Mutual Relationship between Litter Size and Weaning to First Service Interval in the Sow

Abstract

The present study aimed to investigate the mutual relationship between litter size (LS) and weaning to the first service interval (WSI) in the sow. Retrospective data was collected from 313 farrowings born from 121 Landrace x Yorkshire sows on a farm. The effect of the LS on the subsequent WSI and the effect of the WSI on the subsequent LS were analyzed with one-way ANOVA. Results showed that, on one hand, LS was negatively associated with the WSI. WSI of sows with an LS of 11-13 piglets was longer than that of the sows with an LS of >13, and shorter than that of the sows with an LS of <11. On the other hand, WSI had a quadratic effect on the subsequent LS. Accordingly, sows with a WSI of 6-10 days had a smaller subsequent LS when compared with sows with a WSI shorter than 6 days. When the WSI surpassed 10 days, the subsequent LS tended to increase. The present study indicated that LS and WSI had a mutual relationship. The results suggested that the selection of a large LS may result in a short WSI and the selection of a short WSI may result in a large LS, and both of these will result in an increase in reproductive performance.