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The leptin receptor (LEPR) gene is a member of the class I cytokine receptor family, which plays an important role in weight regulation, fat accumulation and neuroendocrine function in animals. This study aimed to explore the association of single nucleotide polymorphisms (SNPs) of the LEPRgene with growth and carcass traits in meat-type quail by PCR amplification and DNA direct sequencing. In this study, genomic DNA was extracted from blood samples of 36 female Savimalt (SV) quails and 49 female French Giant (FG) quails. Growth traits (measured at 3 or 5 wk) and carcass traits (measured at 5 wk) were used for LEPRgene association analysis. The results showed the existence of 9 SNPs (T81C, G90T, C187A, A191G, A219G, G258A, C286T, G346A, and G373A) of the LEPRgene in the 2 quail strains. The statistical analyses indicated that these SNPs of LEPRgene was significantly associated with shank circumference (SC), shank length (SL), breastbone length (BBL), heart rate (HR), and whole net carcass rate (WNCR) of FG (P< 0.05); chest width (CW), body length (BL), leg muscle rate (LMR), whole net carcass rate (WNCR), and heart rate (HR) of SV (P< 0.05). While haplotypes showed significant effect on SL, BBL, heart weight (HW), WNCR, and HR of FG (P< 0.05). Therefore, the LEPRgene may serve as a molecular genetic marker for improving growth and carcass traits in quails.

Insulin-like growth factor 1 receptor (IGF-1R) gene is the main effector of insulin-like growth factor (IGF), which plays an important role in growth, development and reproduction of the animal organism. This study aimed to investigate the association of IGF-1Rgene single nucleotide polymorphisms (SNPs) with egg quality and carcass traits of quail by direct sequencing. In this study, genomic DNA was extracted from quail blood samples of 46 Chinese yellow (CY) quail, 49 Beijing white (BW) quail and 48 Korean (KO) quail strains. Egg quality and carcass traits were measured and used for IGF-1Rgene analysis in 3 quail strains. The results showed that 2 SNPs (A57G and A72T) of the IGF-1Rgene were detected in 3 quail strains. The A57G was significantly associated with yolk width (YWI) in BW strain (P< 0.05). Whereas A72T was significantly associated with egg shell thickness (EST) in BW strain (P< 0.05), and significantly associated with egg weight (EW), egg long (EL), and egg short (ES) in KO strain (P< 0.05). Haplotypes based on 2 SNPs showed significant effect on EST in 3 quail strains (P< 0.05), it also has a significant effect on EW in KO strain (P< 0.05). Meanwhile, A72T was significantly associated with liver weight (LW) and dressing percentage (DP) in 3 strains (P< 0.05). Haplotypes showed significant effect on LW (P< 0.05). Therefore, the IGF-1Rgene may be a molecular genetic marker to improve egg quality and carcass traits in quails.

This study aimed to identify polymorphisms of gonadotropin-releasing hormone (GnRH) gene and their association with growth traits in quail by PCR and direct sequencing. Genomic DNA was extracted from quail blood samples of 36 from Savimalt (SV) and 49 from French Giant (FG). Growth traits were measured and used for candidate gene analysis, as body weight (BW), shank length (SL), chest width (CW), chest depth (CD), breastbone length (BBL), body length (BL), and shank circumference (SC). The results showed that a total of 20 SNPs were detected in GnRHgene, whereas 8 SNPs were significantly associated with growth traits (P< 0.05). The T215C, G279A, C458T, A520G, and C547G were significantly associated with SL at 3 wk of age in the FG strain, whereas A583T was significantly related to BBL and BL, and C591T was significantly related to SL, BBL, and BL, whereas A592G was significantly correlated with SL, CW, CD, BBL, and BL (P< 0.05). The 8 SNPs were significantly related to CW, CD, and BBL at 3 wk of age in the SV strain, whereas A583T, C591T, and A592G were significantly associated with BW (P< 0.05). The G279A showed significant correlations with SL at 5 wk of age in FG, whereas A583T showed significant associations with SC in FG, and C591T was significantly associated with BW and SC in FG, whereas A592T was significantly related to BW, SL, and CD in FG (P< 0.05). The T215C, G279A, C458T, A520G, and C547G were significantly correlated with BW, CW, BBL, and BL at 5 wk of age in SV, whereas A583T, C591T, and A592G were significantly related to BW, SL, CW, BBL, and BL (P< 0.05). Haplotypes based on 8 SNPs showed significant correlation with BW, SL, CW, CD, BBL, BL, and SC in FG (P< 0.05). In conclusion, the GnRHgene could be used as a molecular genetic marker to provide theoretical foundation to improve growth traits in quail.