Transcriptional analyses provide novel insights into the transgenerational effects of Poly (I:C) on chickens.

Pathogenic microorganisms that are ubiquitous in the environment threaten human health and food safety. Polyinosinic:polycytidylic acid (Poly (I:C)) is a macromolecule with a double-stranded RNA structure, which is often used to simulate viruses. Our previous study found that Poly (I:C) maternal stimulation could affect the reproduction of laying hens and their offspring, but the underlying mechanism needed to be explored. In the present study, splenic transcriptomes were sequenced and analyzed from two groups (Poly (I:C) treatment as the challenged group and saline treatment as the control) and in three generations (maternal stimulated F0 hens, unchallenged F1 and F2 generations). The results showed that Poly (I:C) maternal stimulation affected gene expression patterns in laying hens and their offspring. A total of 27 differentially expressed genes (DEGs) with the same regulating trend were discovered in the F0 and F1 generations, indicating an influence of the intergenerational transmission effect. Functional enrichment analysis of Gene Ontology (GO) showed that lymphocyte differentiation, positive regulation of leukocyte differentiation, positive regulation of MAPK cascade, and T cell differentiation were the common biological processes between F0 and F1 generations, revealing Poly (I:C) could affect the immunity of the treated F0 hens and the unchallenged subsequent generations. Further study showed that pathways associated with growth, development, biosynthesis, and metabolism of F2 chicks were also affected by Poly (I:C) maternal stimulation. Correlation analysis between DEGs and reproductive traits revealed that PHLDA2 (pleckstrin homology-like domain family A member 2) and PODN (podocan) with inheritable effect were highly correlated with egg-laying rate and egg weight in F1 hens, suggesting their potential long-term role in regulating reproductive traits. ARHGAP40, FGB, HRH4, PHLDA2, PODN, NTSR1, and NMU were supposed to play important roles in regulating chickens' immunity and reproductive traits. This study reveals the far-reaching effect on transcriptome induced by Poly (I:C), reflecting the influence of the mother's living environment on the offspring. It is an important reference for future research into the multi-generational transmission of maternal stimulation and harmful environmental factors.

Long-lasting effects of lipopolysaccharide on the reproduction and splenic transcriptome of hens and their offspring.

Lipopolysaccharide (LPS) is ubiquitous in the environment and is released after the death of gram-negative bacteria, which may be related to inflammation and immunosuppression. However, its impact on the reproduction of animals and their offspring, especially the underlying mechanism need further elucidation. Here, we used laying hens as a model organism to investigate the effects of maternal exposure to LPS (LPS maternal stimulation) on animal and their offspring's immunity and reproductive performance, as well as the regulatory role of the transcriptome. We found that the LPS maternal stimulation could reduce the egg-laying rate of hens and their offspring, especially during the early and late laying stages. The transcriptome study of the spleen in F0, F1 and F2 generations showed that the maternal stimulation of the LPS affects the patterns of gene expression in laying hens, and this change has a long-lasting effect. Further analysis of DEGs and their enrichment pathways found that the LPS maternal stimulation mainly affects the reproduction and immunity of laying hens and their offspring. The DEGs such as AVD, HPS5, CATHL2, S100A12, EXFABP, RSFR, LY86, PKD4, XCL1, FOS, TREM2 and MST1 may play an essential role in the regulation of the immunity and egg-laying rate of hens. Furthermore, the MMR1L3, C3, F13A1, LY86 and GDPD2 genes with heritable effects are highly correlated with the egg-laying rate, may have an important reference value for further research. Our study reveals the profound implications of LPS exposure on immunity and reproduction of offspring, elaborating the impact of immune alteration on the egg-laying rate, emphasizing the regulatory role of intergenerational transmission of the transcriptome, implying that the environment parents being exposed to has an important impact on offspring.

Diversity analysis of the bacterial community in tobacco waste extract during reconstituted tobacco process.

