Transcriptome analysis revealed the effect of selenium yeast on improving eggshell quality in aged laying hens

Abstract Background Egg internal and eggshell quality were deteriorated in aging laying hens. Improving egg and shell quality can prolong the laying cycle. Although, selenium yeast (SY) has been found with the potential to enhance the laying performance and egg quality, the underlying mechanisms have not been investigated. Therefore, we investigated the effect and molecule mechanism of selenium yeast on egg and shell quality in aged laying hens. Methods Three hundred 76-week-old Jing Hong laying hens were divided into four equal treatments and fed with Se-deficient diet (SD), 0.15, 0.30, 0.45 mg/kg selenium yeast diet (SY0.15, SY0.30 and SY0.45). At the end of the trial, we evaluated the plasma and tissue selenium content, plasma antioxidant capacity and egg quality. Transcriptomic analysis was performed to investigate the boosting effect of selenium yeast on eggshell quality. The weighted gene co-expression network analysis (WGCNA) analysis was performed to screen out the key candidate genes related with eggshell quality affected by selenium yeast. Results Dietary selenium yeast supplementation enhanced the eggshell strength (SY0.45) ( P < 0.01) and reduced the shell translucence (SY0.15, SY0.30 and SY0.45) to ameliorate the eggshell quality. Moreover, body Se status and plasma antioxidant capacity were significantly enhanced by selenium yeast supplementation ( P < 0.05), and showed a dose-dependent effect. Transcriptomic and WGCNA analysis identified some key candidate genes involved in eggshell quality including cell migration inducing hyaluronidase 1 ( CEMIP ), ovalbumin ( OVAL ), solute carrier family 6 member 17 ( SLC6A17 ), solute carrier family 13 member 5 ( SLC13A5 ), proopiomelanocortin ( POMC ) and proenkephalin ( PENK ). Functional enrichment analysis revealed that selenium may alter the biological process including eggshell mineralization, ion transport and laying period to affect eggshell formation. Conclusion Selenium yeast enhanced eggshell strength and reduced the shell translucence by improving antioxidant capacity, selenium status, and regulating the processes of shell mineralization, ion transport and laying period. These findings provide a novel molecule biomarker for affecting eggshell quality regulated by selenium.