Increasing the value of diets for farm animals market offers a wide range of feed additives, biostimulants, of domestic and foreign production. In this regard, the study of efficiency of use of the microalgae strain Chlorella vulgaris IFR number C-111 in the diets of pigs has important scientific and practical value. The aim of this work was to study the potential for increasing reproductive functions of breeding boars at the expense of introduction in their ration of a suspension of Chlorella. For the experiment 5 groups of breeding boars of Landrace breed (3 animals in each, at the age of 2,5-3 years) were selected on the principle of analogy. The study was carried out in two periods (preparatory, lasting 40 days and experienced, lasting 60 days). In the preparatory period, the grunts all experimental groups received feed from К-57-2 to 3,5 pounds a day. In the experimental period, boars of the first control group were fed the same way as in the preparatory period, and for the grunts of the second, third, fourth, fifth groups in the daily diet a suspension of Chlorella in an amount of 1, 3, 5, 7 ml per 1 kg of live weight was added. The studies found that feeding boars-producers with a suspension of Chlorella in an amount of 1; 3; 5; 7 ml per 1 kilogram of live weight was allowed to increase sperm volume by 4,3; 15,4; 30,7; 30,9 %, the concentration of sperm in 1 ml of semen 5,3; 13,6; 36,7; 28,1 % of the total number of sperm in ejaculates 9,9; 31,3; 78,8; 67,9 %>, the mobility of sperm cells by 1,2 4,9; 7,5; 7,5 %>, the resistance of sperm 5,7; 11,9; 37,9; 32,5 %, suffers sperm outside the body 5,4; 12,6; 24,1; 23.8 % compared with the preparatory period. Studies have shown that for all tested variants on the economic valuation of the data received in the experiments the optimal dose of introduction in the rations of breeding boars suspension of Chlorella should be considered: 5 ml per 1 kg of live weight a day.