Phage therapy is widely being reconsidered as an alternative to antibiotics for the treatment of multidrug-resistant bacterial infections, including salmonellosis caused by Salmonella. As facultative intracellular parasites, Salmonella could spread by vertical transmission and pose a great threat to both human and animal health; however, whether phage treatment might provide an optional strategy for controlling bacterial vertical infection remains unknown. Herein, we explored the effect of phage therapy on controlling the vertical transmission of Salmonella enterica serovar Gallinarum biovar Pullorum (S. Pullorum), a poultry pathogen that causes economic losses worldwide due to high mortality and morbidity. A Salmonella phage CKT1 with lysis ability against several S. enterica serovars was isolated and showed that it could inhibit the proliferation of S. Pullorum in vitro efficiently. We then evaluated the effect of phage CKT1 on controlling the vertical transmission of S. Pullorum in an adult broiler breeder model. The results demonstrated that phage CKT1 significantly alleviated hepatic injury and decreased bacterial load in the liver, spleen, heart, ovary, and oviduct of hens, implying that phage CKT1 played an active role in the elimination of Salmonella colonization in adult chickens. Additionally, phage CKT1 enabled a reduction in the Salmonella-specific IgG level in the serum of infected chickens. More importantly, the decrease in the S. Pullorum load on eggshells and in liquid whole eggs revealed that phage CKT1 effectively controlled the vertical transmission of S. Pullorum from hens to laid eggs, indicating the potential ability of phages to control bacterial vertical transmission.

Skeletal muscle development and growth are closely associated with efficiency of poultry meat production and its quality. We performed whole transcriptome profiling based on RNA sequencing of breast muscle tissue obtained from Shouguang chickens at embryonic days (E) 12 and 17 to post-hatching days (D) 1, 14, 56, and 98. A total of 9,447 differentially expressed genes (DEGs) were filtered (Q < 0.01, fold change > 2). Time series expression profile clustering analysis identified five significantly different expression profiles that were divided into three clusters. DEGs from cluster I with downregulated pattern were significantly enriched in cell proliferation processes such as cell cycle, mitotic nuclear division, and DNA replication. DEGs from cluster II with upregulated pattern were significantly enriched in metabolic processes such as glycolysis/gluconeogenesis, insulin signaling pathway, calcium signaling pathway, and biosynthesis of amino acids. DEGs from cluster III, with a pattern that increased from E17 to D1 and then decreased from D1 to D14, mainly contributed to lipid metabolism. Therefore, this study may help us explain the mechanisms underlying the phenotype that myofiber hyperplasia occurs predominantly during embryogenesis and hypertrophy occurs mainly after birth at the transcriptional level. Moreover, lipid metabolism may contribute to the early muscle development and growth. These findings add to our knowledge of muscle development in chickens.

Producing translucent eggs has been found to reduce the quality and safety of the eggs, as well as the demand from consumers. However, the intestinal function and the molecular mechanism for the production of translucent eggs remain uncertain. A total of 120 eggs from 276-day-old Jining Bairi were divided into two groups based on eggshell translucence: the translucent egg group (group T) and the normal group (group C). Group T exhibited thicker eggshells and a lower egg yolk color. Subsequently, we divided the chickens into translucent and normal groups based on their egg quality. We then assessed the plasma biochemical index, intestinal morphology and structure, enzyme activity, and antioxidant capacity of the hens producing translucent eggs compared to those producing normal eggs. The results showed that the ratio of duodenal villus length to crypt depth, succinate dehydrogenase (SDH) activity, chymotrypsin, total ATPase (T-ATPase), alkaline phosphatase (AKP), and glutathione peroxidase (GSH-Px) activities were decreased in the hens produced translucent eggs (p < 0.05), but malondialdehyde (MDA) content was increased (p < 0.05); jejunal lipase activity, Na⁺K⁺-ATPase activity, total antioxidant capacity (T-AOC), and GSH-Px activities were decreased (p < 0.05) in group T; ileal amylase and Ca²⁺Mg²⁺-ATPase activities were also decreased (p < 0.05) in group T. In addition, we identified a total of 471 differentially expressed genes (DEGs) in duodenal tissue, with 327 up-regulated genes and 144 down-regulated genes (|log₂FC| ≥ 1 and p < 0.05). Enrichment analysis showed that the up-regulated genes, such as GSTT1, GSTO2, and GSTA3, were mostly enriched in metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450, and oxidative phosphorylation pathways. The results of our study indicate that plasma lipid metabolism disorder, decreased intestinal antioxidant capacity, and altered intestinal metabolism capabilities may influence the formation of translucent eggs.

