Expression Profile of the SCNN1G Gene and Its Association of Polymorphisms With Eggshell Quality Traits in the Potchefstroom Koekoek Chicken Breed.

Enhancement of the production of eggs with good-quality eggshells is of serious interest to ensure food security as eggs are assessed mostly by their eggshell quality. A high rate of cracked eggs has been reported to cause economic loss, increasing the risk of bacterial infections leading to low egg production. Hence, the study was conducted to determine the genetic variation of the Sodium Channel Epithelial 1 Subunit Gamma (SCNN1G) gene in improving eggshell thickness of the Potchefstroom Koekoek chicken breed. The study was conducted at the University of Limpopo with 100 Potchefstroom Koekoek point-of-lay chickens raised intensively. A total of 350 eggs were randomly collected at the 31st to 39th weeks for the collection of internal, external, and eggshell quality traits, and tissues (shell gland, magnum, and isthmus) and blood samples were collected for molecular analysis. Statistical Analysis System Version 9.4 (SAS, 2020) software was used for data analysis. DNA sequencing, general linear model (GLM), and quantitative reverse transcription PCR (RT-qPCR) were used to achieve the objective. DNA sequence analysis revealed two SNPs (A > T at position 2587 and C > T at position 1013 in the coding region). Marker-trait association showed shell thickness (ST) having a significant association (P < 0.05) with all the genotypes where genotype AA was associated with thicker ST than genotype AT; then, genotype CC was associated with thicker ST than genotype CT. The RT-qPCR results demonstrated significant difference (P < 0.05) in SCNN1G mRNA expression levels where the highest expression level was observed in magnum, followed by isthmus and shell gland, respectively. The findings of the study could give evidence on the relevance of genetic markers, mRNA expression analysis, and other molecular biology tools that could be used during genetic selection programs aimed at improving egg production traits specifically eggshell quality.