The new mixed feed for chickens fattening containing wheat, maize, soybean meal, wheat bran, rapeseed oil, minerals, amino acids, vitamins, hempseed and flaxseed increases the live weight of chickens at the end of fattening, content of γ-tocopherol and n-3 polyunsaturated fatty acids in the breast muscle and tibia strength of chickens and reduces the ratio of n-6/n-3 polyunsaturated fatty acids in meat. Feeding this mixed feed thus leads not only to an improvement in the performance and quality of bones, which indicates an increase in the living conditions of breeding, but also to an increase in the deposition of substances important from the point of view of human health and to an extension of the stability and thus the shelf life of the products.