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Compared to high-yield commercial laying hens, Chinese indigenous chicken breeds have poor egg laying capacity due to the lack of intensive selection. However, as these breeds have not undergone systematic selection, it is possible that there is a greater abundance of genetic variations related to egg laying traits. In this study, we assessed 5 egg number (EN) traits at different stages of the egg-laying period: EN1 (from the first egg to 23 wk), EN2 (from 23 to 35 wk), EN3 (from 35 to 48 wk), EN4 (from the first egg to 35 wk), and EN5 (from the first egg to 48 wk). To investigate the molecular mechanisms underlying egg number traits in a Chinese local chicken breed, we conducted a genome-wide association study (GWAS) using data from whole-genome sequencing (WGS) of 399 Laiwu Black chickens. We obtained a total of 3.01 Tb of raw data with an average depth of 7.07 × per individual. A total of 86 genome-wide suggestive or significant single-nucleotide polymorphisms (SNP) contained within a set of 45 corresponding candidate genes were identified and found to be associated with stages EN1-EN5. The genes vitellogenin 2 (VTG2 ), lipase maturation factor 1 ( LMF1 ), calcium voltage-gated channel auxiliary subunit alpha2delta 3 ( CACNA2D3 ), poly(A) binding protein cytoplasmic 1 ( PABPC1 ), programmed cell death 11 ( PDCD11 ) and family with sequence similarity 213 member A ( FAM213A ) can be considered as the candidate genes associated with egg number traits, due to their reported association with animal reproduction traits. Noteworthy, results suggests that VTG2 and PDCD11 are not only involved in the regulation of EN3, but also in the regulation of EN5, implies that VTG2 and PDCD11 have a significant influence on egg production traits. Our study offers valuable genomic insights into the molecular genetic mechanisms that govern egg number traits in a Chinese indigenous egg-laying chicken breed. These findings have the potential to enhance the egg-laying performance of chickens. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of Lactobacillus salivarius ( L. salivarius ) SNK-6 supple-mentation on the laying performance, egg quality, blood parameters, intestinal morphology, and cecal microbial community of laying hens. A total of 432 healthy 30-wk-age laying hens were randomly divided into 3 groups with 6 replicates under the same husbandry and dietary regimes: control (CON); 2.0 × 108 CFU/kg L. salivarius supplementation (T1); 2.0 × 109 CFU/kg L. salivarius supplementation (T2). The experiment lasted for 10 wk. The results indicated that the supplementation resulted in a significant reduction in the broken egg and unqualified egg ratios, and a significant increase in the eggshell strength, eggshell relative weight, albumen height, and Haugh units (P < 0.05). The L. salivarius -treated hens exhibited significantly reduced serum malondialdehyde levels (P < 0.05); significantly increased total protein, phosphorus, calcitonin, and immunoglobulin M (P < 0.05); significantly increased cecal secretory immunoglobulin A concentration (P < 0.05); significantly improved villus height (VH) in the duodenum and VH to crypt depth ratio in the jejunum (P < 0.05). The serum globulin and interleukin-1β, immunoglobulin G concentrations, and catalase activity significantly increased in T2 (P < 0.05). Furthermore, the serum interferon-α level in T1 was significantly higher than that of the CON (P < 0.05). The intestinal barrier-related mRNA gene ZO-1, CLDN1 , and MUC2 expression in the jejunum was significantly upregulated in the T1 and T2 groups (P < 0.05). The Firmicutes/Bacteroidetes ratio was higher and the relative abundances of Flavonifractor and Clostridiales_noname were significantly higher in the T1 group (P < 0.05). In conclusion, dietary supplementation with L. salivarius SNK-6 may improve hen egg quality, serum antioxidant capacity, immune function, and intestinal health. [ABSTRACT FROM AUTHOR]

Avian leukosis virus (ALV) is a tumor-inducing virus that spreads among most chicken species, causing serious financial losses for the poultry industry. Subgroup J avian leukosis virus (ALV-J) is a recombinant exogenous ALV, which shows more extensive host range in comparison with other subgroups, especially in Chinese local chickens. To identify the relationship between ALV-J host range and the polymorphism of its cellular receptors, we performed a wide range epidemiological investigation of current ALV-J infection in Chinese local chickens, and discovered that all the 18 local chicken breeds being investigated from main local chicken breeding provinces were ALV-J positive. Furthermore, we cloned ALV-J cellular receptor genes of chNHE1 and chANXA2 of these 18 chicken breeds. Sequence alignment demonstrated that despite several regular mutations at the nucleotide level, there were no corresponding amino acid mutations for either chNHE1 gene or chANXA2 gene. Additionally, virus entry assay indicated that the level of viral enter into cells is stable among different chicken breeds. Results of this study indicated that the wide host range of ALV-J in Chinese local chickens was partially due to the high conservatism of its cellular receptors, and also provide target sites for drug design of resistance to ALV-J infection. [ABSTRACT FROM AUTHOR]

Abdominal fat is the major adipose tissue in chickens. In chicken, the deposition of abdominal fat affects meat yield and quality. Previous reports suggest that gut microbiota composition and function are associated with lipid metabolism. In this study, we used comparative metagenomics and metabolomics analysis to determine the gut microbiota and gut-host metabolite profiles in Shouguang (SG ; a Chinese chicken breed with low-fat deposition) and Luqin (LQ ; a fatty-type chicken breed with a fast growth rate) chickens. The results showed that LQ chickens had higher body weight, eviscerated yield, abdominal fat yield, abdominal fat ratio, and triglyceride (TG) content in the breast muscle than SG chickens. Untargeted metabolomics analyses showed a total of 11 liver metabolites, 19 plasma metabolites, and 30 cecal metabolites differentially enriched in LQ and SG chickens based on variable importance in the projection (VIP) ≥ 1 and P ≤ 0.05. These metabolites are involved in lipid and amino acid metabolism. The relative abundance of bacteria in the microbiota differed significantly between the 2 chicken breeds. The functional prediction of microbiota abundant in LQ chickens was starch and lactose degradation. Erysipelatoclostridium was abundant in LQ chickens and significantly positively correlated to palmitoyl ethanolamide (PEA), a key regulator of lipid metabolism. Our findings revealed differences in liver and plasma metabolites between chicken breeds with different adipose deposition capacities. Long-chain acylcarnitines might be important markers of adipose deposition differences in chickens. The cecum's microbial communities and metabolome profiles significantly differed between LQ and SG chickens. However, the relationship between cecal microbiota and their metabolites and liver and plasma metabolites is not thoroughly understood. Future research will focus on relating tissue metabolite changes to intestinal microbiota and their effects on body fat deposition. [ABSTRACT FROM AUTHOR]