Qingwu Xin

Liancheng white ducks have a distinctive “white feathers, black beak, and green feet” phenotype, making them a useful model for studying pigmentation traits in waterfowl. The previous study found that the F1 generation of Liancheng white ducks crossed with white-feathered ducks and hemp-feathered ducks were all gray-black in color. This indicates the specificity and complexity of melanin deposition in Liancheng white ducks, which makes the selection and breeding of pigment traits through phenotyping difficult. The aim of this study was to investigate the candidate transcriptomic regulatory signals of melanogenesis in Liancheng white ducks. Skin, mouth skin, foot skin, liver, and muscle samples were collected from 130-day-old Liancheng white ducks. Morphological differences were observed via histological analysis, and extraction-based pigment levels were determined. The results showed that melanin granules were clearly observed in tissues other than the liver and were distributed mainly in the basal layer of the epidermis and around feather follicles; the pigment values in the tissues decreased in the order mouth skin > liver > foot skin > muscle and skin. However, the relatively high liver value should be interpreted cautiously because obvious melanin granule deposition was not observed histologically. Whole-transcriptome sequencing was performed on mouth skin and skin samples. In total, 3074 differentially expressed genes (DEGs) were screened; upregulated genes associated with melanogenesis included melanocyte inducing transcription factor (MITF) and tyrosinase (TYR); downregulated genes included agouti signaling protein (ASIP) and adenylate cyclase 2 (ADCY2). Eighteen differentially expressed microRNAs (DEmiRNAs) were identified. Based on target prediction and pathway enrichment analysis, novel_290 and apl-miR-11588-3p were identified as candidate miRNAs potentially associated with melanogenesis-related pathways, and their predicted target genes included phosphatidylinositol 3-kinase (PI3K) and Janus kinase 1 (JAK1). Additionally, 364 differentially expressed long noncoding RNAs (DElncRNAs) were identified; TCONS_00063335 and TCONS_00019814 were identified as candidate lncRNAs potentially associated with melanogenesis-related genes, including TYR and TYRP1. A putative ceRNA network was constructed based on the predicted miRNA–mRNA and miRNA–lncRNA relationships, and ENSAPLT00000025522–apl-miR-11588-3p–MAPK8IP3 was identified as a candidate network relationship associated with MAPK-related pigmentation pathways. However, because this relationship was inferred mainly from bioinformatic prediction and expression association analysis, further functional validation is required to confirm whether it contributes to melanogenesis regulation. These findings provide candidate transcriptomic and noncoding RNA information for the further investigation of tissue-specific pigmentation in Liancheng white ducks.

Meat quality characteristics are important economic traits of ducks. To identify the molecular bases of these traits, we performed an integrated multi-omics analysis (metabolomics, transcriptomics, and miRNAomics) that compared the breast muscle of 300-day-old Liancheng white duck (LD), which is a lean-type breed prized for its soup flavor, and traditional meat duck Cherry Valley duck (CD), which is a fast-growing fat-type breed used for roasting. The results show that LD had higher levels of amino and bile acids, while CD had higher levels of carbohydrates. Integration analysis revealed key breed-specific molecular signatures. In LD, upregulation of the amino acid transporters SLC7A6 and SLC6A9 related to amino acid transport was consistent with elevated intramuscular amino acids. For carbohydrate metabolism, SOCS3—a well-established negative regulator of glucose uptake in mammalian skeletal muscle—was significantly upregulated in LD, consistent with their lower intramuscular carbohydrate levels. SLC6A9 and SOCS3 were predicted to be negatively regulated by oan-miR-1386. In LD, upregulation of the bile acid biosynthesis gene CH25H paralleled the higher bile acid content, suggesting complex, tissue-specific regulation of these pathways. This integrated analysis provides a resource for candidate genes, miRNAs, and metabolic pathways underlying breed-specific meat quality traits in ducks. The findings generate testable hypotheses for future functional studies and offer potential molecular targets for breeding strategies aimed at improving poultry meat quality.

