Commercial Chickens Research Articles

Breeding practice of indigenous village chickens, and traits and breed preferences of smallholder farmers.

Indigenous village chickens, or (IVCs), significantly contribute to rural livelihoods. Although natural selection has a disproportionate impact on the genetic structure of IVCs, farmers have developed locally tailored breeding practices to get the most out of their flocks. Small-scale farmers' insights on trait breed preferences and family flock breeding practices are presented in this cross-sectional study. A cross-sectional study was conducted in two agroecological zones using face-to-face individual interviews with 119 general informants. Farmers prefer IVCs because they are multipurpose birds. Unlike policymakers, who usually underestimate the importance of IVCs, small-scale farmers acknowledge the coexistence of local and commercial chickens. Only 15.7% of farmers recruited homegrown cocks, whereas 47.9% outsourced breeding cocks from local markets and 36.4% from neighbours (χ-squared=15.976, df=2, p=0.0003395). About 49.2% of small-scale farmers believed that consanguineous mating-induced inbreeding has only trivial effects. High flock turnover significantly reduces inbreeding. Regardless of the low production capacity, small-scale farmers prefer local (rank=1.47) chickens to commercial (rank=1.61). For cocks, fertility and growth traits were highly sought after, whereas for hens, maternal instincts and laying performance were prioritized. Compared to the highlands, the lowlands had a longer egg storage period (t=2.677, df=117, p=0.009, 95% CI: -3.7607, -0.5622). This study documented the wisdom of small-scale farmers and encouraged the incorporation of their insights into a sustainable genetic improvement program.

The IncC and IncX1 resistance plasmids present in multi-drug resistant Escherichia coli strains isolated from poultry manure in Poland

The study describes the whole-genome sequencing of two antibiotic-resistant representative Escherichia coli strains, isolated from poultry manure in 2020. The samples were obtained from a commercial chicken meat production facility in Poland. The antibiotic resistance profile was characterized by co-resistance to β-lactam antibiotics, aminoglycosides, and fluoroquinolones. The three identified resistance plasmids (R-plasmids), pECmdr13.2, pECmdr13.3, and pECmdr14.1, harbored various genes conferring resistance to tetracyclines (tetR[A]) for, aminoglycoside (aph, aac, and aad families), β-lactam (blaCMY-2, blaTEM-176), sulfonamide (sul1, sul2), fluoroquinolone (qnrS1), and phenicol (floR). These plasmids, which have not been previously reported in Poland, were found to carry IS26 insertion elements, the intI1-integrase gene, and conjugal transfer genes, facilitating horizontal gene transfer. Plasmids pECmdr13.2 and pECmdr14.1 also possessed a mercury resistance gene operon related to transposon Tn6196; this promotes plasmid persistence even without antibiotic selection pressure due to co-selection mechanisms such as co-resistance. The chicken manure–derived plasmids belonged to the IncX1 (narrow host range) and IncC (broad host range) incompatibility groups. Similar plasmids have been identified in various environments, clinical isolates, and farm animals, including cattle, swine, and poultry. This study holds significant importance for the One Health approach, as it highlights the potential for antibiotic-resistant bacteria from livestock and food sources, particularly E. coli, to transfer through the food chain to humans and vice versa.

Desempenho econômico e zootécnico de frangos de corte submetidos à restrição alimentar quantitativa

Nutrition today accounts for approximately 75% of broiler production costs due to the large variety of ingredients contained in poultry feed. Commercial chicken breeds have been genetically selected for rapid weight gain, among other characteristics, thereby stimulating their voracious feeding behavior. However, this greater feed intake has not seen an attendant increase in the digestion capacity of the birds’ digestive system, thus interfering with feed conversion. The objective of this study to compare the performance of feed conversion, mortality rates, daily weight gain, carcass rejections, carcass and parts yields and the cost of ad libitum feeding of broiler chickens with those achieved through quantitative feed restriction (Cobb broiler diet table and 10% less than recommended in the table). The treatments were tested in three consecutive batches on a poultry farm with three aviaries. The results obtained indicated that quantitative feed restriction improves feed conversion and reduces daily weight gain and mortality rates, but affects neither carcass rejection rates nor carcass and parts yields. As for production costs, the kilogram of live chicken was 5.69% lower among birds that received controlled feed, following the diet recommended for the breed, and 7.38% in birds that received a 10% quantitative feed restriction compared to the Cobb broiler diet table. The results of this study indicate that the use of quantitative feed restriction programs, despite the lower daily weight gain of broiler chickens, can offer advantages because lower mortality rates and enhanced feed conversion compensate for this loss, thus significantly reducing production costs.

