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The Tibetan chicken (Gallus gallus) provides high quality protein and iron for humans, which shows many phenotypic adaptations to the low oxygen. Study of the genetic mechanisms of circular RNAs (circRNAs) in hypoxia adaptation has not been reported. Four embryonic heart tissue samples from Tibetan chickens and Daheng broilers were collected. Differentially expressed circRNAs (DEcircRNAs) were identified via high-throughput sequencing. Bioinformatic analysis was used to indicate the functions and pathways of the DEcircRNAs. A total of 29 DEcircRNAs were identified between 4 Tibetan chickens and 4 Daheng broilers, including 15 upregulated and 14 downregulated DEcircRNAs in Tibetan chickens. GO analysis revealed that the DEcircRNAs were mainly involved in lung development or oxygen metabolism, such as ubiqunegative regulation of mesenchymal cell proliferation involved in lung development, oxidoreductase activity, and peroxisome. Pathway analysis showed that DEcircRNAs were mainly enriched in oxidative phosphorylation, tight junction, VEGF/MAPK/PPAR/Ras/PI3K-Akt signaling pathway. We also constructed a circRNA-miRNA-mRNA-pathway network to visualize the regulatory relationship associated with hypoxia adaptation of the tight junction pathways. The circRNA expression profile was obtained to complement the current Tibetan chicken circRNA database and provides new information for future studies into biological adaptation to hypoxic stress in the Tibetan chicken.

Follicular atresia is an important cause of reproductive decline in egg-laying hens. Therefore, a better understanding of the regulation mechanism of follicle atresia in poultry is an important measure to maintain persistent high egg performance. However, how the role of the regulatory relationship between autophagy and apoptosis in the intrafollicular environment affects the follicular atresia of chickens is remain unclear. The objective of this study was to explore the regulatory molecular mechanisms in regard to follicular atresia. 20 white leghorn layers (32-wk-old) were equally divided into 2 groups. The control group was fed freely, and the experimental group induced follicular atretic by fasting for 5 d. The results showed that the expression of prolactin (PRL) levels was significantly higher in the fasted hens, while the levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were lower. Most importantly, RNA sequencing, qPCR, and Western blotting detected significantly elevated levels of autophagy and apoptosis markers in atresia follicles. Interestingly, we found that fibromodulin (FMOD) levels was significantly lower in follicles from fasted hens and that this molecule had an important regulatory role in autophagy. FMOD silencing significantly promoted autophagy and apoptosis in granulosa cells, resulting in hormonal imbalance. FMOD was found to regulate autophagy via the transforming growth factor beta (TGF-β) signaling pathway. Our results suggest that the increase in autophagy and the imbalance in internal homeostasis cause granulosa cell apoptosis, leading to follicular atresia in the chicken ovary. This finding could provide further insight into broodiness in chicken and provide avenues for further improvements in poultry production.

Additional file 2: Fig. S2. GO analysis of differentially expressed miRNA target genes.

Previous studies have shown that the feather growth rate of chicks is determined by two alleles located on the sex chromosome Z; however, in chicken production, feathering is usually not consistently controlled by the sex chromosome. To identify whether the feathering rate is related to autosomal inheritance, whole-genome resequencing was performed in eight chickens with slow- and fast-feathering rate. A total of 54,984 autosomal single nucleotide polymorphisms (SNPs) were identified, including 393 and 376 exonic SNPs in slow-feathering and fast-feathering chickens, respectively. Mutated genes were mainly involved in response to stimuli and growth and reproduction processes. Mutated genes related to slow-feathering rate were mainly involved in wingless-type MMTV integration site signaling pathway and mitogen-activated protein kinase signaling pathway, whereas mutated genes associated with fast-feathering rate were primarily enriched in autophagy, calcium signaling pathway, extracellular matrix-receptor interaction, and Focal adhesion processes. Importantly, two SNPs, involved in feather development, were found in the exonic regions of Wnt signaling genes. These results shed new light on the relationship between genetic mutation and feather growth rate from the perspective of autosomal inheritance and may have economic significance in chicken breeding.

Additional file 1: Fig. S1. miRNA expression TPM density distribution map.

This study was conducted to evaluate the effects of stocking density on productive performance, egg quality, and antioxidant capacity in laying ducks. A total of 720 20-week-old Jinding laying ducks were randomly assigned to 5 stocking densities (4, 5, 6, 7, and 8 birds/m2) with 8 replicate pens each treatment. The results showed that increasing stocking density linearly increased egg production and egg mass and linearly decreased FCR of laying ducks (P

Backgroud Studies have shown that prebiotics could affect meat quality, but the underlying mechanism are poorly understood. This study aimed to investigate whether prebiotics affect chicken’s meat quality through gut microbiome and metabolome. Methods The gut content were collected from chickens fed with or without prebiotics (galactooligosaccharides or xylo-oligosaccharides) and subjected to microbiome and metabolome analyses, and chicken breast was performed transcriptome sequencing. Results The prebiotics altered proportions of microbiota in gut contents at different levels, especially microbiota in the phylum of Bacteroidetes and Firmicutes, such as genus of Alistipes, Bacteroides, and Faecalibacterium. The prebiotics also altered contents of caecal metabolites such as lysophosphatidylcholine (lysoPC), intramuscular fat and flavor compound (Benzaldehyde and myristic acid). Differentially expressed genes (DEGs) induced by prebiotics were significantly involved in regulation of lipolysis inadipocytes and adipocytokine signaling pathway. Changes in gut microbiota and metabolites were remarkably correlated such as Bacteroidetes and Firmicutes was respectively positively and negatively correlated with lysoPC. DEGs were also interacted with caecal metabolites. Conclusion These findings integrated and incorporated link among gut microbiota, metabolites and transcriptome, which proposed prebiotics may affect meat quality and flavor of chickens.

