The Effect Of Age At Puberty On The Reproductive Performance And Genome-wide Association Study Of Puberty In Yorkshire Sows

Reproductive efficiency has a great impact on the economic benefit of pig production.The main reproductive traits of pigs usually include TNB、NBA、,the number of births,the birth weight,the birth weight of the newborn,the weight of the 21st day,the number of weaned pigs et al.Early puberty sows can save the cost of feeding,increase the number of offspring of female pigs,and increase the utilization rate of sows.Besides,puberty of the sows also determines the mating date which has a very important influence on the reproductive performance and sow longevity and lifetime productivity.In this study,the reproductive performance of sows in early and late puberty was compared,and discussed the optimum age of puberty to solve practical problem and to improve the productivity effect in pig farms.1.In this study,the total number born（TNB）,the number born alive（NBA）,number of healthy piglets（NHP）,litter birth weight（LBW）of American line Yorkshire sows were analyzed and recorded.We divided replacement gilts into 4 groups（≤200d,210²15d,216²30d and>230d）to study the influence for the reproductive performance.The results showed that TNB of late puberty sows were better than the early puberty sows in first parity（P<0.05）and there was no significant difference for other reproductive traits among different puberty groups.Afterwards,we compered and analyzed the effect of puberty with the reproductive performance of second parity,synthesize third and after third parities and all six parities respectively.The results all showed that when puberty age between 201²15 days,the reproductive performance data including TNB,NBA,NHP and LBW were all significant higher than other groups（P<0.05）.To sum up,the reproductive performances of early puberty sows,especially when the puberty age between 201²15 days,were significantly higher than those of the late puberty.This study provides a theoretical basis for the selection of replacement gilts and the application of pig farm production.2.First,the 1×resequencing was performed on 200 yorkshire sows,among this 100 females at the age below 190 days and 100 females at the age above 230 days.The Tassel software 5.2 and Mixed linear model were used to perform a GWAS on the swine puberty trait in 200 Yorkshire population.As a result,3 SNPs were identified to be significantly associated with puberty,distribution on SSC2（P=2.93×10-5）,SSC8(P=3.17×10^-5)and SSC13(P=5.11×10^-5).At last,KDR on chromosome 8 and SLC25A20 on chromosome 13 were identified as candidate genes for the follow-up study on puberty of Yorkshire sows.