| Backfat loss during lactation(BLL)was closely related to reproductive performance.However,the optimal range of BLL has not been definitive,and there is a lack of candidate gene research.Although many studies have shown that the FSHR gene is closely related to reproductive traits,recent studies have shown that the gene has a novel mechanism of regulating animal fat deposition.In view of the fact that the BLL is a phenotypic manifestation of the dynamic balance of fat deposition and catabolism during lactation,it will provide the basis for studying the mechanism of FSHR gene regulation of fat deposition in pigs by exploring the association between this gene polymorphism and sow BLL.Therefore,FSHR can also be used as a candidate gene for sow back loss.In this study,a total of 1178 Large White pigs were used to analyze the differences among BLL groups with 4 reproductive traits.Further,the FSHR gene polymorphisms association with BLL were conducted in the current research.The results are as follows:The sows were divided into 6 groups as <0,0~1,1~2,3~4,5~6,>6 mm based on BLL,and the association analysis of the BLL and reproduction traits was carried out.There was a significant difference in litter size between different groups,among all the times from the first to the sixth parity of the Large White sows(P<0.05).Based on the results of all six parities,there was no significant difference between the fourth,fifth,and sixth group,but they were higher than those of groups 1,2,and 3 significantly.The total number of born(TNB)in 4th group(3~4 mm)was the highest in all groups,reaching 13.54.It was 1.90,2.29,and 1.63 higher than those in groups 1,2,and 3,respectively(P<0.05).Although there were sometimes significant differences in the number of born alive(NBA)and number of heathy born(NHB)between each group,there was no significant difference between the groups in the total analysis of the 6 parities.The range of WEI was 4.79 ~ 4.93 days in each group,and there was no significant difference between the groups regardless of the single or six overall analysis of the parity.The analysis of FSHR gene polymorphism of Large White pig found 9 SNPs in FSHR.Among of the SNPs,4 were missense mutations,which were c.40T>G,c.74C>G,c.1166C>T,c.2006A>G,respectively.The association analysis of the 4 missense mutations with BLL and other correlated traits revealed that,there was a significant association between the c.1166C>T locus and the BLL of the first-born sows.The other three SNPs were not associated with BLL significantly.Besides,there was a significant association between c.1166C>T,c.2006A>G locus and the backfat thickness before delivery of the multiparous sows,but the two locus were not associated with the backfat thickness before delivery of the first-born sows.These four missense mutations were all associated with litter size significantly(P<0.05).In conclusion,about 85% of large white in production BLL focus on 1 to 6 mm.The higher TNB could be obtained by controlling the BLL in the range of 3 to 4 mm.Missense mutation sites c.1166C>T in FSHR gene was associated witn BLL significantly.It was verified that the FSHR gene has the function of regulating the deposition of pig backfat,and can be used as a candidate gene for backfat loss in sows for further research.The results of this study not only provided the basic parameters for controlling backfat of the sow during lactation in production,but also provided potential molecular marker for the control of BLL.It provided technical support and theoretical guidance for improving sow reproductive performance. |
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