RNA-Seq analysis reveals expression regulatory divergence of W-linked genes between two contrasting chicken breeds

The regulation of gene expression is a complex process involving organism function and phenotypic diversity, and is caused by cis- and trans- regulation. While prior studies identified the regulatory pattern of the autosome rewiring in hybrids, the role of gene regulation in W sex chromosomes is not clear due to their degradation and sex-limit expression. Here, we developed reciprocal crosses of two chicken breeds, White Leghorn and Cornish Game, which exhibited broad differences of gender-related traits, and assessed the expression of the genes on W chromosome to disentangle the contribution of cis- and trans-factors to expression divergence. We found that there was not appear to be an association between female fecundity and W chromosome gene expression, that 44% of expressed genes had divergent expression between breeds in both tissues, with only 17% of them showing greater expression in White Leghorn. We observed that the proportion of trans-acting genes in W chromosome was higher than cis-regulatory divergence. There were most parental divergence expression genes in muscle, also more heterosis compared with other two tissues. A strong dominant impact of Cornish alleles in brain, while obvious crosses-specific regulatory patterns appeared in liver. Taken together, this work describes the regulatory divergence of W-linked genes between two contrasting breeds and indicates sex chromosomes have a unique regulation and expression mechanism.

Determinants of Rural Households’ Poultry Chicken Breeds Choice in Wolaita, Ethiopia

To achieve increased productivity in poultry chicken, households’ choice of poultry chicken breeds should be maintained according to their desirability. This study aimed at identifying determinants of rural households’ choice of poultry chicken breeds keeping in Wolaita, Ethiopia. Multistage sampling techniques were used. First, Damot Pulasa district was selected purposively because of high poultry production potential, and then simple random sampling technique was used to select five kebeles and at third stage systematic random sampling was used to select 160 rural households. Data were collected through interview schedule and analyzed using descriptive statistics and econometric regression. Result showed that 54.37% of households owned indigenous poultry chicken breed, 38% owned exotic poultry chicken breeds and 7.63% owned both indigenous and exotic poultry chicken breeds. Households attached socioeconomic, demographic and institutional factors and breed related traits to their poultry chicken breed choices. Indigenous chicken breeds were preferred in mothering ability, disease resistance, scavenging ability; taste of meat and egg traits whereas exotic poultry chicken breeds were preferred for growth rate, productivity and total eggs laid per chicken per year. In addition, Multinomial Logit model result indicated that age and education level of household head determined poultry chicken breed choice. To be effective and efficient any poultry chicken breed promotion effort in the future should consider these particular preferences of households.

China as a Center of Origin and Domestication of Chicken: A Review

China has about 107 local chicken breeds and is considered one of the richest countries in terms of genetic resources. This diversity is a source of richness natural resources across the globe and is regarded as an excellent material for genetic improvement of breeds or breeding new breeds around the world. The present review highlights the recent evidence and studies of chicken origin and domestication in China and Southeast Asia. The evidence of molecular genetics and archeological results supported that multiple regions and event were contributed to the creation of chicken evolution from Red Jungle fowl and the findings proposed that one of events happened in domestication of chicken 8000 BP in Southeast of Asia. Several researchers confirmed that China was declared as most important of the world as a first centers for the chicken’s domestication and these chickens have remained in many archaeological sites in China.

Comparative Growth Performance of Kuroiler and Nigerian Indigenous Naked Neck Chickens Kept in a Tropical Environment

Chicken production is an essential venture for steady household income generation, poverty alleviation and provision of quality nutritional aids. This study was conducted to compare growth performance of Kuroiler and Nigerian indigenous naked neck chickens reared in the tropics. A total of 538 birds comprising 345 indigenous Nigerian naked neck and 193 Kuroiler chickens genotypes were sampled. Body weight and linear body measurements were observed at 2, 4, 6, 8 and 10th week. Data obtained were subjected to 2-way analysis of variance using GLM procedure of SAS. There exist significant variations in chicken genotype with growth performance. Kuroiler birds significantly showed heavier mean body weight (p<0.05) at various critical growth stages observed than the Nigerian indigenous naked neck chickens reared under same conditions. The influence of genotype and sex on mean body weight and breast girth measures of chickens remain insignificant throughout early growth stages. However, at 6th, 8th and 10th week of age, Kuroiler breeds demonstrated superior growth rate and performance response compared to Nigerian indigenous naked neck fowls. Both chicken breeds exhibited differential growth patterns and sexual dimorphism in favour of male populations. Introduction and crossing of Kuroiler strains with Nigerian indigenous naked neck birds might result in better performance and adaptability.

