Effect of organic and inorganic dietary selenium supplementation on gene expression in oviduct tissues and Selenoproteins gene expression in Lohman Brown-classic laying hens

Background The oviduct of a hen provides a conducive environment for egg formation, which needs a large amount of mineral elements from the blood via trans-epithelial permeability. Eggshell is the calcified layer on the outside of an egg that provides protection and is critical for egg quality. However, little is known about the genes or proteins involved in eggshell formation, and their relationship to dietary microminerals. We hypothesized that dietary selenium supplementation in chickens will influence genes involved in eggshell biomineralization, and improve laying hen antioxidant capacity. The objective of this research was to investigate how organic and inorganic dietary selenium supplementation affected mRNA expression of shell gland genes involved in eggshell biomineralization, and selenoproteins gene expression in Lohman Brown-Classic laying hens. Results Shell gland (Uterus) and liver tissue samples were collected from hens during the active growth phase of calcification (15–20 h post-ovulation) for RT-PCR analysis. In the oviduct (shell gland and magnum) and liver of laying hens, the relative expression of functional eggshell and hepatic selenoproteins genes was investigated. Results of qPCR confirmed the higher (p < 0.05) mRNA expression of OC-17 and OC-116 in shell gland of organic Se hen compared to inorganic and basal diet treatments. Similarly, dietary Se treatments affected the mRNA expression of OCX-32 and OCX-36 in the shell gland of laying hens. In the magnum, mRNA expression of OC-17 was significantly (p < 0.05) higher in hens fed-bacterial organic, while OC-116 mRNA expression was down-regulated in dietary Se supplemented groups compared to non-Se supplemented hens. Moreover, when compared to sodium selenite, only ADS18 bacterial Se showed significantly (p < 0.05) higher mRNA levels in GPX1, GPX4, DIO1, DIO2 and SELW1, while Se-yeast showed significantly (p < 0.05) higher mRNA levels in TXNRD1 than the non-Se group. Conclusions Dietary Se supplementation especially that from a bacterial organic source, improved shell gland and hepatic selenoproteins gene expression in laying hens, indicating that it could be used as a viable alternative source of Se in laying hens. The findings could suggest that organic Se upregulation of shell gland genes and hepatic selenoproteins in laying hens is efficient.

Transcriptome analysis in the shell gland of laying hens affecting eggshell qualities

Background Eggshell plays an important role in protecting against physical damage and microorganic invasion. It is subject to quality loss with increasing hen age, and fragile eggshells result in huge economic losses to the poultry industry. Therefore, improving eggshell quality is particularly important. However, little is known about the potential molecular mechanisms regulating eggshell quality in chickens. Methods In this study, we aimed to compare differential expression of long non-coding RNAs (lncRNAs) and mRNAs between old and young laying hens to identify related candidate genes for chicken shell gland development by the method of high-throughput RNA sequencing (RNA-seq). Results In total, we detected 176 and 383 differentially expressed (DE) lncRNAs and mRNAs, respectively. Moreover, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases revealed that DE-lncRNAs and DE-mRNAs were significantly enriched in “phosphate-containing compound metabolic process”, “mitochondrial proton-transporting ATP synthase complex”, “inorganic anion transport”, and other terms related to eggshell calcification and cuticularization. Through integrated analysis, we found that some important genes such as FGF14, COL25A1, GPX8, and GRXCR1 and their corresponding lncRNAs were expressed differentially between two groups, and the results of quantitative real-time polymerase chain reaction (qPCR) among these genes were also in excellent agreement with the sequencing data. In addition, our research indicates that FGF14, COL25A1, GPX8, and the members of the SLC family may be key genes that affect eggshell quality in hens. Conclusions This study provides a catalog of lncRNAs and mRNAs of the laying hen eggshell gland and will contribute to a fuller understanding of the molecular mechanisms of the function of the shell gland in poultry. Our findings will provide a valuable reference for the development of breeding programs aimed at breeding excellent poultry with high eggshell quality or regulating dietary nutrient levels to improve eggshell quality.