25-Hydroxyvitamin D3 (25(OH)D3) has been reported to improve production performance and egg quality in ducks during the late laying period, but its effects during the peak laying period remain rarely studied. The aim of this study was to investigate the effects of dietary 25(OH)D3 supplementation on the production performance, egg quality, tibia quality, and mineral metabolism of ducks during the peak laying period in a cage rearing system. A total of 360 Liancheng white laying ducks at 30 weeks (wk) of age were randomly assigned to 5 groups, each consisting of 6 replicates with 12 ducks per replicate. Ducks were fed a basal diet with 25(OH)D3 supplementation at 0, 1,000, 2,000, 3,000, and 4,000 IU/kg throughout the trial for 8 wk. One-way ANOVA was employed to assess the influence of supplementation level, and linear and quadratic regression analyses were performed for statistical evaluation of dose-dependent effects. 25(OH)D3 supplementation linearly and quadratically increased the laying rate, average egg weight, and egg mass and quadratically decreased the feed conversion ratio (FCR). The mean of eggshell strength and thickness at 4 and 8 wk increased linearly and quadratically with increasing 25(OH)D3 levels, and the 4000 IU/kg 25(OH)D3 increasing the eggshell thickness by 5.7% (at 4 wk) and 2.9% (mean of those at 4 and 8 wk) relative to those of the non-supplemented group. At the end of weeks 4 and 8 of the trial, serum 25(OH)D3, bone glutamyl protein (BGP), and carbonic anhydrase (CA) increased linearly (P < 0.05), and serum parathyroid hormone (PTH) decreased linearly (P < 0.05); the 4000 IU/kg group had the highest serum 25(OH)D3 (4.24 ng/mL) and BGP (3.11 ng/mL) concentrations at 8 wk. Additionally, the tibial breaking strength, trabecular bone number, BGP content, alkaline phosphatase (ALP) activity, and mRNA levels increased linearly with 25(OH)D3 supplementation (P < 0.05). The optimal dietary 25(OH)D3 supplementation levels were approximately 2,355, 2,347 and 3,269 IU/kg on the basis of the quadratic model of the laying rate, FCR and eggshell strength, respectively. In summary, 25(OH)D3 supplementation improved the production performance and eggshell quality of ducks during the peak laying period by maintaining calcium and phosphorus homeostasis and enhancing tibia quality. A diet that contains 2,347–3,269 IU/kg of 25(OH)D3 displayed beneficial effects on maintaining calcium and phosphorus homeostasis and improving the tibial quality, which was recommended for ducks during peak laying period in the cage rearing system (30–38 wk of age).

This study aimed to investigate the effects of replacing soybean meal with an equivalent amount of fermented feed on the production performance of laying hens. A total of 480 healthy, 70-week-old Hy-Line Sonia laying hens were divided into three groups, with four replicates of 40 chickens in each group. The control group (NT) was fed a basal diet, while the experimental groups were fed with a diet in which soybean meal was replaced with an equivalent amount of fermented feed: 5 % replacement in treatment group 1 (TT1) and 10 % replacement in treatment group 2 (TT2). At 8 weeks after soybean meal replacement, the results showed that the abnormal egg rate in the 10 % fermented feed group was significantly reduced. Egg quality parameters, such as eggshell strength and thickness, significantly improved in both the TT1 and TT2 groups after 4 and 8 weeks of equivalent soybean meal replacement. The drip loss of breast muscle was significantly lower in the TT1 and TT2 groups compared to the NT group at both 4 and 8 weeks. In addition, there was a significant increase in the pH of thigh muscle at 0 h postmortem and a significant reduction in the fat and cholesterol contents in the muscles of laying hens in the TT1 and TT2 groups. Replacement of 10 % soybean meal with an equivalent amount of fermented feed for 8 weeks yielded a satisfactory effect.

Background: The very low density lipoprotein receptor gene ( VLDLR ), a member of the low density lipoprotein receptor ( LDLR ) gene family, plays a crucial role in the synthesis of yolk protein precursors in oviparous species. Differential splicing of this gene has been reported in human, rabbit and rat. In chicken, studies showed that the VLDLR protein on the oocyte surface mediates the uptake of yolk protein precursors into growing oocytes. However, information on the VLDLR gene in duck is still scarce. Methods: Full-length duck VLDLR cDNA was obtained by comparative cloning and rapid amplification of cDNA ends (RACE). Tissue expression patterns were analysed by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR). Association between the different genotypes and egg performance traits was investigated with the general linear model (GLM) procedure of the SAS ^® software package. Results: In duck, two VLDLR transcripts were identified, one transcript (variant-a) containing an O-linked sugar domain and the other (variant-b) not containing this sugar domain. These transcripts share ~70 to 90% identity with their counterparts in other species. A phylogenetic tree based on amino acid sequences showed that duck VLDLR proteins were closely related with those of chicken and zebra finch. The two duck VLDLR transcripts are differentially expressed i.e. VLDLR-a is mainly expressed in muscle tissue and VLDLR-b in reproductive organs. We have localized the duck VLDLR gene on chromosome Z. An association analysis using two completely linked SNP sites (T/C at position 2025 bp of the ORF and G/A in intron 13) and records from two generations demonstrated that the duck VLDLR gene was significantly associated with egg production (P < 0.01), age of first egg (P < 0.01) and body weight of first egg (P < 0.05). Conclusions: Duck and chicken VLDLR genes probably perform similar function in the development of growing oocytes and deposition of yolk lipoprotein. Therefore, VLDLR could be a candidate gene for duck egg performance and be used as a genetic marker to improve egg performance in ducks.