The research paper presents the results of the use of a new probiotic feed additive containing a dry culture of lactic acid bacteria and fillers of plant origin in the diet of young poultry. The use of probiotics in the diet of broiler chickens showed that outdoor and cage keeping conditions did not significantly affect the economic and productive parameters of poultry, while the use of feed additives in their diet provided an increase in the preservation of Ross 308 cross by 6.0 and 4.0%, the live weight gain by 5.6 and 5.5%, and the slaughter yield of gutted chicken carcasses by 3.2 and 4.0%, as well as the decrease in the feed conversion by 4.4 and 3.9%. In broiler chickens of the Cobb 500 cross, the feed additive provided an increase in the preservation of livestock by 4.0 and 6.0%, the increase in the live weight by 6.6%, the slaughter yield of the gutted poultry carcass by 2.1 and 2.7%, as well as the decrease in feed conversion by 5.9 and 5.4%. As a result of the research, it is recommended to introduce a new microbial feed additive in the diet at a dose of 0.7 kg per 1 ton of feed additionally throughout the entire growing period to improve the preservation, increase the live weight of poultry, meat productivity and its quality, and reduce the cost of compound feed to obtain a unit of production for broiler chickens of Ross 308 and Cobb 500 crosses.