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Introduction: Investigating the genetic footprints of historical temperature selection can get insights to the local adaptation and feasible influences of climate change on long-term population dynamics. Object: Chicken is a significative species to study genetic adaptation on account of its similar domestication track related to human activity with the most diversified varieties. Yet, few studies have demonstrated the genetic signatures of its adaptation to naturally tropical and frigid environments. Method: Here, we generated whole genome resequencing of 119 domesticated chickens in China including the following breeds which are in order of breeding environmental temperature from more tropical to more frigid: Wenchang chicken (WCC), green-shell chicken (GSC), Tibetan chicken (TBC), and Lindian chicken (LDC). Results: Our results showed WCC branched off earlier than LDC with an evident genetic admixture between WCC and LDC, suggesting their closer genetic relationship. Further comparative genomic analyses solute carrier family 33 member 1 (SLC33A1) and thyroid stimulating hormone receptor (TSHR) genes exhibited stronger signatures for positive selection in the genome of the more tropical WCC. Furthermore, genotype data from about 3,000 African local ecotypes confirmed that allele frequencies of single nucleotide polymorphisms (SNPs) in these 2 genes appeared strongly associated with tropical environment adaptation. In addition, the NADH:ubiquinone oxidoreductase subunit S4 (NDUFS4) gene exhibited a strong signature for positive selection in the LDC genome, and SNPs with marked allele frequency differences indicated a significant relationship with frigid environment adaptation. Conclusion: Our findings partially clarify how selection footprints from environmental temperature stress can lead to advantageous genomic adaptions to tropical and frigid environments in poultry and provide a valuable resource for selective breeding of chickens.

Pyrroloquinoline quinone disodium (PQQ·Na2) has been considered a human food supplement for human health promotion with its antioxidant properties. To determine whether PQQ·Na2 had similar functions to improve the antioxidant ability of layers and eggs, 180 laying hens were fed with 0 or 0.4 mg/kg PQQ·Na2 diets. Supplementation with PQQ·Na2 increased the albumen height, Haugh unit of the eggs. PQQ·Na2 also led to a higher glutathione peroxidase (GSH-Px) concentration in plasma and a lower malondialdehyde (MDA) content in the liver and egg yolk. Similarly, liver gene and protein expression of nuclear factor erythroid 2-related 2 (Nrf2) and heme oxygenase 1 (HO-1) were up-regulated by PQQ·Na2. Moreover, PQQ·Na2 increased the abundance of Firmicutes, Microbacterium, Erysipelatoclostridium, Mailhella, Lachnospiraceae_UCG-010, and Herbaspirillum in gut. Overall, these results suggested PQQ·Na2 increased the antioxidant ability of layers and eggs which might be in connection with the activation of the Nrf2/HO-1 pathway and optimized gut microflora.

Fat has a high energy density, and excessive fatness has been recognized as a problem for egg production and the welfare of chickens. The identification of a genetic polymorphism controlling fat deposition would be helpful to select against excessive fatness in the laying hen. This study aimed to estimate genomic heritability and identify the genetic architecture of abdominal fat deposition in a population of chickens from a Dongxiang blue-shelled local breed crossbred with the White Leghorn. A genome-wide association study was conducted on abdominal fat percentage, egg production and body weights using a sample of 1534 hens genotyped with a 600 K Chicken Genotyping Array. The analysis yielded a heritability estimate of 0.19 ± 0.04 for abdominal fat percentage; 0.56 ± 0.04 for body weight at 72 weeks; 0.11 ± 0.03 for egg production; and 0.24 ± 0.04 for body weight gain. The genetic correlation of abdominal fat percentage with egg production between 60 and 72 weeks of age was −0.35 ± 0.18. This implies a potential trade-off between these two traits related to the allocation of resources. Strong positive genetic correlations were found between fat deposition and weight traits. A promising locus close to COL12A1 on chromosome 3, associated with abdominal fat percent, was found in the present study. Another region located around HTR2A on chromosome 1, where allele substitution was predicted to be associated with body weight gain, accounted for 2.9% of phenotypic variance. Another region located on chromosome 1, but close to SOX5, was associated with egg production. These results may be used to influence the balanced genetic selection for laying hens.