An efficient transformer network for detecting multi-scale chicken in complex free-range farming environments via improved RT-DETR

Accurate detection and localization of chicken targets in complex environments are the foundation of intelligent free-range chicken farming. However, commercial free-range chicken farming poses several challenges to detection methods, including complex and variable backgrounds, multi-scale targets, aggregated occlusion and changes in the posture of chicken. While there has been significant research on object detection algorithms based on convolutional neural networks, these algorithms have limited effectiveness in detecting small targets and generalizing to new scenes. Therefore, this study proposes a highly accurate and strongly generalizable chicken object detection model called Efficient Multi-scale Chicken DETR (EMSC-DETR), which is based on an improved Real-Time DEtection TRansformer (RT-DETR). To address the issue of easily losing small target features, a new efficient transformer module called space-to-depth transformer module (SDTM) is introduced. SDTM includes space-to-depth (SPD) and BiFormer modules, which facilitate deep interaction between local and global features, and significantly improve the computational efficiency of the transformer. Additionally, to overcome the detection and differentiation difficulties caused by chicken aggregation occlusion, the transformer encoder of EMSC-DETR incorporates a contextual transformer (CoT). CoT utilizes rich contextual information among the nearest neighbors to enhance the feature representation of high-level features, enabling more accurate localization of overlapped chicken targets. To evaluate the proposed model in complex environments, 14 scene data were collected from two fields and divided into training, validation, testing sets and three independent testing sets with unknown scenes. Experimental results show that the proposed EMSC-DETR obtains the best detection performance in the testing set, with an AP50 of 98.6%, surpassing other state-of-the-art models of similar size. In the three independent testing sets, the proposed model shows improvements of 8.2%, 9.2% and 28.3% in the AP50 compared to the original RT-DETR, respectively. Moreover, the model exhibits superior generalization ability for unknown scenes compared to other state-of-the-art models. Robustness and fine-tuning experiments further confirm the reliability and application potential of EMSC-DETR in detecting free-range chickens, which is crucial for complex commercial farming. This study is expected to provide references and new ideas for precision livestock farming.

Designing and development of efficient multi-epitope-based peptide vaccine candidate against emerging avian rotavirus strains: A vaccinomic approach

BackgroundEnteric avian rotavirus (ARV) is the etiological agent of several health problems that pose a global threat to commercial chickens. Therefore, to avoid these widespread epidemics and high mortality rates, only vaccine and strict biosecurity are required. MethodThe present study employs computational techniques to design a unique multi-epitope-based vaccine candidate that successfully activates immune cells against the ARV by combining adjuvant, linker, and B and T-cell epitopes. Starting, homologous sequences in the various ARV serotypes were revealed in the NCBI BLAST database, and then the two surface proteins (VP4 and VP7) of the ARV were retrieved from the UniprotKB database. The Clustal Omega server was then used to identify the conserved regions among the homologous sequences, and the B and T-cell epitopes were predicted using IEDB servers. Then, superior epitopes—2 MHC-1 epitopes, 2 MHC-2 epitopes, and 3B-cell epitopes—were combined with various adjuvants to create a total of four unique vaccine candidates. Afterward, the designed vaccine candidates underwent computational validation to assess their antigenicity, allergenicity, and stability. The vaccine candidate (V2) that demonstrated non-antigenicity, a high VaxiJen score, and non-allergenicity was ultimately chosen for molecular docking and dynamic simulation. ResultsAlthough the V2 and V4 vaccine candidates were highly immunogenic, V2 had a higher solubility rate. The predicted values of the aliphatic index and GRAVY value were 30.4 and 0.417, respectively. In terms of binding energy, V2 outperformed V4. Being successfully docked with TLRs, V2 was praised as the finest. After adaptation, the sequence’s 50.73 % GC content outside of the BglII or ApaI restriction sites indicated that it was equivalently safe to clone. The chosen sequence was then inserted into the pET28a(+) vector within the BglII and ApaI restriction sites. This resulted in a final clone that was 4914 base pairs long, with the inserted sequence accounting for 478 bp and the vector accounting for the remainder. ConclusionsThe immune-mediated simulation results for the selected vaccine construct showed significant response; thus, the study confirmed that the selected V2 vaccine candidate could enhance the immune response against ARV.

