Abstract：Osteopontin (OPN) is a secreted phosphoprotein, playing important roles in eggshell formation. In order to analyze the correlation between the single nucleotide polymorphism (SNPs) of OPN and egg-quality traits of laying duck, the SNPs in the exon 7 of OPN gene were screened by PCR product sequencing in 100 Shanma laying duck and 100 Shaoxing laying duck (Anas platyrhyncha domestic). Eight SNPs in Shanma laying duck and 9 in Shaoxing laying duck were detected. The effects of G544C, A671G, G672C,T761C and T873C on some egg-quality traits of Shanma laying duck reached significant or highly significant difference levels. And the effects of A671G, G672C and T761C on some egg-quality traits of Shaoxing laying duck reached significant or highly significant difference levels. For the Shanma laying duck, 3 genotypes in A671G, G672C, T761C, and T873C SNP sites were detected. Genotype BB of the sites A671G and G672C was significantly superior to the other two genotypes in 300-day-old's eggshell thickness (P＜0.01), while AA genotype was significantly higher in 300-day-old's Haugh unit (P＜0.05). BB genotype of the T761C site was significantly higher than the other two genotypes in 300-day-old's eggshell thickness (P＜0.01). BB genotype of the T873C site was significantly higher in 300-day-old's eggshell thickness and eggshell strength (P＜0.05) and 500-day-old's eggshell thickness, eggshell strength and eggshell weight (P＜0.05). Thus, we deduced that the allele B of T761C and allele B of T873C were effective genes to egg-quality trait. For the Shaoxing laying duck, AA genotype of the T761C site was significantly lower than the other two genotypes in 300-day-old's eggshell thickness and eggshell strength (P＜0.05), while BB genotype was significantly lower than AA and AB in 500-day-old's egg shape index, egg weight, eggshell weight and weight of egg contents. The results indicate that OPN gene can be used as a molecular marker for egg-quality traits in MAS breeding of laying duck.