Probiotics are expected to be an ideal alternative for antibiotics in the poultry industry. This study aimed to investigate the effect of Lactobacillus plantarum on growth traits, slaughter performance, serum markers and intestinal bacterial community of Daheng broilers. A total of 2400 healthy one-day-old Daheng broilers were randomly divided into 5 groups with 6 replicates per group and 40 individuals per replicate. Birds in control group were fed a basal diet, and others were fed basal diets supplemented with 105 , 106 , 107 and 108 CFU/kg Lactobacillus plantarum, respectively. It turned out that adding Lactobacillus plantarum to diet could significantly improve the serum immune performance of broilers (p 0.05), but had no significant effect on growth traits and slaughter performance. Moreover, Lactobacillus plantarum could improve the diversity of intestinal bacterial community, but with the increase of addition concentration, the diversity would gradually decrease. In conclusion, Lactobacillus plantarum can be used as feed additive in broiler production, but whether it is more effective than antibiotics needs further investigation.

Free-range broiler production is an effective combination of ecological and economic benefits which should be further standardized. The purpose of this study was to evaluate the effects of free-range broiler production on ecosystem by measuring the changes in vegetation characteristics and soil physicochemical properties under different stocking densities. A natural meadow with rich biodiversity was created and further divided into three groups. The broilers were reared in door and provided range access around 6 to 22 weeks of age with two different densities, 600 and 1200 broilers/ha. The vegetation characteristics and soil physicochemical properties, such as total coverage, soil nutrition and pH value, were measured at the beginning and the end of stocking. The results showed that the vegetation characteristics and soil physicochemical properties changed significantly after free-range stocking. The dominant plants, total coverage, richness index, diversity and biomass above-ground of treatment groups illustrated a considerable difference comparing with those in control group, and the indicators of soil physicochemical properties in treatment groups increased remarkably except the pH value. The present study demonstrated the higher stocking density would cause a more serious destruction of vegetation characteristics and modification of soil physicochemical properties, which suggested that an even lower stocking density or an alternative management such as rotational grazing could be a better choice for free-range broiler production.

The introduction of forage grass in poultry industry had double benefit on animals and the environment. In this study, three kinds of pastures were planted artificially to evaluate their roles through the determination of grass, chicken and soil-related indexes. The results showed that raising chickens under the forest could destroy vegetation and affect the chemical properties of soil negatively. Changes of soil caused by chickens can be alleviated through planting grass. Forage provided a certain food source for chickens without affecting the growth, slaughter properties, meat quality, immune indexes and other performances. Suitable pasture should have good regeneration ability, trampling resistance, good palatability, and do not cause harm to the health of chickens.

In order to satisfy the healthy growth and performance of livestock and poultry, a large amount of energy is often consumed in the production process of modern livestock and poultry breeding, which is used for automatic feeding management and regulation of breeding environment. In this study, based on the ISO 13790 5R1C equivalent resistance capacitance network computing model, using the henhouse heat balance, water balance, balance of gas (ammonia, carbon dioxide concentration) principle, we developed a simple closed loop control henhouse environment and energy consumption prediction model, Through on-site validation tests, the results show that the model is reliable, and it can assist the farmer for breeding planning, house-design process and increase environmental control and energy management efficiency.

Hypoxia affects the physiology of cells and organisms; however, the mechanisms associated with hypoxia adaptation remain unknown in Tibetan chickens. In this study, we aimed to identify long noncoding RNAs (lncRNAs) involved in hypoxia adaptation in Tibetan chickens and Daheng broilers, to provide insights into the mechanisms underlying hypoxia induction. RNA sequencing results revealed that a total of 5504 lncRNAs and 16,779 microRNAs were differentially expressed in four Tibetan chickens and four Daheng broilers; 70 lncRNAs were up-regulated and 113 lncRNAs were down-regulated in the Tibetan chickens compared to the expression levels in the Daheng broilers. The differentially expressed lncRNAs (DElncRNAs) were enriched in the following Gene ontology terms: protein complex localization, small-molecule metabolic process, and RNA splicing. Kyoto Encyclopedia of Genes and Genomes analyses revealed that the DElncRNAs were mainly enriched in pathways that regulate cell junctions and intercellular spaces and oxygen or energy metabolism, mainly involved in hypoxic adaption. Moreover, a predicted ceRNA network with five DElncRNAs interacted with three miRNAs that acted on 42 pathways through 19 target genes. Quantitative real-time polymerase chain reaction was used to verify that the expression levels of ENSGALG00000008047, ENSGALG00000050044, and ENSGALG00000053982 were significantly lower in Tibetan chickens than in the Daheng broilers, consistent with the RNA sequencing results. We obtained lncRNA expression profiles for the heart tissue of Tibetan chickens for the first time and have provided novel data that may aid research on biological adaptation to hypoxic stress. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-020-02272-8) contains supplementary material, which is available to authorized users.