The new compound microecological preparation was made of two strains of bacillus and laclobacillus isolated and selected in our laboratory. Results of a series of test on animals showed that when the preparation was used as feed additive to raise young animals, body weight gain, feed efficiency, digestibility and metabolic energy of broilers and piglets were increased compared with that of control groups. In addition, effective prevention of dysentery disease of broilers has also been found. Our data presented here and published earlier suggested that the microecological preparation is a valuable feed additive for animals in the near future.