Genetic Effect and Growth Curve Parameter Estimation under Heat Stress in Slow-Growing Thai Native Chickens

Heat stress is becoming a major problem because it limits growth in poultry production, especially in tropical areas. The development of genetic lines of Thai native chickens (TNC) which can tolerate the tropical climate with the least compromise on growth performance is therefore necessary. This research aims to analyze the appropriate growth curve function and to estimate the effect of heat stress on the genetic absolute growth rate (AGR) in TNC and Thai synthetic chickens (TSC). The data comprised 35,355 records for body weight from hatching to slaughtering weight of 7241 TNC and 10,220 records of 2022 TSC. The best-fitting growth curve was investigated from three nonlinear regression models (von Bertalanffy, Gompertz, and logistic) and used to analyze the individual AGR. In addition, a repeatability test-day model on the temperature-humidity index (THI) function was used to estimate the genetic parameters for heat stress. The Gompertz function produced the lowest mean squared error (MSE) and Akaike information criterion (AIC) and highest the pseudo-coefficient of determination (Pseudo-R2) in both chicken breeds. The growth rates in TSC were higher than TNC; the growth rates of males were greater than females, but the age at inflection point in females was lower than in males in both chicken breeds. The THI threshold started at 76. The heritability of the AGR was 0.23 and 0.18 in TNC and TSC, respectively. The additive variance and permanent environmental variance of the heat stress effect increased sharply after the THI of 76. The growth rate decreased more severely in TSC than TNC. In conclusion, the Gompertz function can be applied with the THI to evaluate genetic performance for heat tolerance and increase growth performance in slow-growing chicken.

Association of insulin-like growth factor 1 (IGF1) gene polymorphism with the reproductive performance of three dual-purpose chicken breeds

The study was designed to investigate the association of Insulin-like growth factor 1 (IGF1) gene polymorphism with the reproductive performance of FUNAAB-Alpha, Sasso, and Kuroiler dual-purpose chicken breeds. To achieve this, a total of 250 healthy hens were selected at 12 weeks of age and were intensively managed in cages for 52 weeks. Blood sample was taken from each chicken at the 34th week and genomic DNA was extracted using Qiagentm DNA extraction kit, PCR was used to amplify the DNA fragments, and the PCR products were electrophoresed. Amplicons obtained were digested with restriction enzyme hinf1, and were further electrophoresed on 1.5% agarose gel. Data obtained were analyzed using the General linear model of SAS (2002) version 9.0 to determine the effect of IGF1 gene polymorphism and the distribution of alleles within the breeds. Results show polymorphism of the IGF1 gene and the restriction analysis indicated two alleles; A 58% and C 42% with the identification of genotypes AA, AC, and CC, and genotypic frequency of 22%, 43% and 35% respectively. Significant associations were observed between the polymorphism of the IGF1 gene, age of the bird at first lay, and weight of the hen at first lay. Chickens with haplotype CC came earlier into lay compared to those with the other two haplotypes (AA and AC). Therefore, the study suggests that haplotype CC could be used as a genetic marker to select for an improved laying performance in chickens.

Tear Production, Intraocular Pressure, Ultrasound Biometric Features and Conjunctival Flora Identification in Clinically Normal Eyes of Two Italian Breeds of Chicken (Gallus gallus domesticus)

Given the abundance of chickens in Italy, it is important for veterinarians to know the normal state of chickens’ eyes in order to identify any ophthalmic pathological changes. The aim of this study was to determine the normal values of select ocular parameters and to evaluate conjunctival microflora in two Italian chicken breeds. Sixty-six healthy chickens underwent a complete ophthalmic examination, which included a phenol red thread test (PRTT) for the evaluation of tear production and the assessment of intraocular pressure by rebound tonometry. B-mode ultrasound biometric measurements and conjunctival microflora identification were also performed in twenty-seven chickens. Mean PRTT was 23.77 ± 2.99 mm/15 s in the Livorno breed and 19.95 ± 2.81 mm/15 s in the Siciliana breed. Mean intraocular pressure was 14.3 ± 1.17 mmHg in the Livorno breed and 14.06 ± 1.15 mmHg in the Siciliana breed. Reference ranges for morphometric parameters were reported in the two breeds. Twenty-three chickens (85.18%) were bacteriologically positive. Chlamydia spp. antigen was detected in 14.81% of chickens. No positive cultures were obtained for fungi. Normal reference range values for selected ophthalmic parameters were obtained in clinically healthy chickens, which could facilitate accurate diagnosis and better management of ophthalmic diseases in these animals.

Integrative Analysis of Transcriptomics and Metabolomics to Reveal the Melanogenesis Pathway of Muscle and Related Meat Characters in Wuliangshan Black-Boned Chickens

Background: Melanin is an important antioxidant in food, and has been used in medicine and cosmetology. Chicken meat with high melanin content from black-boned chickens have been considered a high nutritious food with potential medicinal properties. The molecular mechanism of melanogenesis of skeletal muscle in black-boned chickens remain poorly understood. This study investigated the biological gene-metabolite associations regulating the muscle melanogenesis pathways in Wuliangshan black-boned chickens with two normal boned chicken breeds as control.Results: We identified 25 differentially expressed genes and 11 transcription factors in the melanogenesis pathways. High levels of the meat flavor compounds inosine monophosphate, hypoxanthine, lysophospholipid, hydroxyoctadecadienoic acid, and nicotinamide mononucleotide were found in Wuliangshan black-boned chickens.Conclusion: Integrative analysis of transcriptomics and metabolomics revealed the dual physiological functions of the PDZK1 gene, involved in pigmentation and/or melanogenesis and regulating the phospholipid signaling processes in muscle of black boned chickens.