Breeding herds should have a defined sow elimination method, and the proportion of sows in each parity should be kept stable. The ideal ratio of 1-8 parity sows should be approximately 17%, 16%, 15%, and 14%, respectively. 13%, 11%, 10%, and less than 4%. If there are enough unbred gilts, several general principles must be followed to decide whether to eliminate certain sows at weaning. First of all, we must eliminate two consecutive sows with fewer births, but the first-time sows are too lightly weighted, excessive feeding during pregnancy, excessive weight loss during lactation, and poorly weaned boars should not be included. Secondly, we should eliminate sows that are not estrus when they are even treated with hormones. Sows should be observed up to 18 days after weaning and 7 days after hormone treatment. If these sows do not fit into the next estrus period, they should be eliminated because the sows' slaughter rate is generally less than 50%. Again, it is necessary to eliminate the sows that have already produced 6-7 litters, because the problems that have started to appear are usually: the number of litters born to be litter is small (mainly due to an increase in the number of stillbirths), the size of the piglets is uneven, and the weaker piglets are easier Fear of cold, more cases of breast, body awkward, easy to crushed piglets and so on. In order to reduce the problem of movement disorders, attention should be paid to the condition of the extremities when selecting or buying sows, using high-quality flooring in the pens and not raising the weight of the sows. However, despite the fact that limb and foot disease sometimes occurs, sows are suffering from health problems. Poor conditions, such as infectious vaginitis, will inevitably be eliminated. Http:// Qingzhou JuLong Agriculture Equipment Co.,Ltd , https://www.julonggrowtech.com