Factors Affecting The Duration Of Farrowing In Sows And Genetic Parameter Estimation Of Reproductive Traits

In the intensive sow farm,duration of farrowing prolong endangers the health of sows and piglets and causes low sows production efficiency.In this study,We collected data of Large white sow and Landrace sow in a large-scale sow farm in Guangxi province from 2016 to 2017.The least square variance of Duncan test in the R software was used to analyze farms,parities,seasons backfat thicknes and the changes of backfat thicknes effect on duration farrowing of Large white and Landrace sow.The correlation analysis(Spearman)was used to reveal the relationship between the duration of farrowing and reproductive traits.What's more,DMU software was used to compare the variance components of reproductive process and main reproductive traits of sows in different animal models.This study is the first to estimate genetic parameters of the duration farrowing of sows introduced into China and provides a theoretical basis for the breeding of sows.The results were showed as follow:1.The duration of farrowing in sows between breed extremely significant affected(P<0.01);the Landrace extremely significant affected by the pig farms,however,the Large white did not significant affected by the pig farms;the factors of season and parity extremely significant affected the duration of farrowing.2.The back fat thickness in the early pregnancy of the Large white and Landrace extremely significant affected the duration of farrowing;The back fat thickness in the middle and late pregnancy did not significant affected the duration of farrowing of the Landrace,but extremely significant affected the Large white;The change of the back fat thickness in the period of pregnancy significant affected the duration of farrowing of the Landrace,but did not significant affected the Large white.3.The oxytocin did not significant affect the duration of farrowing on both of the Large white and Landrace.4.According to the correlation analysis between the duration of farrowing and the majority of reproductive traits.For the Large white sow,the coefficient correlationbetween the duration of farrowing(DF)and total weight of piglets alive(TLW),total number born(TNB),number of born alive(NBA),number of healthy born(NBH),number of weak born(NBW),number of stillbirths(NBD),mummy number(NBM)and average weight of newborn(ABW)were 0.057,0.178,0.030,0.034,0.035,0.294,0.011 and-0.031,respectively.For the Landrace sow,the coefficient correlation between the duration of farrowing(DF)and TLW,TNB,NBA,NBH,NBW,NBD,NBM and ABW were 0.08,0.23,0.05,0.06,0.33,0.05 and-0.07,respectively.5.Compare the difference between the two models for estimate the variance components of DF,TLW,TNB,NBA and NBD.The results showed that these traits inheritance models should involve in maternal effects.6.According to model 2(involve in maternal effect),the heritability of DF,TLW,TNB,NBA and NBD in the Large white sow were 0.17,0.19 0.16,0.190 and 0.03 respectively.And the heritability of DF,TLW,TNB,NBA and NBD in the Landrace sow were 0.21,0.19,0.18,0.19 and 0.08,respectively.7.The genetic correlation of TNB(0.97)and NBA(0.96)of the Landrace and Large white were the highest.The highest genetic correlation between DF and the majority of reproductive traits of the Large white and Landrace was NBA,0.45and0.67,respectively.