Abstract: Feeding experiments were conducted to search after the optimum density and relative effeciency of two kinds of yeast Saccharomyces cerevisiae and S. carlsbergensis and their mixture with alga (Chlorella pyrenoidosa) as the food of rotifer (Brachionus calyciflorus) .The results showed that the optimum density of S. cerevisiae and S. carlsbergensis was 10×10⁶ and 5×10⁶ cells·ml^-1, respectively.The population density and instantaneous growth rate of the rotifer fed with S. cerevisiae and S. carlsbergensis were 40.2 and 26.6%, and 85.5 and 76.6%, respectively of those fed with alga.The feeding effect of yeast-alga mixture in a proper proportion was equal or superior to that of alga.

Key words: Brachionus calyciflorus, Saccharomyces cerevisiae, S. carlsbergensis, Feeding effect, actual farmers’ yield, maize, Northeast China, potential yield, potential farmers’ yield, attainable yield