Reconstituted tobacco sheet process has been developed to treat and reuse tobacco wastes in the industry. During this process, microorganisms in original and concentrated tobacco waste extract (TWE) might play important roles in the final quality of the reconstituted tobacco. However, microbial communities in TWE remain largely unknown. In the present study, the Roche 454 bar-coded pyrosequencing was applied to analyze the bacterial community structure in samples. Comparison based on 16S rRNA gene sequences showed that the original and concentrated solutions of TWE harbored abundant bacteria probably resistant to the acid, high nicotine concentration, and high osmotic pressure environment. The dominant phyla were Firmicutes and Proteobacteria. Lactobacillus and Lysinibacillus were the dominant genera of Firmicutes. The most interesting genus of Proteobacteria was Pseudomonas. It is the first time to reveal the bacterial diversities on the TWE samples from the process of reconstituted tobacco sheets.

Metabolomics Reveals Glycerophospholipids, Peptides, and Flavonoids Contributing to Breast Meat Flavor and Benefit Properties of Beijing-You Chicken.

Unique metabolites contribute to the performance of meat flavor and potential function. In this study, UHPLC-Q Exactive HF-X-based metabolomics and multivariate analysis were applied to explore the characteristic metabolites in the breast meat of Beijing-You chicken (BYC) aged 150, 300, and 450 days (D150, D300, and D450). Based on the criteria of variable importance in the projection (VIP) > 1 and p < 0.05, a total of 154 and 97 differential metabolites (DMs) were screened out compared with D450 (D450 vs. D150, D450 vs. D300), respectively. In general, the relative content of carnosine, L-L-homoglutathione, demethyloleuropein, neohesperidin dihydrochalcone, 7-chloro-2-(3,4-dimethoxyphenyl)-3,5-dihydroxy-6,8-dimethoxy-4H-chromen-4-one, glycerophospholipids, exhibited the highest abundance at D450, while balenine, anserine, L-beta-aspartyl-L-leucine, glutathione, oxidized glutathione, stearoylcarnitine, ganoderic acid alpha, oleuroside, Lysoglycerophospholipid species (LGP) presented a downward trend with age. These 210 DMs were involved in 10 significantly enriched pathways related to the synthesis and metabolism of amino acids, peptides, and glycerophospholipid, such as glutathione metabolism, histidine metabolism, glycerophospholipid metabolism, arginine biosynthesis, tyrosine metabolism, and lysine degradation. In conclusion, this work could not only facilitate a better understanding of the differences of chicken flavor and benefit properties with age, but also provide potential valuable bioactive compounds for further research.

Dietary Crude Protein and Lysine Levels Affect Meat Quality and Myofiber Characteristic of Slow-Growing Chicken.

This study aimed to investigate the effects of dietary crude protein (CP) and lysine levels on growth performance, slaughter performance, meat quality, and myofiber characteristics of slow-growing chicken. A 3 × 3 factorial experiment was arranged, and the chickens were fed with 3 levels of dietary CP (16.0%, 17.0%, 18.0%) and 3 levels of dietary lysine (0.69%, 0.84%, 0.99%). A total of 540 8-week-old Beijing-You Chicken (BYC) female growing chickens were randomly allocated to 9 groups, 5 replicates per group, and 12 chickens per replicate. The birds were randomly allocated to one of the 9 experimental diets. Growth performance, slaughter performance, meat quality, and myofiber characteristics were determined at 16 weeks of age. The results showed that dietary CP level and the interaction of dietary CP and lysine levels affected average feed intake (AFI) (p < 0.05). The AFI in the 16.0% CP and 17.0% CP groups was higher than in the 18.0% CP group (p < 0.05). Dietary CP levels significantly affected body weight gain (BWG) (p < 0.05) at 9 to 16 weeks. The 18.0% CP group had the highest BWG (93.99 g). Dietary CP levels affected the percentage of leg muscle yield, and the percentage of leg muscle yield of the 16.0% CP group was significantly lower than that in the other two groups (p < 0.05). Dietary CP and lysine levels alone and their interactions did not affect pH24h, drip loss, and cooking loss of breast muscle (p > 0.05). The shear force of the 18.0% CP group (29.55 N) was higher than that in the other two groups (p < 0.01). Dietary CP level affected myofiber characteristic (p < 0.01), with the lowest myofiber density (846.35 p·mm-2) and the largest myofiber diameter (30.92 µm) at 18.0% CP level. Dietary lysine level affected myofiber diameter, endomysium thickness, perimysium thickness (p < 0.01), with the largest myofiber diameter (29.29 µm) obtained at 0.84% lysine level, the largest endomysium thickness (4.58 µm) at 0.69% lysine level, and the largest perimysium thickness (9.26 µm) at 0.99% lysine level. Myofiber density was negatively correlated with myofiber diameter and endomysium thickness (R = -0.883, R = -0.523, p < 0.01); perimysium thickness had a significant negative correlation with shear force (R = -0.682, p < 0.05). Therefore, reducing dietary CP level and adding appropriate lysine can reduce myofiber diameter and increase perimysium thickness, reducing shear force and improving meat tenderness. A high lysine level (0.99%) in the low-CP (16.0%) diet can improve meat tenderness by regulating the myofiber characteristic without affecting production performance.

