Study On The Relationship Between The Reproductive Performance And Backfat Thickness Of The Pregnant Large White Sows

This paper was studied the effects of backfat thickness in Large White sows which after be mated between with litter weight, total number born, number born alive.421 Large White sows were selected and measured the backfat thickness in the pregnant stages of early, middle and the later. After that, the sows' reproduction traits, such as litter weight, total number born, number born alive were traced and recorded to analysis.The results showed that the sows' pregnant backfat thickness increased with the increasing of pregnant time. By the analysis of variance of backfat thickness and reproductive performance, it showed that the difference between the backfat thickness and the reproductive performance was not significant (P>0.05), through the analysis of relationship between backfat thick and reproductive performance, we could see that the backfat thickness and litter weight was positively correlated, and the total number born and the number born alive is negative correlation between them, but no significant correlation (P>0.05).At the same time, we were tracked backfat thickness measurement with once a month from the sows mated for 107 Large White pregnant sows of Zhenghong, because a part of the sows return to estrus and die, etc. finally, we had 52 pregnant sows that complete 5 times backfat thickness determination, we could find that when a sow was pregnant from 60d to 90d,the growth rate of its backfat thickness is the fastest than others, and the difference was significant (P<0.05),it shows that the nutritional requirement of the pregnant sows at the time is relatively large. So, management should be careful of strengthening nutrition supply at this stage of gestation sow in production process, and protecting nutritional requirements of sows. This issue is also researched for Large White sows backfat thickness lost in the lactation and the next reproduction performance. According to the loss of sows' backfat thickness in it's lactation, sows were divided into three groups, which is low(<3mm), medium(3-6mm), high(>6mm). we could find that the high groups(>6mm) is significantly worse than the other two groups, of which is the next litter weight, total number born, number born alive and death and culling rate of sows. But the differences between the other two groups were not significantly. It showed that if the loss of sows' backfat thickness in the lactation is serious, it will seriously affect the reproduction performance of its next pregnancy; otherwise, it will hardly affect the reproduction performance under the conditions of that to strengthen the nursing of sows in the next pregnancy.