Jiangxian Wang

The avian respiratory system, characterized by its caudocranial unidirectional pulmonary airflow, has long fascinated scientists. To date, the mechanisms underlying the unidirectional airflow and the formation of aerodynamic valving, especially the expiratory valve, remain poorly understood. To provide new insights into pulmonary airflow characteristics and to deepen our understanding of the role of aerodynamic valving in generating unidirectional pulmonary airflow, the respiratory tract of a domestic chicken was reconstructed based on CT-scanned data. CFD simulations were performed under various conditions after validation of the numerical model. Flow parameters were analyzed qualitatively and quantitatively during inspiration and expiration phases, respectively. The results showed that the coupled interaction of the distinctive bronchial topology and air-sac pressure conditions preferentially routed inspired air toward the caudal-sac pathways during inspiration. During expiration, aerodynamic valving was primarily associated with a momentum barrier generated by the cranial-sac airstream, which suppressed retrograde caudal-sac airflow through the primary bronchus and redirected it toward the dorsobronchial outlets leading to the physiological paleopulmonic pathway. Moreover, the ‘segmentum accelerans’ structure facilitated the formation of aerodynamic valving, whereas its removal did not abolish major-bronchial flow rectification, although higher air-sac boundary pressures were required during expiration. Finally, fluid density substantially affected inspiratory aerodynamic valving, whereas its effect on the critical pressures associated with expiratory valving remained below 5%.

Skeletal muscle growth and development represent a pivotal biological process that determines both the yield and quality of poultry meat. As chickens age, there is an observable shift in their muscle structure, function and metabolic properties. However, the molecular mechanisms by which age regulates chicken muscle development and meat quality formation are not yet fully understood. The objective of this study was to elucidate the fundamental molecular mechanisms through which the aging process influences the development of chicken muscle and the quality of meat. A total of 20 female Dahen chickens, comprising 10 birds at 3 months of age and 10 at 72 months of age, were subjected to systematic measurements of meat quality indexes and muscle fiber characteristics. From each age group, 3 out of the 10 birds were randomly selected for breast muscle transcriptome analysis. The results demonstrated that aged chicken breast muscle exhibited reduced tenderness, augmented intramuscular fat content and water-holding capacity, while muscle fibers demonstrated significant hypertrophy and reduced density. A total of 819 differentially expressed genes (DEGs) were identified by RNA-seq, which were predominantly enriched in the biological processes of muscle system process, muscle organ development, and skeletal muscle cell differentiation, and were involved in the pathways of cytoskeleton in muscle cells, and extracellular matrix (ECM)–receptor interaction signaling, among others. The expression of key genes, such as COL1A2, THBS2, FN1, and MYBPC1, was found to be significantly altered, a finding that was verified by qPCR in agreement with the sequencing results. The study demonstrated that age impacts meat quality traits by inducing muscle fiber hypertrophy, ECM remodeling and metabolic reprogramming. The related genes provide a valuable reference point for understanding the genetic regulation of avian muscle development and meat quality.

The evolution of the chilled processing technology has precipitated the emergence of ice-fresh poultry meat as a significant sales channel. The aesthetic appearance of chicken carcasses has become increasingly important in the context of poultry ice-fresh sales, in conjunction with the comprehensive implementation of China’s policies for poultry. Feather follicle development is a significant factor in determining the aesthetic appearance of the carcass. Recent studies have focused on the molecular mechanisms associated with feather follicle development. The WNT, EGF, FGF, SHH, and BMP signalling pathways have been identified as the regulatory mechanisms involved in the development of feather follicles in various segments of poultry skin. However, the BMP signalling pathway, acting as an inhibitor, has been demonstrated to impede the regulatory processes governing feather follicle development via these signalling pathways. This review summarises the structure and overview of feathers and feather follicles, the research progress of signalling pathways that affect the development of poultry feather follicles, the research progress of poultry follicle traits, and the research progress of feather follicle development biotechnology. The present review focuses on summarising the molecular mechanisms that affect feather follicle development, and on providing a summary of the application of biotechnology in this field. It also offers ideas and theoretical references for the molecular mechanism of poultry feather follicle development.

In this study, we combined genomic and gut microbiome data to evaluate 13 economically important growth and feed efficiency traits in 407 Dahen broilers, including body weight (BW) at four, six, nine, and ten weeks of age (BW4, BW6, BW9, and BW10), as well as the average daily gain (ADG6, ADG9, and ADG10), feed conversion ratio (FCR6, FCR9, and FCR10), and residual feed intake (RFI6, RFI9, and RFI10) for the three growing ages. The highest ADG and lowest FCR were observed at nine and six weeks of age, respectively. We obtained 47,872 high-quality genomic single-nucleotide polymorphisms (SNPs) by sequencing the genomes and 702 amplicon sequence variants (ASVs) of the gut microbiome by sequencing the 16S rRNA gene, both of which were used for analyses of linear mixed models. The heritability estimates (± standard error, SE) ranged from 0.103 ± 0.072 to 0.156 ± 0.079 for BW, 0.154 ± 0.074 to 0.276 ± 0.079 for the ADG, 0.311 ± 0.076 to 0.454 ± 0.076 for the FCR, and 0.413 ± 0.077 to 0.609 ± 0.076 for the RFI traits. We consistently observed moderate and low negative genetic correlations between the BW traits and the FCR and RFI traits (r = −0.562 to −0.038), whereas strong positive correlations were observed between the FCR and RFI traits (r = 0.564 to 0.979). For the FCR and RFI traits, strong positive correlations were found between the measures at the three ages. In contrast to the genomic contribution, we did not detect a gut microbial contribution to all of these traits, as the estimated microbiabilities did not confidently deviate from zero. We systematically evaluated the contributions of host genetics and gut microbes to several growth and feed efficiency traits in Dahen broilers, and the results show that only the host genetics had significant effects on the phenotypic variations in a flock. The parameters obtained in this study, based on the combined use of genomic and gut microbiota data, may facilitate the implementation of efficient breeding schemes in Dahen broilers.