The detection and elimination of flavin-containing monooxygenase 3 gene T329S mutation in the Beijing You chicken.

In this study, using a newly developed TaqMan-based real-time PCR method for the T329S mutation in the flavin-containing monooxygenase 3 (FMO3) gene, a marker-assisted selective breeding program against the unfavorable T allele was implemented in the Beijing You chicken breeding stock from 2010 to 2012. A total of 2,359 breeder candidate chickens were detected. After 1-generation culling in both males and females and 2-generation culling only in males, genotyping results in 2013 showed that there still remained a low unfavorable allele frequency of 0.022 in this population. The results indicated that to ensure a complete eradication of the defective tainting mutation in FMO3 out of the Beijing You population, more strict breeding and management schemes should be carried out in the future.

Whole Genome Resequencing Revealed the Genetic Relationship and Selected Regions among Baicheng-You, Beijing-You, and European-Origin Broilers.

As the only two You-chicken breeds in China, Baicheng-You (BCY) and Beijing-You (BJY) chickens are famous for their good meat quality. However, so far, the molecular basis of germplasm of the two You-chicken breeds is not yet clear. The genetic relationship among BCY, BJY, and European-origin broilers (BRs) was analyzed using whole genome resequencing data to contribute to this issue. A total of 18,852,372 single nucleotide polymorphisms (SNPs) were obtained in this study. After quality control, 8,207,242 SNPs were applied to subsequent analysis. The data indicated that BJY chickens possessed distant distance with BRs (genetic differentiation coefficient (FST) = 0.1681) and BCY (FST = 0.1231), respectively, while BCY and BRs had a closer relationship (FST = 0.0946). In addition, by using FST, cross-population extended haplotype homozygosity (XP-EHH), and cross-population composite likelihood ratio (XP-CLR) methods, we found 374 selected genes between BJY and BRs chickens and 279 selected genes between BCY and BJY chickens, respectively, which contained a number of important candidates or genetic variations associated with feather growth and fat deposition of BJY chickens and potential disease resistance of BCY chickens. Our study demonstrates a genome-wide view of genetic diversity and differentiation among BCY, BJY, and BRs. These results may provide useful information on a molecular basis related to the special characteristics of these broiler breeds, thus enabling us to better understand the formation mechanism of Chinese-You chickens.

Proteomic Profiling of Thigh Meat at Different Ages of Chicken for Meat Quality and Development.

Chicken age contributes to the meat characteristics; however, knowledge regarding the pathways and proteins associated with meat quality and muscle development are still scarce, especially in chicken thigh meat. Hence, the objective of this study was to elucidate the intricate relationship between these traits by liquid chromatography mass spectrometry at three different ages. A total of 341 differential expressed proteins (DEPs) were screened out (fold change ≥ 1.50 or ≤0.67 and p < 0.05) among 45 thigh meat samples (15 samples per age) of Beijing-You chicken (BYC), collected at the age of 150, 300, or 450 days (D150, D300, and D450), respectively. Subsequently, based on the protein interaction network and Markov cluster algorithm (MCL) analyses, 91 DEPs were divided into 26 MCL clusters, which were associated with pathways of lipid transporter activity, nutrient reservoir activity, signaling pathways of PPAR and MAPK, focal adhesion, ECM-receptor interaction, the cell cycle, oocyte meiosis, ribosomes, taurine and hypotaurine metabolism, glutathione metabolism, muscle contraction, calcium signaling, nucleic acid binding, and spliceosomes. Overall, our data suggest that the thigh meat of BYC at D450 presents the most desirable nutritional value in the term of free amino acids (FAAs) and intramuscular fat (IMF), and a series of proteins and pathways associated with meat quality and development were identified. These findings also provide comprehensive insight regarding these traits across a wide age spectrum.

