To compare the physical and chemical changes in egg whites during storage, assisting in the evaluation of differences in egg freshness between various chicken breeds, we chose 240 blue-shelled eggs (Blue group) and 240 commercial brown-shelled eggs (Brown group) that 28-week-old hens had laid. In this study, all eggs were stored at 25 °C. The egg weight, egg components’ weight and proportion, Haugh Unit value and the contents of S-ovalbumin, ovomucin and lysozyme in the thick albumen (KA) and thin albumen (NA) were measured at eight time points every 3 days until the 21st day of storage. The eggshell, yolk and KA proportions in the Brown group were significantly lower, whereas the NA proportion was significantly higher than that in the Blue group (p < 0.001). The Haugh Unit value and S-ovalbumin in the Brown group were significantly higher, whereas KA ovomucin and NA lysozyme were significantly lower than those in the Blue group (p < 0.001). There existed significant negative correlations between the KA and NA, irrespective of weight or proportion. The Haugh Unit value was significantly positively correlated with lysozyme and ovomucin, but significantly negatively correlated with S-ovalbumin. During storage, the KA weight (proportion), Haugh Unit value, lysozyme and ovomucin decreased, whereas the NA weight (proportion) and S-ovalbumin increased. At each time point, the NA lysozyme in the Brown group was lower than that in the Blue group (p < 0.05). After storage for 6 days, the KA ovomucin in the Brown group began to be lower than that in the Blue group (p < 0.05). The study showed that the weight (proportion) differences in egg components between blue-shelled eggs and commercial brown-shelled eggs are mainly due to the NA. The Haugh Unit value and albumin protein indexes of blue-shelled eggs were better than those of brown-shelled eggs, and showed mild changes during storage, indicating the better storage performance of blue-shelled eggs.

This study reveals the physicochemical, microbial, flavor, and sensory changes in sauced duck from the marinating phase to the end of storage, divided into six stages (stages A–F). The changes in color, total plate count, total volatile basic nitrogen, and thiobarbituric acid reactive substance at different stages were clarified. We utilized 16S rRNA gene sequencing, GC-IMS, and GC-MS to explore the changes in bacterial flora, fatty acid composition, and flavor characteristics. The dominant bacteria identified in stages A–C included Psychrobacter, Flavobacterium, and Pseudomonas, while Lactobacillus and Staphylococcus dominated during stages D–F. Aldehydes, esters, alcohols, and ketones emerged as the main flavor compounds. Several unsaturated fatty acids significantly (p < 0.05) decreased from stage A to stage F. The sensory quality of sauced duck improved. The potential reactions were determined, and correlation analysis of sauced duck samples across different stages was performed. 3-Methy-1-butanol could be a crucial indicator of sauced duck’s overall quality. This research could support the treatment optimization of sauced duck products.

Egg production traits are major breeding targets, but their genetic architecture remains poorly characterized in indigenous chickens. In this study, seven egg production traits were measured in the WG chicken line: age at first egg (AFE), egg number at 21–25 (EN21–25W), 26–30 (EN26–30W), 31–35 (EN31–35W), and 36–43 weeks of age (EN36–43W), total egg number from 21 to 43 weeks of age (TEN), and average clutch length (ACL). Heritability and genetic correlations among seven egg production traits were estimated. Genome-wide association studies (GWASs) were performed using mixed linear model (MLM) and FarmCPU, followed by multiple trait fine-mapping with mvSuSiE. Variants were prioritized based on posterior inclusion probability (PIP) and proportion of phenotypic variance explained (PVE), and genes were prioritized for further investigation based on their positions within linkage disequilibrium-defined QTL intervals. Heritability estimates ranged from 0.19 (EN26–30W) to 0.74 (EN36–43W). AFE was moderately to strongly negatively correlated with other traits ($r_g$ = −0.37 to −0.93), whereas genetic correlations between egg numbers across laying stages were strongly positively correlated. GWASs identified 26 significant SNPs within 24 independent regions across 14 chromosomes. Multi-trait fine-mapping prioritized 25 SNPs, among which rs732088229 showed the strongest evidence of pleiotropic effects. Seven genes (NHLH2, MAFB, SYNDIG1, BNC1, TFPI2, EDNRB, and GSS) were prioritized for further investigation based on QTL delimitation and functional annotation. These findings provide potential markers for improving egg production and support the application of multiple trait fine-mapping to reproductive traits in poultry.