Abstract: The anti-nutritional factors are widely distributed in forage plants, which are toxic and hazardous for animals. The toxicity of these natural components may be enhanced when they enter the body of animals by feed intake. The anti-nutritional components from forage and feed can result in reduction of animal products quality and cause severe disease and even death.Here, we introduced the harm of several common anti-nutritional factors, including nitrate, nitrite, glycosides and gossypol in forage and feed of sheep.