Effects of Age on Compounds, Metabolites and Meat Quality in Beijing-You Chicken Breast Meat.

The physical properties, free amino acids, and metabolites of Beijing-You chicken (BYC) breast meat aged 90, 120, and 150 days were analyzed to investigate the flavor changes with age. The shear force and intramuscular fat increased from 90 to 120 days significantly. The contents of total free amino acids and essential amino acids decreased from 90 to 120 days significantly. No significant differences were detected between 120 and 150 days. The contents of sweet amino acids, bitter amino acids, and umami amino acids showed no significant differences between different ages. In addition, GC-MS and LC-MS were integrated for metabolite detection in breast meat. A total of 128, 142, and 88 differential metabolites were identified in the comparison groups of 120 d vs. 90 d, 150 d vs. 90 d, and 150 d vs. 120 d. Amino acids and lipids were the main differential metabolites. The pathway analysis showed that arginine biosynthesis, histidine metabolism, purine metabolism, and cysteine and methionine metabolism were the main pathways involved in flavor formation during BYC development. It was also found that the metabolites associated with flavor, such as methionine, cysteine, glucose, anserine, arachidonic acid, and glycerol 1-phosphate, were significantly affected by age.

Integration of GC-MS and LC-MS for metabolite characteristics of thigh meat between fast- and slow-growing broilers at marketable age.

Thigh meat from Cobb 500 broiler (Cobb) and Beijing-You chicken (BYC) at marketable age were compared to explore the impact of growth rate on meat quality. BYC had a higher water capacity, as well as lower shear forces and IMF content than Cobb, indicating that the growth rate has a significant influence on meat quality. Additionally, 144 upregulated and 44 downregulated differential metabolites were identified using gas chromatography mass spectroscopy (GC-MS) and liquid chromatography mass spectrometer (LC-MS). Moreover, we found a significant difference between the dominant expression of metabolites in the two genotypes. The highly expressed metabolites in Cobb were amino acids and their derivatives, including l-citrulline, dimethylglycine, 1,4-butanediamine, alanine, and creatine. In contrast, BYC deposited more bioactive compounds, such as, α-linolenic acid, linoleic acid, eicosapentaenoic acid, anserine, and taurine. These results indicate that meat quality and metabolite profiles differ greatly between fast- and slow-growing chickens.

Population Genomic Sequencing Delineates Global Landscape of Copy Number Variations that Drive Domestication and Breed Formation of in Chicken.

Copy number variation (CNV) is an important genetic mechanism that drives evolution and generates new phenotypic variations. To explore the impact of CNV on chicken domestication and breed shaping, the whole-genome CNVs were detected via multiple methods. Using the whole-genome sequencing data from 51 individuals, corresponding to six domestic breeds and wild red jungle fowl (RJF), we determined 19,329 duplications and 98,736 deletions, which covered 11,123 copy number variation regions (CNVRs) and 2,636 protein-coding genes. The principal component analysis (PCA) showed that these individuals could be divided into four populations according to their domestication and selection purpose. Seventy-two highly duplicated CNVRs were detected across all individuals, revealing pivotal roles of nervous system (NRG3, NCAM2), sensory (OR), and follicle development (VTG2) in chicken genome. When contrasting the CNVs of domestic breeds to those of RJFs, 235 CNVRs harboring 255 protein-coding genes, which were predominantly involved in pathways of nervous, immunity, and reproductive system development, were discovered. In breed-specific CNVRs, some valuable genes were identified, including HOXB7 for beard trait in Beijing You chicken; EDN3, SLMO2, TUBB1, and GFPT1 for melanin deposition in Silkie chicken; and SORCS2 for aggressiveness in Luxi Game fowl. Moreover, CSMD1 and NTRK3 with high duplications found exclusively in White Leghorn chicken, and POLR3H, MCM9, DOCK3, and AKR1B1L found in Recessive White Rock chicken may contribute to high egg production and fast-growing traits, respectively. The candidate genes of breed characteristics are valuable resources for further studies on phenotypic variation and the artificial breeding of chickens.

