Polymorphisms in the ovoinhibitor gene (<i>OIH)</i> and their association with egg quality of Xinhua E-strain chickens

1. Chicken ovoinhibitor has been reported to prevent contamination and affect storage for eggs. The objective of the present study was to conduct an association analysis between ovoinhibitor gene (OIH) polymorphisms and egg quality traits in the population of Xinhua E-strain chickens and explore its expression characteristics in different tissues. 2. Three single nucleotide polymorphisms (SNPs) were identified and genotyped, in which one synonymous mutation was located in exon16 (G9810A), one in intron7 (A4363G) and one in intron14 (C8937G). The A4363G and C8937G polymorphisms significantly influenced Haugh unit (HU) and albumen height (AH), while HU and AH in AG and CT heterozygous birds were significantly higher than in birds with homozygous genotypes. Diplotype association analysis showed individuals with an H1H4 diplotype had the highest AH and HU values in the investigated population. 3. RT-qPCR results showed that the expression level of the OIH gene was higher in the oviduct and liver than other tissues. During the development of liver at different phases, a drastic decrease occurred during the period of first ovulation event, which suggests the regulation of some unknown factors effected it. 4. Our results indicated that OIH plays a vital role in egg quality. The combinations of A4363G and C8937G might be potential advantageous molecular markers for improving HU of chicken eggs.