The efficiency of molecular breeding largely depends on the cost of genotyping, which plays an important role in breeding and population genetic studies. Compared to pig, cattle, and sheep, poultry has a small size genome, and lower individual value. Developing a relatively low-density genotyping panel is needed to decrease the genotyping cost for poultries. In the present study, we developed a chicken 11 K single nucleotide polymorphism (SNP) genotyping panel for breeding and genetic analysis using genotyping by targeted sequencing (GBTS). The panel design was based on whole genome sequencing data from 7 local breeds and a commercial breed. In total 11,200 SNPs were included in the final chip. Population analyses of the eight breeds showed high SNP call rates and minor allele frequencies (MAF), enabling clear differentiation between populations. The families within population can also be identified. Additionally, the 11K panel was applied to a genomic prediction of Wenshang Barred chickens, the predictive ability and prediction accuracy between the WGS and chip dataset non-significantly differed. Therefore, the newly developed chicken low-density SNP is efficient, cost-effective, and well-suited for application in local Chinese chickens, which can accelerate chicken breeding improvements and enhance conservation efforts.

High-density SNP chips have been demonstrated to be effective instruments for simultaneously genotyping large numbers of loci, thereby facilitating genome-scale analyses and advancing genomic selection (GS) in poultry and livestock. The meat-type duck, an economically valuable poultry species in China, has so far lacked precise and high-throughput genotyping systems, which has constrained the broader implementation of GS and genome-wide association analyses (GWASs) and consequently slowed genetic progress. In this study, we developed and validated a novel SNP array based on Genotyping-by-Targeted-Sequencing (GBTS) technology. The array comprises 40,875 SNP markers evenly distributed across 32 duck chromosomes. Using data generated from this array, genomic heritability estimates were obtained for six economic traits in a cultured duck population (n = 400), with values of 0.61 ± 0.09, 0.69 ± 0.08, 0.80 ± 0.08, 0.11 ± 0.09, 0.14 ± 0.08, 0.31 ± 0.09 for age at first egg (AFE), egg production number at 38 weeks (EN38w), egg weight at 38 weeks (EW38w), body weight at 35 days (BW35d), shank length at 35 days (SL35d) and thickness of breast muscle at 40 days (TB40d). A total of 163 significant SNPs associated with economic traits were identified through GWAS, and annotation revealed 28 candidate genes related to five of these traits. Moreover, the prediction accuracy of ssGBLUP for AFE, EN38w, EW38w, BW35d, SL35d, and TB40d reached 0.55 ± 0.16, 0.56 ± 0.12, 0.57 ± 0.08, 0.25 ± 0.19, 0.31 ± 0.19, and 0.47 ± 0.17, respectively—values that exceeded those obtained using BLUP. Population genomic analyses of 400 ducks demonstrated that this SNP array provides improved genomic prediction accuracy over pedigree-based BLUP for most analyzed traits. Overall, the developed SNP array provides a robust, high-efficiency, and cost-effective genotyping platform that will accelerate genetic progress and promote the sustainable development of the meat-type duck industry.

Producing translucent eggs has been found to reduce the quality and safety of the eggs produced., as well as the demand from consumers. However, the intestinal function and the molecular mechanism for the production of translucent eggs remain uncertain. A total of 120 eggs were allocated into two groups, one for the translucent egg group (group T) and one for the normal group (group C), according to the degree of eggshell translucence. Translucent eggs showed thicker eggshell and lower egg yolk color. We also detected the plasma biochemical index, intestinal morphology and structure, enzyme activity, and antioxidant capacity of the hens’ producing translucent eggs and normal eggs. The results showed that the ratio of duodenal villus length to crypt depth, succinate dehydrogenase (SDH) activity, chymotrypsin, total ATPase (T-ATPase), alkaline phosphatase (AKP) and glutathione peroxidase (GSH-Px) activities were decreased in the hens produced translucent eggs (P < 0.05), but malondialdehyde (MDA) content was increased (P < 0.05); jejunal lipase activity, Na+K+-ATPase activity, total antioxidant capacity (T-AOC), GSH-Px activities were decreased (P < 0.05) in group T; ileal amylase and Ca2+Mg2+-ATPase activities were also decreased (P < 0.05) in group T. In addition, we identified a total of 471 differentially expressed genes (DEGs) in duodenal tissue, with 327 up-regulated genes and 144 down-regulated genes (|log2FC| ≥ 1 and P < 0.05). Enrichment analysis showed that the up-regulated genes, such as GSTT1, GSTO2, GSTA3, were mostly enriched in metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450 and oxidative phosphorylation pathways. The results of our study indicate that plasma lipid metabolism disorder, decreased intestinal antioxidant capacity, and altered intestinal metabolism capabilities may influence the formation of translucent eggs.