Breast Meat Fatty Acid Profiling and Proteomic Analysis of Beijing-You Chicken During the Laying Period.

The disparity in fatty acids (FA) composition exhibits a significant impact on meat quality, however, the molecular regulatory mechanisms underlying this trait in chicken are far from clear. In this study, a total of 45 female Beijing-You chicken (BYC) hens, fed on the same diet, were collected at the slaughter age of 150, 300, or 450 days (D150, D300, and D450) from sexual maturation stage to culling stage (15 birds per age). Gas chromatography-mass spectrometry (GC-MS) and tandem mass tag labeling technology based on liquid chromatography mass spectrometry (TMT-LC-MS/MS) analysis strategies were applied to profile FA compositions and to compare differential expressed proteins (DEPs) between these different slaughter ages, respectively. The FA profiling showed that increasing hen ages resulted in increased contents of both saturated and unsaturated fatty acids. Proteomic analyses showed a total of 4,935 proteins in chicken breast muscle with the false discovery rate (FDR) < 1% and 664 of them were differentially expressed (fold change > 1.50 or < 0.67 and P < 0.01). There were 410 up- and 116 down-regulated proteins in D150 vs. D300 group, 32 up- and 20 down-regulated in D150 vs. D450 group, and 72 up- and 241 down-regulated in D300 vs. D450 group. A total of 57 DEPs related to FA/lipid-related metabolisms were obtained according to the enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). These DEPs were involved in 21 significantly enriched (P < 0.05) pathways, including well-known pathways for FA synthesis (metabolism, desaturation, and elongation) and the signaling pathways for lipid metabolism (PPAR, adipocytokine, calcium, VEGF, MAPK, and Wnt). In addition, there existed several representative DEPs (FABP, FABP3, apoA-I, apoA-IV, apoC-III, apoB, VTG1, and VTG2) involved in the regulation of FA/lipid transportation. The construction of the interaction networks indicated that HADH, ACAA2, HADHA, ACSL1, CD36, CPT1A, PPP3R1, and SPHK1 were the key core nodes. Finally, eight DEPs were quantified using parallel reaction monitoring (PRM) to validate the results from TMT analysis. These results expanded our understanding of how the laying age affects the FA compositions and metabolism in hen breast meat.

UHPLC-QTOF/MS-based comparative metabolomics in pectoralis major of fast- and slow-growing chickens at market ages.

The molecular regulatory mechanism underlying meat quality between different chicken genotypes remains elusive. This study aimed to identify the differences in metabolites and pathways in pectoralis major (breast muscle) between a commercial fast-growing chicken genotype (Cobb500) and a slow-growing Chinese native chicken genotype (Beijing-You chickens, BYC) at market ages respectively based on ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry (UHPLC-QTOF/MS). Eighteen metabolites were identified as potential biomarkers between BYC and Cobb500 at market ages. Among them, L-cysteine exhibited a higher relative intensity in BYC compared with Cobb500 and was enriched into 10 potential flavor-associated KEGG pathways. In addition, the glycerophospholipid metabolism pathway was found to be associated with chicken meat flavor and the accumulation of sn-glycerol 3-phosphate and acetylcholine was more predominant in BYC than that in Cobb500, which were catalyzed by glycerophosphocholine phosphodiesterase (GPCPD1, EC:3.1.4.2), choline O-acetyltransferase (CHAT, EC:2.3.1.6), and acetylcholinesterase (ACHE, EC:3.1.1.7). Overall, the present study provided some metabolites and pathways for further investigating the roles of the differences in meat flavor quality in breast muscle between Cobb500 and BYC at market ages.

Comprehensive Proteomic Characterization of the Pectoralis Major at Three Chronological Ages in Beijing-You Chicken.