Autonomous navigation using machine vision and self-designed fiducial marker in a commercial chicken farming house

Indoor navigation within commercial animal farming houses is crucial for the increasing operations carried out by mobile robots. However, existing methods often suffer from issues such as sensitivity to ambient light, insufficient accuracy for precise animal operations, or complexity in implementation. In this study, we proposed a novel navigation method for mobile chassis in a commercial stacked cage farming house, utilizing an active light source, self-designed fiducial marker, and machine vision. Our navigation system incorporated imaging modules equipped with 850 nm infrared light to minimize animal stress and mitigate the effects of low illumination. The self-designed fiducial marker, DRITag, enabled precise maker identification with a recognition rate of 100 % and achieved high positioning accuracy, with an absolute mean error of 0.34 cm within a range of 1.2 m. To determine the chassis’ yaw angle, we employed the U-net deep learning network, which achieved satisfactory root mean square errors of 0.22° and 0.10° on the ground and upper floors, respectively. Global localization of the chassis across different farm areas was achieved through a combination of DRITag and odometry information. Our proposed method provided a flexible and user-friendly approach to navigation path planning, employing a waypoint task text file that enabled easy modification of the path through simple text file editing. Field tests conducted in a two-story commercial stacked cage chicken farming house demonstrated the high accuracy of our navigation method, with standard deviations of longitudinal deviations below 1.85 cm and 1.82 cm, and standard deviations of lateral deviations below 1.50 cm and 1.12 cm at a speed of below 0.3 m/s on the ground floor and at a speed of 0.2 m/s on the upper floor, respectively. Overall, our study presented an independent-of-ambient-light, highly accurate, and easily implementable navigation method for mobile chassis in commercial chicken farming houses, with significant potential for future research in mobile robotics within animal farming environments.

Experimental co–infection of infectious bronchitis and low pathogenic avian influenza viruses (H9N2) aggravates morbidity and mortality in commercial broiler chickens

Experimental co–infection of infectious bronchitis and low pathogenic avian influenza viruses (H9N2) aggravates morbidity and mortality in commercial broiler chickens

Performance of Commercial Broilers under Separate Sex Rearing and Feeding during the Finisher Period

The performance of commercial broiler chicken was evaluated under separate sex rearing and feeding during the finisher stage (22-42 days age). A total of 210, (21 days-old) commercial broilers were randomly allocated to five groups, viz., A (male & female mixed), B (male), C (male), D (female), and E (female) containing 42 birds in each group. The birds from groups A, C, and E were fed with a commercial broiler finisher diet containing 3250 kcal ME/kg, 19.5% CP, 1.00% Dig. Lysine (Dig. Lys) and 0.49% Dig. Methionine (Dig, Met). The males in group B were fed a special male diet containing 3000 kcal ME/kg, 18% Crude Protein (CP), and females from group D were fed a special female diet containing 3100 kcal ME/kg, 19.5 % CP. The Dig. Lys and Dig. Met levels in group B and D finisher diets were 2% higher than in group A. The results of the study concluded that the separate sex rearing of broilers may be followed by feeding special finisher diets to males (B) and females (D) to achieve similar body weight, weight gain, and feed efficiency to that of males (C) and females fed with a commercial finisher diet. Separate sex rearing of commercial broilers with special feeding is more economical than commercial diets fed to mixed and separate sex. Females fed on a special finisher diet had significantly (P < .05) higher serum total protein, albumin, and A/G ratio than males fed on a special finisher diet.

