To improve the growth of genetically improved farmed tila-pia (GIFT), the supplementation of Schizochytrium limacinumand Lactococcus lactis was sequentially optimized by asingle-factor method and central composite design com-bined with response surface methodology (CCD-RSM) usinga developed desirability function (Df) as the response value.The optimum supplementary prescriptions obtained by thesingle-factor method and CCD-RSM were alone 1.5%S. limacinum, alone 1
10 7 CFU/g L. lactis, and 1.22%S. limacinum + 4.01
10 7 CFU/g L. lactis respectively. TheDf of the tilapia fed with the diets supplemented with theseoptimum prescriptions were 0.53, 0.54, and 0.61, respec-tively. The Df, weight gain rate (WGR), and feed conversion rate (FCR) of the tilapia fed with the optimum prescriptionsobtained by CCD-RSM were significantly higher than thoseof the tilapia fed with the diets obtained by single-factorexperiments and the basic diet for 28 days. Furthermore,the results of CCD-RSM can show that there were signifi-cant interactive effects between S. limacinum and L. lactis ontrypsin, α-amylase, lipase, total cholesterol (TC)1 and low-density lipoprotein cholesterol (LDL-C)1 , and Df, but thoseof single-factor method cannot.