Genome-wide Association Study Of Important Economic Traits And Comparative Study On The Accuracy Of Genome Selection In Large Yorkshire Pigs

The pig industry has always been an important field of animal husbandry in China.Excellent pig breeds are the basis for improving pig productivity.Traditional breeding methods can no longer meet the current needs.With the completion of complete genome sequencing of livestock and the rapid development of molecular breeding technology,genome-wide association study(GWAS)for important economic traits of pigs has become a reality,Genomic selection(GS)has the advantages of high accuracy in estimating breeding values and reducing costs,and can be used for early selection in breeding pigs.This study collected phenotypic data such as daily feed intake,corrected body weight and age of 100 kg,and corrected backfat thickness from 100 large white pigs,and conducted correlation analysis on their feeding behavior and growth traits.The "Zhongxin No.1" chip was used for SNP genotyping of experimental pigs and genome-wide association study of important economic traits.By combining the genotype data obtained from chip detection and relevant data in the Dekang database,the accuracy of whole genome selection was verified for the corrected 100 kg body weight,age,eye muscle thickness,total litter size,and live litter size traits in large white pigs.The research results are as follows:(1)foraging behavior concentrated at 7:00-10:00 and 14:00-20:00,foraging competition was the most intense at 15:00,foraging behavior was more active during the day than at night,and in the afternoon than in the morning,the daily intake and rate of food intake increased gradually,the duration and times of food intake decreased gradually The results showed that the breeding pigs with low feed-weight ratio,thin backfat and short dayage of 100 kg body weight could be selected according to the feeding characteristics of high daily gain,low daily feed intake,long average single feed intake,low daily feed intake and short daily feed intake.(2)the results showed that the initial weight of breeding pigs could be increased to 40-60 kg,and the determination time could be shortened while ensuring the accuracy,thus,the utilization ratio of the production performance measurement system can be improved.(3)the results showed that MMADHC and ENSSSCG0000050050 were associated with daily gain and backfat thickness in chromosome 15,and they could be used as candidate genes affecting daily gain and backfat thickness in large white pigs;LEXM and TTC22 in chromosome 6 were significantly associated with birth weight at genome level and could be used as candidate genes for birth weight traits FAM83 G,ZNF827,HNF4 A,CHEK1 and SSBP2 may have potential effects on daily weight gain,age at target body weight,feeding duration and daily food intake by regulating the initiation of transcription of Class II gene promoters.(4)The heritability of corrected 100 kg body weight day age,corrected eye muscle thickness,total litter size,and live litter size assessed in this study were 0.23,0.13,0.06,and0.04,respectively.The results showed that the ss GBLUP model had higher prediction accuracy than the ABLUP model under the 5x and 10 x cross validation strategies for these four traits,and the deviation from the true value was smaller.Moreover,increasing the number of reference groups could improve the accuracy of whole genome selection.