This experiment was conducted to study the effects of γ-amino butyric acid (GABA) on growth performance, blood biochemical indices and intestinal morphology of yellow-feathered broilers exposed to a high temperature environment. One hundred and forty four, 28-day-old male yellow-feathered broilers were separated into 2 groups with 6 replicates and 12 birds per replicate. The two experimental groups included: control group, which fed the basal diet, and GABA supplemented group, which fed the basal diet supplemented with 100 mg/kg GABA. After 7 days of feeding experimental diet at 26 °C, birds were fed the experimental diet and exposed to a high temperature environment at 35 °C and 60% RH for 14 days. Results revealed that average daily gain (ADG, p = .004) and average daily feed intake (ADFI, p = .003) of the GABA group were higher than control group, feed: gain ratio (F/G; p = .023) and mortality (p = .042) were lower than control group. The serum levels of glucose (GLU; p = .016), total cholesterol (T-CHO; p = .001), and low density lipoprotein (LDL; p = .001) as well as the activities of aspartate-aminotransferase (AST; p = .008), lactate dehydrogenase (LDH; p = .042) and creatine kinase (CK; p = .032) of the GABA group were lower than control group, while villus length (p = .016) of jejunum was higher than control group. In conclusion, adding 100 mg/kg GABA to diet can improve growth performance, reduce serum intracellular enzyme activities, protect the organs and intestinal morphology of yellow-feathered broilers exposed to a high temperature environment during 36-49 days of age.Highlights GABA improves growth performance of yellow-feathered broilers exposed to a high temperature environment. GABA protects the intestine of yellow-feathered broilers exposed to a high temperature environment.

The high-throughput chromosome conformation capture (Hi-C) technique is widely used to study the functional roles of the three-dimensional (3D) architecture of genomes. However, the knowledge of the 3D genome structure and its dynamics during extreme environmental adaptations remains poor. Here, we characterized 3D genome architectures using the Hi-C technique for chicken liver cells. Upon comparing Lindian chicken (LDC) liver cells with Wenchang chicken (WCC) liver cells, we discovered that environmental adaptation contributed to the switching of A/B compartments, the reorganization of topologically associated domains (TADs), and TAD boundaries in both liver cells. In addition, the analysis of the switching of A/B compartments revealed that the switched compartmental genes (SCGs) were strongly associated with extreme environment adaption-related pathways, including tight junction, notch signaling pathway, vascular smooth muscle contraction, and the RIG-I-like receptor signaling pathway. The findings of this study advanced our understanding of the evolutionary role of chicken 3D genome architecture and its significance in genome activity and transcriptional regulation.

An experiment was conducted to evaluate the effects of cyclic heat stress on phenotypic response, meat quality and muscle glycolysis of broiler. One hundred and eighty 35-day-old male Xueshan broilers with similar BW were randomly selected and exposed to either thermal neutral (TN; 23 °C, 55–60% RH, n = 6) or heat stress conditions (CHS; cyclic temperatures of 35 °C from 10:00 to 18:00, 32 °C from 18:00 to 20:00, 28 °C from 20:00 to 08:00, and 32 °C from 08:00 to 10:00 at 40–45% RH, n = 6) for 7 days. Relative to broilers under thermoneutral conditions, broilers subjected to cyclic heat stress had an overall increase in rectal temperature and respiration rate (p

