of the strong antiviral proteins induced by interferon system. Different alleles of chicken Mx gene have been shown to vary in their antiviral activity against influenza virus. A non-synonymous mutation at position 2032 of chicken Mx gene responsible for variation of amino acid (Ser to Asn) in Mx protein is responsible for negative to positive antiviral activity of Mx protein. In the present study it was analyzed that SNP at G2032A in chicken Mx gene in two Indian native chicken breeds, Aseel, Kadaknath and compared with White Leghorn layer. A total of 90 samples, including 50 of White Leghorn and 20 each from native chicken breed were screened for SNP at position 2032 of Mx gene by using real time multiplex allele specific PCR. The resistant allele (A) frequency is higher than susceptible allele in all three chicken breeds investigated. Among the breeds, the resistant allele frequency (A) is higher in White Leghorn (0.95) followed by Aseel (0.75) and Kadaknath (0.625). Homozygous to resistant allele (AA) is the major genotype in White Leghorn whereas heterozygous to both alleles is the major genotype in Kadaknath. Variations in the gene frequency might have emerged from varying degree of selection pressure the different breeds had undergone. In future, the resistant genotype could be selected in modern breeding programs to improve the genetic status for disease resistance against viral infections. [ABSTRACT FROM AUTHOR]

The research aims to define the breeding objective traits of Boholano strain of native chicken using participatory approach to be incorporated for its purification. A total of 45 households were interviewed. The questionnaire was designed to collect data covering general information on village poultry production such as socio-management characteristics, production objectives, population structure, breed choice and trait preferences, market preferences of specific traits, and farmers' selection practices. The participatory farmers' discussions were designed to involve stakeholders in defining the breeding objective traits and deriving their relative importance in the production environment based on the different functions of chickens and traits identified in the interviews. The results showed that production of eggs for consumption is the principal function of chickens in most towns followed by the use as source of income and meat for home consumption. Weight is the primary factor that dictates market price but farmers rated growth and number of eggs as the production traits that they would like to be improved. Therefore, the breeding objective should be to develop dual-purpose Boholano strain of native chicken considering the traits of number of eggs and live weight and possessing the distinct plumage color and comb type. [ABSTRACT FROM AUTHOR]

The genetic diversity of four protected indigenous chicken breeds was evaluated with 25 microsatellite markers. Polymorphism information content (PIC), heterozygosity with the estimator of genetic differentiation FST and Nei's genetic distance were evaluated. The results showed that these four protected local chicken populations showed high levels of diversity. The proportion of inter-population subdivision among the four protected local chicken populations was 16.0%. The average heterozygosity was 0.514, 0.581, 0.567 and 0.589 in Dongan, Xuefeng black-bone, Xianghuang and Taoyuan chickens, respectively, while the average PIC estimates were 0.455, 0.581, 0.557 and 0.576. A phylogenetic tree was constructed using genetic distance and the neighbour-joining method. Its topology reflects the general pattern of genetic differentiation among the four chicken breeds. The results also showed high genetic diversity and genetic variation among all the breeds. The information about the four local breeds estimated by microsatellite analysis may be useful as an initial guide for the effective conservation of chicken genetic diversity and developing conservation strategies. [ABSTRACT FROM AUTHOR]

This study was carried out to figure the potentiality of d-loop of mitochondrial DNA in discriminating among Saudi native chicken strains and other species of genus Gallus. The first 500 base pairs of d-loop region were amplified and successfully sequenced. The results indicated that native chicken strains and genus Gallus species have a tandem repeat sequence with (14) base units into a two copy. Also, there was clear evidence that the native chickens have a unique tandem repeat sequence with (42) base units as a two copy. Two haplotypes (T) and (C) were observed in native chicken strains. Our research displayed approximately (26) transition substitutions in nucleotide sequences specific for native chicken strains, whereas it was 120 mutant sites in case of other species of Gallus. We found that the genetic divergence between these types of chickens was very low (0.022). The phylogenetic tree revealed that each strain of native chicken belonged to each other with the same cluster. In addition, each strain has its own cluster in some individuals. The results showed that the native chicken strains are closely related to Gallus gallus and its subspecies G. g. spadiceus and G/. g. bankiva. [ABSTRACT FROM AUTHOR]

The complete mitochondrial D-loop region was sequenced for a total of 18 individuals of Bangladeshi native chickens (BNC); full feathered (nana) (n = 7), naked neck (Nana) (n = 8) and Red junglefowl (RJF) (n = 3). The alignment of mitochondrial D-loop sequence of these chicken populations with 39 reference sequences from DNA databank; White Leghorn, G. g. murghi, G. g. bankiva, G. g. spadiceus, G. g. gallus and other Asiatic chickens was done to identify the phylogenetic position of BNC for the conservation and improvement of chicken genetic resource. The nucleotide variation of sequence among haplotypes for within and between populations of BNC supported the phenotypic variation of individual of the populations. Phylogenetic analysis showed that 57 individuals were grouped into 6 clades. Of the BNC populations, 6 nana, 7 Nana and 2 RJF individuals (83.3%) were closely related with each other and only 1 nana and 1 Nana (11%), and 1 RJF (5.5%) individuals were divergent from them. Therefore, the phylogenetic tree showed low genetic distance and close relationship within and between the chicken populations of Bangladesh, which were closely related with G. g. murghi of Indian origin, and also related with G. g. bankiva, G. g. gallus implying the origin of gene flow to Bangladesh. The genetic information from this study may serve as an initial step to make future plans to assess more molecular information on genetic diversity for the characterization, conservation and improvement of valuable chicken genetic resource of Bangladesh. [ABSTRACT FROM AUTHOR]

Abstract: Comparative resistance to different isolates of Ascaridia galli was investigated in a local chicken breed from Jordan (LC) and in the Lohmann LSL white chicken (LW) strain. In two trials, birds of LC and LW were inoculated orally at 1-day old with 250 embryonated A. galli eggs. In the first trial a German source of A. galli was used, whereas in the second trial, a Jordan source of A. galli was used. At week 7 of infection, infected LC birds harbored significantly (P <0.05) fewer worms and excreted less A. galli eggs than infected LW birds. A. galli isolated from Jordan were less infectious than A. galli from Germany. Results suggest that the variation in genetic background between LC and LW is involved in the resistance to A. galli infection. A. galli isolates from different geographic areas differ in their ability to infect different chicken genotypes. [Copyright &y& Elsevier]

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This study was conducted to understand the influence of the chicken footpad dermatitis (FPD) on the litter contained 0%, 10% and 20% of biochar. Crossbred chickens were reared in this experiment. The extra water was added into the litter for inducing the FPD symptom. The results showed that the average litter' moisture content, seemed inversely proportional to the biochar added, in the three groups were 53.8, 51.8 and 50.3%, respectively. Finally, the incidence of FPD in the three groups at the end of the trial was 49.5, 71.4, and 70.2%, respectively. The highest FPD score was 0.83 in the 10% biochar group and 0.53 in the 0% biochar group. The birds with 2 points FPD score is 3.8% in the 0% biochar group. In general, although the moisture content in the litter is reduced by added certain proportion of biochar, the effect of improving the incidence and dermatitis on the foot of the chicken is not as effective as expected. [ABSTRACT FROM AUTHOR]