Litter Size In Pigs Molecular Markers And Their Effect

Two important methods to identify markers of QTLs(quantitative traits loci) are genome scan and the candidate gene approach. in this study the Estrogen Receptor, Prolactin Receptor, Ryanodine Receptor, Follicle Stimulating Hormone Receptor as candidate genes and nine microsatellites on chromosome 8 were investigated for genetic markers of lifter size in pigs. 1. Three new genetic molecular markers of litter size in pigs were primarily confirmed: ESRB in Exon 8 of Estrogen Receptor gene, FSHRB in Exon 7 of Follicle Stimulating Hormone Receptor gene and microsatellite SWR1 101 on chromosome 8. 2. Effective genetic molecular markers were selected: advantageous and disadvantageous genetic markers of litter size in pig were determined after comparing several genetic molecular makers. Advantageous genetic molecular markers which could increase litter size and no negative effect on pig growth. including the genotype BB on the loci of ESR.% FSHRB and RYR1 and the genotype AA on the loci of ESRB and PRLR. There were five disadvantageous genetic markers that had disadvantageous effect on reproductive ability of sows. They were genotype AA on the loci of ESR~ FSHRB , BB on the loci of PRLR, ESRB and BD of microsatellite SWRI 101. 3. Genetic molecular markers of litter size in pigs could not adversely affect growth traits: About 17000 piglets were analyzed to determined whether genetic molecular markers influenced birth weight and weaning weight, no significant effect was fonud. 4.The traditional idea was verified from molecular genetics and anatomy that the sows with big ovum and uterus could get more total number bom(TNB) and number born alive(NBA): 103 F2 mature sows of a reference family (Large white X Meishan) were slaughtered and sow's weight of two ova~ uterus, volumn of uterus, the length of oviduct and womb horn were measured, meanwhile, 145 the relationships between the size of ovum and womb litter size and polymorphisms of genes were analyzed. The results show that The sows?size of ova and uterus were also bigger if sows carried the favorable lifter size gene, It also proved it was possible and reasonable for genetic molecular markers of litter size to be applied as markers. 5.Two fast effective1 simple new methods for investigating two genetic markers at the same time were developed, the two genetic markers (RYR1SL RYR1SRB) could be detected by PCR-RFLPs at the same time, it could not only reduce cost ,but also increase accuracy and reliability. 6. Genetic molecular markers of litter size were verified and applied in pigs production. Genetic markers were used to analyze total number bom(TNB) and number born alive(NBA) in sows of Landrace X Large white, The results were quite similar with those obtained conclusion of Large White and Erhualian. These markers could be used in marker assisted selection for litter size in pigs. 7. Allele frequencies, Heterozygote and polymorphism information content of nine Microsatellites (SW205 S0086 SW790 SW268 SW905 SWR11OU. SW444 SW1O7O OPN) on chromosome 8 were significantly different in these of ErhualianL, Large white, Landrace X Large white and reference family F2 sows. 8. No polymorphism in PRLR1 and FSHRA loci was found by PCR-SSCP. but polymorphisms of ESR ESRBI ESRA RYR1 PRLR and FSHRB were found by PCR-RFLPs, Allele...