An experiment was conducted to evaluate the effects of crude protein (CP) levels on growth performance, carcase quality, meat quality, immune indices, litter and faeces quality, as well as welfare quality, in free-range yellow broilers using balanced amino acid technology. In total, 600 one-d-old Suqin yellow broilers were raised for 21 d. On d 22, 540 birds with similar BW (390 ± 7 g SD) were randomly selected and placed into 9 pens (3 groups with 3 replicates per group and 60 birds each replicate) and then reared to 56 d of age. The birds were fed a diet containing CP 19% (control), 18% or 17% (measured value: 18.878%, 17.881%, 17.052%, respectively), in three groups for 35 d. The results revealed that decreasing dietary CP levels from 19% to 17% had no impact on broiler growth performance, carcase quality and meat quality (p > .05). The relative immune organ weights also showed no change to the lowering of dietary CP levels (p > .05), whereas serum albumin was significantly influenced by decreasing dietary CP levels (p = .042). Furthermore, nitrogen content in litter and faeces, as well as the footpad dermatitis score for welfare indices, were decreased with decreased dietary CP levels (p = .009, p = .014, p = .045, respectively). The results of this study suggest that low-protein diets with balanced amino acids reduce nitrogen excretion and footpad dermatitis without effecting the performance, carcase quality, and meat quality of free-range yellow broilers.

Differential lipid metabolic requirements of sexually-mature males and females may influence the regulation of lipid metabolism-associated genes and hence the content of adipose tissue. We measured the expression of eight lipid metabolism-associated genes (fatty acid synthase, FASN; acylglycerol- 3- phosphate O-acyltransferase 9, AGPAT9; peroxisomal proliferator-activated receptor γ, PPARγ; lipoprotein lipase, LPL; carnitine palmitoyl transferase 1 A, CPT1A; carnitine palmitoyl transferase 1 B, CPT1B; acyl-COA dehydrogenase long chain, ACADL; monoglyceride lipase, MGL) in eight tissues (hypothalamus, HYP; liver; heart; pectoralis major muscle, PM; gastrocnemius muscle, GAS; abdominal fat, AF; clavicular fat, CF; subcutaneous fat, SF) of five male and five female white feather chickens using real time PCR at 217 d (when the females were at peak egg production). There were no difference between sexes, nor were there sex by tissue interactions for CPT1A and MGL. In both cases expression was greater for liver than the other tissues. When interactions of sex by tissue were significant, the FASN mRNA abundance in HYP, liver, and PM was greater for females than males. There was no sexual dimorphism for any tissue for PPARγ. Overall values were greater for adipose depots than HYP and liver with muscles intermediate for AGPAT9. LPL mRNA abundance in PM and AF was greater for females than males, with the pattern reversed for heart and SF. CPT1B mRNA abundance in GAS and CF was greater for females than males, with the relationship reversed for liver. ACADL mRNA abundance in HYP, liver, and GAS was greater for females than males, and lower in PM than males.The results demonstrated that expression of lipid metablism-associated genes varies among sexes in mature chickens depending on the gene and the tissue.

This trial was conducted to evaluate the effects of high-dose daidzein supplements on laying performance, egg quality and antioxidation in laying hens during the late laying period. Seven hundred sixty eight 55-wk-old Hyline Brown were randomly assigned to four groups with 8 replicates of 24 birds each (192 laying hens per group) and fed diets supplemented with 0 (control), 10 mg/kg, 50 mg/kg and 100 mg/kg daidzein for 8 wk in the diets. Egg production, egg mass, feed conversion and egg yolk malondialdehyde were significantly effected by daidzein supplementation (P

Increasing evidence indicates that major depressive disorder (MDD) is usually accompanied by altered white matter in the prefrontal cortex, the parietal lobe and the limbic system. As a behavioral abnormity of MDD, rumination has been believed to be a substantial indicator of the mental state of the depressive state. So far, however, no report that we are aware of has evaluated the relationship between white matter alterations and the ruminative state. In this study, we first explored the altered white matter using a tract-based spatial statistics (TBSS) method based on diffusion tensor imaging of 19 healthy and 16 depressive subjects. We then investigated correlations between the altered white matter microstructure in the identified altered regions and the severity of ruminations measured by the ruminative response scale. Our results demonstrated altered white matter microstructure in circuits connecting the prefrontal lobe, the parietal lobe and the limbic system (p

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