In order to ensure the growth of beef production, it is necessary to rationally use all available reserves and, fi rst of all, the allocation of intra-breed types and lines that ensure the improvement of herds and breeds of animals with high genetic potential under specifi c natural conditions. Therefore when breeding cattle of dual purposes breeds important role should be attached to the selection of animals of diff erent lines, body types, related groups that provide high fattening, and beef indicators with good adaptive traits. In relation with the above, it has been considered relevant to study the formation of beef productivity of steers of diff erent exterior and constitutional intra-breed types of Simmental breed with the determination of the energy and biological value of products under intensive rearing. As well as the infl uence of feeding conditions and maintenance of young animals of Simmental breed, taking into account the exterior and constitutional type, on the formation of live weight in the postnatal period, with a comparative assessment of the growth intensity depending on the body type. As a result of the research, the association between the live weight and the weight of the most active internal organs: heart, lungs, kidneys, which characterize the level and nature of metabolic processes that have a positive eff ect on the formation of beef productivity of experimental Simmental steers of domestic selection depending on the exterior and constitutional types. It has been found that to increase the production of high-quality beef, it is advisable to intensively rear Simmental steers of medium and compact types up to 18 months of age with a live weight of 460,2–517,8 kg, a carcass weight of 252,3–282,4 kg, a slaughter yield of 58,1–59,4 % and expenditures of feed of 3,7–4,0 thousand tons of EFU per 1 head.
