1, from the nutritional quality of protein array, captive broiler chickens, captive hens and grass chickens, followed by increasing, while the nutritional quality of fat is the opposite, followed by decreasing. 2. The differences in the nutritional quality of protein and fat between the three chickens are closely related to their feed environment and conditions. 3. The nutritional quality of vitamins in grass chickens is generally higher than that of captive chickens, which is mainly due to the low fat content of grass chickens. From the comparison of nutritional quality index requirements, only the nutritional quality of niacin and vitamin E meets the requirements. Therefore, compared with other chickens in captivity, grass chickens have little advantage in the nutritional quality of vitamins. 4, the nutritional quality of minerals, grass chickens higher than chickens, the main reason is because the grass contains low fat. However, the nutritional quality of magnesium, iron and selenium is significant in grass chickens, which may have a certain relationship with feeding methods. 5. In general, if it is possible to solve the safety problem of grass chicken feed, the grass chickens produced in a free-range manner are the future directions for the production of broiler chickens and laying hens. Dental Impression Tray Series,Dental Impression Material,Dental Moulding Powder,Alginate Impression Moulding Powder Ningbo Carest Medical Instrument Co.,ltd , https://www.carestmed.com