Feeding flaxseed to chicken hens changes the size and fatty acid composition of their chicks' brains.

Diets fed to commercial chicken breeders are high in n-6 fatty acids (n-6 FAs) and low in n-3 fatty acids (n-3 FAs). N-3 FAs are essential for embryonic brain development. In precocial birds, like chickens, brain development and brain n-3 FA accrual occur primarily before hatching. In two experiments, broiler and layer breeders were fed diets with or without flaxseed as the source of n-3 FAs from plant-based alpha-linolenic acid. Day-old broiler (n = 80) and layer (n = 96) offspring were dissected to calculate the percentage brain-to-body weight. Brain FA analyses from total lipid extracts were determined in the broiler (n = 24) and layer (n = 24) offspring brains, and the percentage FA composition and concentration (µg FAs per g brain) were calculated for each n-3 and n-6 FA. The brain size was only increased in broiler offspring from mothers fed flaxseed (χ2 = 9.22, p = 0.002). In layer offspring only, the maternal flaxseed diet increased the brain concentration and percentage of n-3 FAs and decreased n-6 FAs (p < 0.05). We showed that feeding flaxseed to mothers increased the brain size in broiler offspring and altered brain FA composition in layer offspring. These results may have implications for poultry and other captive bird species fed diets low in n-3 FAs.

Hypoxia-mediated programmed cell death is involved in the formation of wooden breast in broilers

BackgroundWooden breast (WB) myopathy is a common myopathy found in commercial broiler chickens worldwide. Histological examination has revealed that WB myopathy is accompanied by damage to the pectoralis major (PM) muscle. However, the underlying mechanisms responsible for the formation of WB in broilers have not been fully elucidated. This study aimed to investigate the potential role of hypoxia-mediated programmed cell death (PCD) in the formation of WB myopathy.ResultsHistological examination and biochemical analysis were performed on the PM muscle of the control (CON) and WB groups. A significantly increased thickness of the breast muscle in the top, middle, and bottom portions (P<0.01) was found along with pathological structure damage of myofibers in the WB group. The number of capillaries per fiber in PM muscle, and the levels of pO2 and sO2 in the blood, were significantly decreased (P < 0.01), while the levels of pCO2 and TCO2 in the blood were significantly increased (P < 0.05), suggesting hypoxic conditions in the PM muscle of the WB group. We further evaluated the PCD-related pathways including autophagy, apoptosis, and necroptosis to understand the consequence response to enhanced hypoxic conditions in the PM muscle of birds with WB. The ratio of LC3 II to LC3 I, and the autophagy-related factors HIF-1α, BNIP3, Beclin1, AMPKα, and ULK1 at the mRNA and protein levels, were all significantly upregulated (P < 0.05), showing that autophagy occurred in the PM muscle of the WB group. The apoptotic index, as well as the expressions of Bax, Cytc, caspase 9, and caspase 3, were significantly increased (P < 0.05), whereas Bcl-2 was significantly decreased (P < 0.05) in the WB-affected PM muscle, indicating the occurrence of apoptosis mediated by the mitochondrial pathway. Additionally, the expressions of necroptosis-related factors RIP1, RIP3, and MLKL, as well as NF-κB and the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, were all significantly enhanced (P < 0.05) in the WB-affected PM muscle.ConclusionsThe WB myopathy reduces blood supply and induces hypoxia in the PM muscle, which is closely related to the occurrence of PCD including apoptosis, autophagy, and necroptosis within myofibers, and finally leads to abnormal muscle damage and the development of WB in broilers.

