PURPOSE: To provide an inexpensive additive, rich in nutritive value and good in digestibility, absorbability and palatability by adding a sugar to a yeast in which the cell wall is enzymically decomposed, adding a yeast thereto, carrying out the alcoholic fermentation, then adding a lactic acid bacterium, performing the lactic acid fermentation and further blending acetic acid therewith.

CONSTITUTION: A sugar such as waste molasses, subjected to the sterilization treatment at 70°C for 20min and having 50% sugar concentration is added to an essence extraction residual yeast after producing a yeast essence as a yeast in which the cell wall is decomposed by the autolysis or adding an enzyme and the resultant mixture is hydrated until the soluble essence content attains 11%. The temperature is then regulated to 32°C and a yeast such as brewer's yeast is added thereto and cultured at 30°C for 60hr while being stirred to carry out the alcoholic fermentation. A lactic acid bacterium such as Lactobacillus acidophilus is added to the resultant culture to perform the lactic acid fermentation or a culture of the lactic acid bacterium is added and acetic acid is further blended therewith. Thereby, the objective additive for fertilizers and feeds, rich in nutritive value, excellent in digestibility, absorbability and palatability and effective in shortening the feed period, improvement, etc., in disease resistance is obtained.