Study On Candidate Genes Related To High Prolificacy In Southwest Goat

In this study, Polymorphismes of leptin (LEP) gene, leptin receptor (LEPR) gene and Cocaine-Amphetamine-Regulated Transcript (CART) were detected in hundreds of samples of 9 breeds of southwest China including Guizhou white goat, Jintang black goat, Banjiao goat, Chengdu ma goat, Nanjiang huang goat, Gulin ma goat, Matou goat, Dazu black goat and 1 import breed boer goat, through the combinate analysis of polymerase chain reaction and single strand conformation polymorphisms (PCR-SSCP), cloning and sequence analysis. The association between the polymorphism and reproduction traits in goat was also investigated. Results were displayed as follows.In this study, two single nucleotide polymorphisms (A3475G and A3867G) in the 3'flanking region of goat leptin gene were detected and genotyping assays for these SNPs were developed. An assocition study for these SNPs with litter size was performed in an in Guizhou White goat. Statistical analysis demonstrated that the Guizhou White goat does with genotype BB or AB had 0.37 (P<0.05) or 0.18 (P<0.05) kids more than those with genotype AA, respectively. The Guizhou White goat does with genotype BB had 0.19 (P<0.05) kids more than those with genotype AB. These results suggest that A3475G mutation is significantly associated with litter size in goats, and could be useful in selection for increasing litter size in goats.In terms of LEPR6 gen, First of all, three novel SNPs (G2126A, C2972T, and T3188C) were identified through the whole LEPR exon gene. Moreover, fixed effects analysis revealed that goats with genotype AB or EF yielded more kids than those with genotype AA or EE (P<0.05) in Guizhou white breed and Gulin ma breed respectively. Nevertheless, goats in Chuandong white breed displayed no significant difference in litter size. In the trail of birth weight, significant difference only displayed in goats between CC and CD in Chuandong white population (P<0.05). In principle, those results could be valuable in marker-assisted selection programmers for goat breeding. In the CART gene, 10 novel SNPs as well as three microsatellites were detected and mutation at 77 T→C led to an amino acid change (Leu→Ser). In the meantime, the associations between polymorphic loci and reproduction traits were analyzed in Chuandong white, Guizhou white and Gulin ma breeds. Specifically, mutation at the position 524 had no significant effect on the three goat breeds in the trait of litter size. Polymorphism of 539C→A displayed a significant difference in the three breeds (P<0.05) and C7T8/C9T8 of 939 was associated with more litter size (P<0.05) than genotype C₇T₈/C₇T₈ and genotype C₇T₈/C₇T₈. According to the gene variation being analyzed (524C→T, 539C→A and 939CnTn); no obviously association to the birth weight was found. In principle, those findings could be valuable in the marker-assisted selection program for goat breeding.