Production method of compound amino acid feed additive rich in gamma-aminobutyric acid (GABA)

The invention discloses a production method of a compound amino acid feed additive rich in gamma-aminobutyric acid(GABA), which comprises the following steps: concentrating mixed amino acid mother liquor, which serves as a raw material and is obtained from the hydroxylation production of L-cystine or extraction of other monomer amino acids, under reduced pressure, filtering concentrate, diluting filtrate with water, decolorizing with active carbon, adjusting pH value to 5 to 7 with acid or alkali, adding glutamate decarboxylase in an amount which is 5 to 10 percent of the volume of the motherliquor obtained after pH adjustment and a phosphopyridoxal added coenzyme factor in an amount which is 0.05 to 0.1 weight percent, fermenting at constant temperature for 15 to 20 hours, concentratingunder reduced pressure or with an RO reverse osmosis membrane, and spray drying to obtain the compound amino acid feed additive rich in GABA. The method has the advantages that: the problem of low GABA yield and high productio