Degree of hydrolysis of chicken versus plant-based chicken analogues: An in vitro digestion comparison

The adoption of plant-based meat analogues is increasing as an alternative to real meat products among consumers because they offer a more ecologically friendly and sustainable source of protein while also alleviating the ethical concerns related to livestock rearing and slaughter (1). However, there are concerns regarding plant-based meat analogues in terms of its nutritional quality, particularly their protein digestibility. This study aims to compared between chicken and plant-based chicken analogues in terms of nutritional composition and degree of protein hydrolysis.Proximate analyses were performed for raw and cooked samples to assess protein, fat, and energy concentrations in two chicken samples (breast and thigh) and four commercial plant-based chicken (P-C1[Wheat Protein 37%, Pea Protein 10%], P-C2 [ Soya Protein 63%], P-C3 [ Soya and Wheat Protein 83%], and P-C4 [Soya Protein 30%, Pea Protein 2%]). As a first step, the proximate analyses were assessed for the averaged samples, then the product-cooking interactions was assessed using a one-way ANOVA followed by Tukey test (p &lt;0.05). In vitro digestion was performed following the INFOGEST harmonised static in vitro digestion model (2) for cooked samples. After digestion, o- Phthaldialdehyde (OPA) assay was carried out to measure the degree of protein hydrolysis for each sample, and two-way ANOVA test was performed.Protein content of chicken was higher compared with the plant-based chicken, whereas fat content and energy concentrations were higher in plant-based chicken. The protein content of chicken was higher for raw and cooked samples (raw: 19.8 ± 0.38 g/100 g; cooked: 30.55 ± 4 g/100g), compared with plant-based chicken (raw: 13.8 ± 5.3 g/100 g; cooked: 23.4 ± 4.5 g/100g). Plant-based chicken have a higher fat content and energy concentrations for raw and cooked samples (raw:6.52 ± 1.5 g/100 g; cooked: 9.6 ± 3.17 g/100g) and (raw:189.4 ± 28.1 g/100 g; cooked: 291.3 ± 48.1 g/100g) respectively; compared to chicken fat content (raw:4.6 ± 2.7 g/100 g; cooked: 6.1 ± 4 g/100g) and energy concentration (raw:150.9 ± 25.4 g/100 g; cooked: 228.3 ± 20.7 g/100g). The product-cooking interactions showed a significant increase (P ≤0.0001) in the protein content (raw: 15.6 ± 2.3g/100g to 19.8 ± 0.74 g/100g; cooked: 21.4 ± 0.55 g/100g to 33.06 ± 0.71 g/100g), and fat content P&lt;0.001 (raw: 2.7 ± 0.06 g/100g to 8.3 ± 0.27 g/100g; cooked: 3.29 ± 0.19 g/100g to 13.22 ± 0.33 g/100g) in both chicken and plant-based chicken samples. No significant product-cooking interactions on energy content was found. The results from a two-way ANOVA test of the OPA and the degree of hydrolysis analyses demonstrated a significant increase in the degree of hydrolysis of chicken samples compared with plant-based chicken (P&lt;0.0001).The degree of hydrolysis and digestibility of chicken and chicken analogues was influenced by protein type, nutrient composition, and processing. These findings would provide substantial information for the improvement of plant-based chicken products with enhanced nutritional profiles. This work will be extended to investigate the availability and digestibility of individual amino acids.

Assessment of biosecurity status of commercial chicken farms from Maharashtra, India

Assessment of biosecurity status of commercial chicken farms from Maharashtra, India

A Study on the Selection Attributes and Preference of Active Seniors for Commercial Chicken Porridge

A Study on the Selection Attributes and Preference of Active Seniors for Commercial Chicken Porridge

Changes in the Transcriptome Profile in Young Chickens after Infection with LaSota Newcastle Disease Virus.

