Li Yang

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.

Airborne diseases pose a significant challenge in intensive livestock farming due to their rapid transmission. Aerosols facilitate the spread of pathogens, introducing external infections to farms and enabling cross-transmission within barns. To address knowledge gaps in aerosol dynamics in animal respiratory tracts and enhance understanding of airborne disease transmission, this study employed CT scanning, 3D printing, and CFD technologies to develop and validate a pig respiratory model. Qualitative and quantitative results from the present study reveal spatiotemporal heterogeneity in aerosol deposition and transmission. Under rest conditions, for aerosols with D ≤ 5.0 μm, 21.1% of inhaled aerosols were deposited in the lung by the end of a respiratory cycle. Doubling the respiratory cycle or the inhalation rate could further increase the penetration ability of small-sized aerosols by approximately 60% to 70%. Moreover, the asymmetric distribution of airflow between the left and right halves of the lower respiratory tract (Q_L/R = 0.89) resulted from the leftward position of the pig’s heart and consequently led to a deposition ratio of about 0.83 between the left and right bronchial airways. These findings provide fundamental scientific data for the development and application of aerosolized vaccines and offer insights into optimizing respiratory intervention strategies.

Ferritin heavy chain 1 (FTH1) is pivotal in the storage, release, and utilization of iron, plays a crucial role in the ferroptosis pathway, and exerts significant impacts on various diseases. Iron influences skeletal muscle development and health by promoting cell growth, ensuring energy metabolism and ATP synthesis, maintaining oxygen supply, and facilitating protein synthesis. However, the precise molecular mechanisms underlying iron’s regulation of skeletal muscle growth and development remain elusive. In this study, we demonstrated that the conditional knockout (cKO) of FTH1 in skeletal muscle results in muscle atrophy and impaired exercise endurance. In vitro studies using FTH1 cKO myoblasts revealed notable decreases in GSH concentrations, elevated levels of lipid peroxidation, and the substantial accumulation of Fe²⁺, collectively implying the induction of ferroptosis. Mechanistically, E3 ubiquitin-protein ligase SMURF1 (SMURF1) acts as an E3 ubiquitin ligase for FTH1, thereby facilitating the ubiquitination and subsequent degradation of FTH1. Consequently, this activation of the ferroptosis pathway by SMURF1 impedes myoblast differentiation into myotubes. This study identifies FTH1 as a novel regulator of muscle cell differentiation and skeletal muscle development, implicating its potential significance in maintaining skeletal muscle health through the regulation of iron homeostasis.

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.

Indoor environmental control is usually applied in poultry farming to ensure optimum growth conditions for birds. However, these control methods represent a considerable share of total energy consumption, and the trend of applying new equipment in the future for precision livestock farming would further increase energy demand, resulting in an increase in greenhouse gas emissions and management costs. Therefore, to ensure optimum efficiency of both energy use and livestock productivity, a customized hourly model was developed in the present study to interpret and analyze the electronically collected data. The modules for estimating indoor gas concentrations were incorporated into the present model, as this has not been properly considered in previous studies. A validation test was performed in a manure-belt layer house using sensors and meters to measure the indoor environmental parameters and energy consumption. The predicted results, including indoor temperature, relative humidity, carbon dioxide and ammonia concentrations, showed good agreement with the measured data, indicating a similar overall trend with acceptable discrepancies. Moreover, the corresponding differences between the measured and simulated energy consumption for heating, tunnel ventilation and base ventilation were 13.7, 7.5, and 0.1%, respectively. The total energy demand estimated by the model showed a limited discrepancy of approximately 10.6% compared with that measured in reality. Although human factors, including inspection, cleaning, vaccination, etc., were not included in the model, the validation results still suggested that the customized model was able to accurately predict the indoor environment and overall energy consumption during poultry farming. The validated model provides a tool for poultry producers to optimize production planning and management strategies, increase the production rate of unit energy consumption and achieve precision livestock farming from an energy consumption standpoint.

The main advantage of having livestock, for example, the laying hens, in a controlled environment is that the optimum growth conditions can be achieved with accuracy. The indoor air temperature, humidity, gases concentration, etc., would significantly affect the animal performance, thus should be maintained within an acceptable range. In order to achieve the goals of precision poultry farming, various models have been developed by researchers all over the world to estimate the hourly indoor environmental parameters so as to provide decision suggestions. However, a key parameter of hourly manure area in the poultry house was missing in the literature to predict the ammonia emission using the recently developed mechanistic model. Therefore, in order to fill the gap of the understanding of hourly manure coverage proportion and area on the manure belt, experimental measurements were performed in the present study using laying hens from 10 weeks age to 30 weeks age. For each test, six polypropylene (pp) plates were applied to collect the manure dropped by the birds every hour, and photographs of the plates were taken at the same time using a pre-fixed camera. Binary images were then produced based on the color pictures to determine the object coverage proportion. It was demonstrated that for laying hens of stocking density around 14 birds/m², the manure coverage proportion at the 24th hour after the most recent manure removal was about 60%, while the value was approximately 82% at the 48th hour. Meanwhile, for laying hens at different ages, the hourly increment of manure coverage proportion showed a similar pattern with four distinct stages within 48 h. The statistical analyses demonstrated no significant correlation between the hourly increment of manure weight and the hourly increment of manure coverage proportion. Finally, prediction models for estimating the hourly manure coverage proportion on the manure belt in typical laying hen houses were provided.