| Reproductive performance is one of the key factors that influences the goat production, which be directly related to the agricultural industry’s output. Litter number is one reproductive performance trait. Placental efficiency (PE) was defined as the ratio of total birth weight to placental weight, the concept was given by Wilson in his research on swine in1999. Many studies on swine, sheep have shown that there was a significantly positive correlation between the litter number and PE. Osteopontin (OPN) gene is one of the major candidate moleculars that affects placental traits. But goat OPN gene polymorphism and its associated with placental efficiency, litter number are rarely reported. Our study is aim to research the genetic diversity of OPN gene and its correlation with PE and the reproductive performance in goat, and provide the theoretical foundation of improving the goat’s fertility.In this study, Dazu black does and Hexi cashmere does are selected as experimental animals. This study was divided into two parts. Fistly, to investigate the correlation of PE, placental traits with reproductive performance in goat. The main methods were as follows:(1) The samples are60and51of Dazu black does and Hexi cashmere does respectively. The data such as does parities, litter weight and litter number were recorded.(2) Placentas were collected immediately after delivery (approximately2h after the birth of the last lamb), the placental traits such as placental weight, cotyledons number and cotyledons weight were measured.(3) The relationships between placental traits and reproduction traits were analyzed. Secondly, to study the relation of OPN gene polymorphism with PE and the reproductive performance in goat.The main methods were as follows:(1) The SNP sites of5’ promoter and exon7of OPN gene were detected by PCR-SSCP methods, respectively.(2) The correlation of the2loci of OPN gene and the placental traits, reproduction traits were analyzed by SPSS16.0for windows. The results are as following:1. The average litter weight, PE and litter number of Dazu black does were4625.87±1687.21g、9.44±1.92and1.97±0.85(n=60). And the average litter weight, PE and litter number of Hexi cashmere does were2314.44±392.13g,8.33±2.20and1.05±0.22(n=51). The litter number was very significantly difference between Dazu black does and Hexi cashmere does (P<0.01),while the PE difference was no significant difference between Dazu black and Hexi cashmere does. It indicated that there is no significant difference on pacental efficiency between Dazu black goat and Hexi cashmere goat. In Dazu black goat, the litter number in group I is significantly higher than those in group II and in groupIII (P<0.05), and there was no significant difference between group II and group III. In Hexi cashmere does, there is no significant difference on litter number among group I, II and III (P>0.05). As a total, the average litter number in group I is significantly higher than those in group II and in groupIII, but there were no significant difference between group Hand groupIII. It indicates that the litter number and litter weight in high PE gourp were both higher than those in low PE group. There is significant positive correlation between pacental efficiency and litter number in goat..2. Only two genotypes, AA and AB were nominated during the area of promoter and the exon7of OPN gene in the Dazu black does and Hexi cashmere does But both mutations on nucleotide sequences did not result amino acid change. Meanwhile, The frequencies of the2loci at the promoter and the exon7of OPN gene were analyzed used χ2-test, and it showed the2loci were with Hardy-Weinbery equilibrium(P>0.05). The association of variations of the promoter and the exon7of OPN gene with plancental traits reproduction traits were analyzed. The results showed that the genotype of OPN gene locus was associated with litter number, with a trend of AA> AB. At the promoter locus, the Dazu black doeswith genotype AA had0.33more litter numbers than those with genotype AB., The Hexi cashmere does with genotype AA had0.08more litter numbers than those with genotype AB. which no significant difference (P>0.05).There was very significantly difference on the Dazu black and Hexi cashmere goat with same genotype in litter numbers (P<0.01).When considering about the placental traits. There was no significant difference on the different spices with different genotype (P>0.05).At the exon7locus, the Dazu black does with genotype AA had0.88more litter numbers than those with genotype AB, there was very significantly difference (P<0.01).The Hexi cashmere does with genotype AA had0.08more litter numbers than those with genotype AB,which no significantly difference (P>0.05),and there was very significantly difference on the different species wihe same genotype on litter numbers (P<0.01). The average litter size of Dazu black goat and Hexi cashmere goat which have the same genotype is significantlly different (P<0.01). The placental efficiency of AB type Dazu black goat and Hexi cashmere goat is significantly different (P<0.01), while AA type has no significant differences (P>0.05), which indicates that the goat OPN gene Exon7allele A is the dominant gene and has significant effects on placental efficiency and litter size, which is a potential molecular genetic marker.The following conclusions are drawn:1. There is significant correlation between pacental efficiency and litter size in the Dazu black goat and Hexi cashmere goat. And there is no significant difference on pacental efficiency between Dazu black does and Hexi cashmere does.2. That exon7of OPN gene has correlation with placental efficiency and reproduction may be a candidate gene that controls high fecundity of the Dazu black does... |
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