Understanding gene expression changes in chicks after vaccination against Newcastle Disease (ND) can reveal vaccine biomarkers. There are limited data on chicks' early immune response after ND vaccination. Two trials focused on this knowledge gap. In experiment one, 42 13-day-old specific-pathogen-free (SPF) chicks were used. Harderian glands (Hgs) and tracheas (Tcs) from five birds per group were sampled at 12, 24, and 48 h post-vaccination (hpv) to evaluate the gene transcription levels by RNA sequencing (RNA-seq) and RT-qPCR. The results of RNA-seq were compared by glmFTest, while results of RT-qPCR were compared by t-test. With RNA-seq, a significant up-regulation of interferon-related genes along with JAK-STAT signaling pathway regulation was observed in the Hgs at 24 hpv. None of the differentially expressed genes (DEGs) identified by RNA-seq were positive for RT-qPCR. Experiment 2 used 112 SPF and commercial chickens that were 1 day old and 14 days old. Only the commercial birds had maternal antibodies for Newcastle Disease virus (NDV). By RNA-seq, 20 core DEGs associated with innate immunity and viral genome replication inhibition were identified. Genes previously unlinked to NDV response, such as USP41, were identified. This research present genes with potential as immunity biomarkers for vaccines, yet further investigation is needed to correlate the core gene expression with viral shedding post-vaccination.

Infectious Coryza in Pennsylvania.

Infectious coryza (IC) is a respiratory disease of chickens, including pullets, layers, and broilers, caused by the bacteria Avibacterium paragallinarum (AP), which was previously known as Hemophilus gallinarum. IC classically causes production decreases and mortality in chickens, frequently paired with swelling of the sinuses, mucoid nasal discharge, and respiratory rales. Although IC is considered an endemic disease of chickens in California, it has been unusual to rare in commercial chickens in Pennsylvania. The last reported IC case in Pennsylvania was in 2002, involving broiler breeders. However, between December 2018 and December 2019, 68 farms were affected by IC in Pennsylvania, involving approximately 14 million birds. Several farms had multiple flocks affected. Most affected farms housed layer chickens (37/68), but a smaller number of broiler farms, pullet farms, and layer breeder farms have been affected. Ages of affected birds and duration of disease were variable between flocks, as were the severity of clinical signs, pathologic lesions, and rates of mortality. PCR testing has greatly aided and sped diagnostic efforts in addition to traditional bacterial culture. In eight layer cases and five broiler cases, bacterial culture of the sinus or choanal cleft proved unrewarding, whereas culture of trachea, air sacs, lungs, heart, or liver were diagnostic. Although cases of IC in commercial Pennsylvania poultry continue, they have been greatly reduced because of implementation of a successful vaccination program. In this case series report we detail epidemiologic, clinical, and pathologic aspects of this outbreak and discuss vaccination as a control measure of IC in the state of Pennsylvania.

Characterizing the domestic-wild bird interface through camera traps in an area at risk for avian influenza introduction in Northern Italy

Direct or indirect interactions between sympatric wildlife and poultry can lead to interspecies disease transmission. Particularly, avian influenza (AI) is a viral epidemic disease for which the poultry-wild bird interface shapes the risks of new viral introductions into poultry holdings. Given this background, the study hereby presented aimed to identify wild bird species in poultry house surroundings and characterize the spatiotemporal patterns of these visits. Eight camera traps were deployed for a year (January to December 2021) in three commercial chicken layer farms, including free-range and barn-type setups, located in a densely populated poultry area in Northern Italy at high risk for AI introduction via wild birds. Camera traps’ positions were chosen based on wildlife signs identified during preliminary visits to the establishments studied. Various methods, including time series analysis, correspondence analysis, and generalized linear models, were employed to analyze the daily wild bird visits. A total of 1,958 camera trap days yielded 5,978 videos of wild birds from 27 different species and 16 taxonomic families. The animals were predominantly engaged in foraging activities nearby poultry houses. Eurasian magpies (Pica pica), ring-necked pheasants (Phasianus colchicus) and Eurasian collared doves (Streptopelia decaocto) were the most frequent visitors. Mallards (Anas platyrhynchos), an AI reservoir species, were observed only in a farm located next to a fishing sport lake. Time series analysis indicated that wild bird visits increased during spring and winter. Farm and camera trap location also influenced visit frequencies. Overall, the results highlighted specific species that could be prioritized for future AI epidemiological surveys. However, further research is required to assess their susceptibility and infectivity to currently circulating AI viruses, essential for identifying novel bridge hosts.

