The Effects Of Season And Parity On The Reproductive Performance Of Large Yorkshire Sows

The reproductive efficiency of sows is the number of piglets weaned per sow per year,which the most important trait affecting the profits of swine production.Guangdong province is located in subtropical zone,and the climate is high temperature and humidity,which has a severe adverse effect on the reproductive performance of sows.The reproductive performance of the sows changeswith the age of sows.This study used the data of a pig farm in Guangdong province from January1,2013 to 2017 year in December 31,2017.There is a total of 10631 litter records.The relationship between seasons and sow parity with reproductive traits of sows is analyzed.The results are as follows.1.The least square means of the reproductive traits of sows farrowed in separate months were highly significantly different.The least square means of the total number ofpigletsborn farrowed in the months of 6-7 were the lowest,and those farrowed in December the highest,and the difference between them was significant(P<0.05).The number of pigletsborn alive and the number of viable piglets farrowed in December were highly significantly more than those farrowed in the months of 5-10(P<0.01).The litter weightsfarrowed in December were significantly higher than those farrowed in the months of 6-8(P<0.01).The incidences of stillbirths in a littermatefarrowed in January and December were the lowest,highly significantly lower than those farrowed in 5-10 months(P<0.01).The incidences of mummies farrowed in 6-8months were the highest,which were generally significantly higher than those in other months.Seasonal factors have no significant influence on the incidencesof the poorviable piglets in a littermate.2.Parities affected the reproductive traits of sowshighly significantly.The total numbers of piglets born of sows of parities 3-4 were significantly higher than those of sows of parity two and seven and above(P<0.01).The numbers of piglets born alive of sows of parities 3-4 were highly significantly higher than those of sows parity 1-2and seven and above(P<0.01).The numbers of viable piglets of sows of parities 3-4were significantly higher than those of sows parity one and seven(P<0.01).Thelitter weights of sows of parities 3-4 were significantly higher than those of sows of other parities(P<0.05),that of sows of parity one was highly significantly lower than those sows of parities 2-7(P<0.01).The total numbers of piglets born,the numbers of piglets born alive,the numbers of viable piglets,the litter weight and the average weight of piglets born of sows of parities 3-6 were not significantly different.The first parity sows had the highest probability of giving poor viable piglets;the second parity sows had the lowest probability of giving poor viable piglets,the probability was highly significantly smaller than those of the sows of other parities(P<0.01).The first parity sows gave birth to piglets with the highestincidence of stillbirths,and the possibility of second parity sows was lowest;the probability of giving stillbirth piglets of the sows of parity two was highly significantly less than those of sows of parity one and parities 2-7(P<0.01).The results of this study indicateThe results of this study suggest that the sows should be cooled in summer,the number of litters of hot season in the summershould be reduced when the mating plan is made;the reproductive traits of sowsneed to be carefully recorded eliminate old sows with poor reproductive performance.