Chronological age is one of the important factors influencing muscle development and meat quality in chickens. To evaluate the protein expression profiles during skeletal muscle development, we performed a tandem mass tag (TMT)-based quantitative proteomic strategy in pectoralis major (breast muscle) of Beijing-You chicken (BYC) at the chronological age of 90, 120, and 150 days. Each chronological age contained 3 pooling samples or 15 birds (five birds per pooling sample). A total of 1,413 proteins were identified in chicken breast muscle with FDR < 1% and 197 of them were differentially expressed (fold change ≥1.2 or ≤0.83 and p < 0.05). There were 110 up- and 71 down-regulated proteins in 120 d vs 90 d group, 13 up- and 10 down-regulated proteins in 150 d vs 120 d group. The proteomic profiles of BYC at 120 d were very similar to those at 150 d and highly different from those at 90 d, suggesting that 120 d might be an important chronological age for BYC. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that these differentially expressed proteins were mainly involved in the pathway of glycolysis/gluconeogenesis, adrenergic signaling in cardiomyocytes, focal adhesion, oocyte meiosis and phagosome. Furthermore, some DEPs were quantified using parallel reaction monitoring (PRM) to validate the results from TMT analysis. In summary, these results provided some candidate protein-coding genes for further functional validation and contribute to a comprehensive understanding of muscle development and age-dependent meat quality regulation by proteins in chickens.

Removal of roosters alters the domestic phenotype and microbial and genetic profile of hens.

Hens are raised apart from roosters in modern poultry production, a substantial change from their natural social structure. We compared productivity, injuries, behavior, physiology, microbiome and transcriptome of hens housed with (R+) or without (R-) roosters to quantify the effects of this change in social structure. Hens were raised free-range from 70 to 280 days when 30 birds per treatment were assigned to battery cages until Day 315 (R+C vs. R-C), while 30 birds per treatment remained in free-range pens (R+F vs. R-F). Response to a novel environment and object, behavioral time budgets, cecum microbiome, blood composition and transcriptomic sequencing of thigh muscle and spleen were analyzed. Hens housed without roosters showed better survival, consumed less food, produced more eggs and had better feed conversion. R+F hens clustered around the rooster and were less mobile in the novel environment and object tests. R+F hens displayed the richest microbiome, and the presence of roosters resulted in differentially expressed genes related to muscle development, cellular processes, environmental information processing and immune function. Removing roosters from housed hens intensified desirable characteristics favored by domestication probably operating by deprivation of mating behavior and reduced fear, along with altered microbial and genetic function.

Enhanced production of CoQ10 by newly isolated Sphingomonas sp. ZUTEO3 with a coupled fermentation-extraction process.

The use of coenzyme Q(10) (CoQ(10)) as a complementary therapy in heart failure will increase in proportion to the growth of the ageing population and the expansion of statins consumption. Economical production of CoQ(10) by microbes will become more important due to the growing demands of the pharmaceutical industry. Process simplification and integration might be one desirable pathway for economic production of CoQ(10) by microbial fermentation. In this report, the effect of a coupled fermentation-extraction process on CoQ(10) production by newly isolated Sphingomonas sp. ZUTEO3 was evaluated. It was found that the CoQ(10) yield of the coupled process was significantly higher than that of the traditional process. As optimal conditions in our experiment, 2% soybean oil was added to the original culture to enhance cell membrane permeability, and 50 mL hexane was added to the 30 h culture as an extracting solvent for the subsequent coupled fermentation-extraction process. The maximal yield of CoQ(10) reached 43.2 mg/L and 32.5 mg/g dry cell weight after 38 h of total fermentation period. The coupled process represents one potential pathway for CoQ(10) production with even higher yield and lower cost. This is the first report of CoQ(10) production by Sphingomonas sp. using a coupled fermentation-extraction process.

[Isolation, characterization and fermentation condition of coenzyme Q10 producing strain with solanesol as precursor].