Weak purifying selection in allelic diversity of the ADSL gene in indigenous and local chicken breeds and red junglefowl in Thailand

High levels of purine and uric acid, which are associated with health issues such as gout and cardiovascular disease, are found in the meat of fast-growing broiler chickens, which raises concerns about the quality of chicken meat and the health of the consumers who consume it. High genetic homogeneity and uniformity, particularly in genes involved in the synthesis of inosine monophosphate (IMP) and subsequent process of purine synthesis, which are associated with the meat quality, are exhibited in commercial broiler chickens owing to intensive inbreeding programs. Adenosine succinate lyase (ADSL) is a key enzyme involved in de novo purine biosynthetic pathway and its genetic polymorphisms affect IMP metabolism and purine content. In this study, we investigated the polymorphism of the ADSL gene in indigenous and local chicken breeds and red junglefowl in Thailand, using metabarcoding and genetic diversity analyses. Five alleles with 73 single nucleotide polymorphisms in exon 2, including missense and silent mutations, which may act on the synthesis efficiency of IMP and purine. Their protein structures revealed changes in amino acid composition that may affect ADSL enzyme activity. Weak purifying selection in these ADSL alleles was observed in the chicken population studied, implying that the variants have minor fitness impacts and a greater probability of fixation of beneficial mutations than strong purifying selection. A potential selective sweep was observed in Mae Hong Son chickens, whose purine content was lower than that in other breeds. This suggests a potential correlation between variations of the ADSL gene and reduced purine content and an impact of ADSL expression on the quality of chicken meat. However, further studies are required to validate its potential availability as a genetic marker for selecting useful traits that are beneficial to human health and well-being.

Genetic characteristics and selection signatures between Southern Chinese local and commercial chickens

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.

Dust sprinkling as an effective method for infecting layer chickens with wild-type Salmonella Typhimurium and changes in host gut microbiota.

Role of dust in Salmonella transmission on chicken farms is not well characterised. Salmonella Typhimurium (ST) infection of commercial layer chickens was investigated using a novel sprinkling method of chicken dust spiked with ST and the uptake compared to a conventional oral infection. While both inoculation methods resulted in colonisation of the intestines, the Salmonella load in liver samples was significantly higher at 7 dpi after exposing chicks to sprinkled dust compared to the oral infection group. Infection of chickens using the sprinkling method at a range of doses showed a threshold for colonisation of the gut and organs as low as 1000 CFU/g of dust. Caecal content microbiota analysis post-challenge showed that the profiles of chickens infected by the sprinkling and oral routes were not significantly different; however, both challenges induced differences when compared to the uninfected negative controls. Overall, the study showed that dust sprinkling was an effective way to experimentally colonise chickens with Salmonella and alter the gut microbiota than oral gavage at levels as low as 1000 CFU/g dust. This infection model mimics the field scenario of Salmonella infection in poultry sheds. The model can be used for future challenge studies for effective Salmonella control.

Low levels of chicken body louse (Menacanthus stramineus) infestations affect chicken welfare in a cage-free housing system

BackgroundThe chicken body louse is an obligate ectoparasite of domestic chickens. Chicken body lice feed on feathers, and infestation with this louse is linked to decreases in egg production, hen weight, and feed conversion efficiency. However, it is unknown how chicken body lice impact egg-laying chickens in cage-free environments. Welfare and behavior metrics were collected from flocks of egg-laying chickens either infested with chicken body lice or left uninfested.MethodsIn two trials, two flocks of cage-free commercial egg-laying chickens were infested with chicken body lice or maintained as uninfested controls. At three timepoints, behavior and welfare of all chickens was measured. On-animal sensors were used to quantify pecking, preening, and dustbathing behavior. Other animal-based welfare metrics included recording comb wounds and skin lesions.ResultsBirds infested with chicken body lice exhibited significantly more preening behaviors than uninfested birds, even at low louse levels. Moderate or severe skin lesions were detected on birds that were moderately infested with chicken body lice while skin lesions were never detected on uninfested birds.ConclusionsThe welfare of chickens was impacted by the chicken body louse, a chewing louse that primarily feather feeds. Evidence of skin lesions on infested birds suggests that lice may cause more damage to birds than previously thought, and further evaluation of louse economic damage is necessary.Graphical