(1) There are many causes of coccidia infection in small intestine. It is not a single coccidia infection, but one of the main causes. As we all know, coccidia exist everywhere where chickens are raised. Due to the different environmental conditions, management level and drug control level, coccidia are more common in broilers aged 30-40 days, mainly because coccidia have completed their life cycle many times in chickens and in the environment, and the number of oocysts in feed and feces has increased significantly, which leads to serious coccidiosis infection at this stage, especially Eimeria maxima, Eimeria maxima and Eimeria poisoning. Because coccidia grow and multiply in the intestinal mucosa, the intestinal mucosa thickens, falls off seriously and bleeds, which makes the feed almost indigestible. At the same time, the absorption of water is also obviously reduced. Although chickens drink a lot of water, it will also cause dehydration, which is one of the reasons why the feces of broilers become thinner and the feed in the feces is undigested. (2) Changes of intestinal environment During the infection of coccidia in small intestine, coccidia in small intestine rapidly divided and propagated in intestinal mucosal cells. Because the proliferation of coccidia needs to consume a lot of oxygen in the host cells, the intestinal mucosa produces a lot of lactic acid, which seriously reduces the pH value in the intestinal cavity of broilers. Due to the change of intestinal pH value, intestinal flora changes, beneficial bacteria decrease and harmful bacteria multiply, especially Escherichia coli, Salmonella and Clostridium perfringens. The pH value of intestinal contents decreases, which reduces the digestion ability of various digestive enzymes and leads to indigestion of feed. In addition, stimulating intestinal mucosa will accelerate intestinal peristalsis, increase the discharge of digestive juice, and shorten the time for feed to pass through the digestive tract, which will lead to feed indigestion and "overeating". Due to the acceleration and strengthening of intestinal peristalsis, bile secreted by gallbladder is quickly discharged from the intestine and mixed with undigested feed, forming the characteristic feces of the syndrome-slightly yellow feces. (3) Long-term use of antibiotics Due to the prevention and treatment of intestinal diseases, long-term use of antibiotics in large quantities not only kills harmful bacteria, but also kills beneficial bacteria, resulting in flora imbalance. This situation is often difficult to cure, and there are many cases caused by this reason. In this case, some western medicine was used to treat the drug, and the situation was slightly better, and it recurred after stopping the drug. Therefore, in view of this situation, it is best to add 0.5% probiotics for long-term feeding and adjust the balance of flora, such as repairing intestinal mucosa with better cod liver oil and treating intestinal tract with traditional Chinese medicine. (4) Viral diseases have some intractable diarrhea, which is difficult to cure with antibiotics alone. Therefore, we should consider whether it is atypical Newcastle disease or mild avian influenza, and treat it according to the anatomical situation. (5) The reason for feed is the use of moldy feed raw materials and excessive addition of miscellaneous meal. (6) Long-term use of antibiotics to treat loose stool caused by renal edema, or sulfonamides to treat renal edema caused by coccidia and other diseases. At this time, it is necessary to use some kidney-protecting and kidney-expelling drugs combined with vitamin C+ glucose+oral rehydration salts. (7) Self-poisoning In the course of onset, a large number of intestinal epithelial cells rupture, decompose and rot under the action of bacteria, and a large number of toxic substances produced by the death and disintegration of worms are absorbed by the body and then self-poisoned, leading to clinical cases of first excitement, then collapse, coma and failure. (8) Measuring the phenomenon of dyspepsia is not simple, but comprehensive. First of all, we should provide high-quality, complete and balanced feed, improve feeding management, maintain temperature balance, adjust with the growth age of broilers, and do not change the padding frequently. Conventional preventive drugs to control coccidia, Clostridium welchii and glandular gastritis. Astragalus polysaccharides and high-quality vitamins are used to improve immunity.