A bacterium capable of producing Coenzyme Q10 (CoQ10, was isolated from soil. Based on analysis of the 16S rDNA sequence, traditional physiological characteristics, and Biolog-GN, the strain was belonging to the genus Sphingomonas and named as Sphingomonas sp. ZUTEO3. The optimum fermentation condition of CoQ10 production was as following: glucose 15 g/L, (NH4)2SO4 10 g/L, original pH 8.0 and at 25 degrees C. The addition of solanesol could improve CoQ10 production. The optimal condition for the bioconservation from solanesol to CoQ10 was as following: adding 0.75 g/L of raw solanesol after the first 12 h fermentation and continued for another 12 h fermentation. The maximal yield of CoQ10 reached 96.88 mg/L.

Transcriptome changes provide genetic insights into the effects of rearing systems on chicken welfare and product quality.

Farm animals raised under free-range (FR) systems are assumed to have improved welfare and higher-quality products that are better to eat than intensively reared animals. However, the modulations are limited in scientific investigations. In this study, we compared 2 rearing systems (FR and cage) and their effects on chickens, including production performance, product quality, body condition, physiological indicators, and gene expression. By using a match-mismatch design in which each treatment was transferred to the other treatment during the last period of the experiment, we aimed to understand the influence of current and former rearing conditions and the ability of individuals to adapt to the current environment. The results indicated that the FR system led to better chicken welfare (e.g., gait score, feather condition, and physiological indicators, P < 0.05) and contributed to higher product quality (P < 0.05), although it resulted in poorer production performance (P < 0.05) and foot pad condition (P < 0.05) than that of the cage rearing system. Additionally, the FR system triggered a series of inner changes and genetic responses in chickens, such as the upregulation of calcium and GnRH signaling, actin and cytoskeleton regulations, immune functions, and developmental processes, and the downregulation of pathological regulations (q-value < 0.05 for all gene ontology terms and P < 0.05 for all Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways). In conclusion, rearing systems alter chicken gene expression patterns, which provide a genetic basis for the adaptability to rearing environments and ultimately affects chicken welfare and products.

Free Dietary Choice and Free-Range Rearing Improve the Product Quality, Gait Score, and Microbial Richness of Chickens.

Poultry welfare has been extensively studied; however, there is a lack of rigorous scientific knowledge relating to the different aspects of welfare factors and how this may contribute to the production quantity and product quality as well as the welfare of chickens. Therefore, we conducted an integrated study to compare welfare factors in chickens by providing free dietary choice under cage rearing, and further comparing cage rearing with free-range rearing. One hundred chickens each were allocated to a cage rearing group with conventional feeding (CC), a cage rearing group with free dietary choice of mealworms (FDM), a cage rearing group with free dietary choice of mealworms and fresh grass (FDMG), and a free-range rearing system group with free dietary choice of mealworms and fresh grass (FRMG). Results showed that under cage rearing, free dietary choice contributed to better meat quality and gait score, higher values of blood platelets, and a richer gut microbial composition, but poorer egg production than CC chickens. As compared to FDMG, FRMG chickens showed better meat quality, gait score, and feather conditions, as well as a richer gut microbial composition; however, they had poorer egg production and a poorer foot pad and foot feather condition. We conclude that free dietary choice and free-range rearing systems improve the product quality, gait score, and microbial richness of chickens.

Association of SNP rs80659072 in the ZRS with polydactyly in Beijing You chickens.

The Beijing You chicken is a Chinese native breed with superior meat quality and a unique appearance. The G/T mutation of SNP rs80659072 in the Shh long-range regulator of GGA2 is highly associated with the polydactyly phenotype in some chicken breeds. In the present study, this SNP was genotyped using the TaqMan detection method, and its association with the number of toes was analyzed in a flock of 158 birds of the Beijing You population maintained at the Beijing Academy of Agriculture and Forestry Sciences. Furthermore, the skeletal structure of the digits was dissected and assembled in 113 birds. The findings revealed that the toes of Beijing You chickens were rich and more complex than expected. The plausible mutation rs80659072 in the zone of polarizing activity regulatory sequence (ZRS) in chickens was an essential but not sufficient condition for polydactyly and polyphalangy in Beijing You chickens. Several individuals shared the T allele but showed normal four-digit conformations. However, breeding trials demonstrated that the T allele could serve as a strong genetic marker for five-toe selection in Beijing You chickens.