1. Powder residue. Dust is a by-product of flour or vermicelli, such as peas, red beans or potatoes. It contains little crude protein and starch and is of poor quality. Feeding large amounts of powdered residue often causes sows to lose weight, have less milk, and can easily cause sows to lose weight. Long-term feeding can cause sows to produce dead and deformed piglets, and the piglets they produce are stunted and susceptible to skin diseases. Therefore, dregs should not be used to feed sows. If they are fed in small quantities, they must also be combined with protein feed, green feed and calcium. 2. Lees. Although distillers grains contain protein and crude fat, they lack carotene, vitamin D, and calcium, but also contain a certain concentration of alcohol. Therefore, it is not appropriate to feed large numbers of pregnant sows and lactating sows. Otherwise, pregnant pigs can easily cause miscarriage. Or birth stillbirth, weak Aberdeen. 3. Corn, sorghum. Long-term large-scale feeding of sows based on corn and sorghum will cause the sow to reduce her fertility rate, produce stillbirths, weak litters, and even produce hairless piglets. Therefore, when corn and sorghum are used as the basic diet, they should be matched with various feeds containing green feed, wild high quality hay powder, and fish meal containing riboflavin. There is a lack of green feed in winter and spring. Fertilizers such as corn and soybean cake can be fed to the sows after fermentation. In addition, mature feed should be used to feed dry raw materials. At the same time, appropriate amount of feed containing pantothenic acid, such as alfalfa meal, peanut cake, and bran, should be used in the diet. 4. Carbohydrates. The supply of carbohydrates is too much, sows deposit a lot of body fat, so that it is too fat, low libido, not easy to heat, repeated infertility, prone to dystocia, birth stillbirth and fewer calving. Tests have shown that the metabolic energy of sows rises from 25.1 MJ to 29.3 MJ per day and the number of litters decreases by 1.9 heads. 5. Sugar residue. Sugar residue is a by-product of the sugar industry and has a sweet taste, sugar, starch and protein. Can be used to feed growing pigs. However, pregnant sows can not feed sugar residue, because sugar residue contains 55% of potassium salt, the pig's gastrointestinal mucosa has a strong irritant, diarrhea is very strong, easy to cause diarrhea.