The objectives of the present study were to determine the effectiveness of using uniform design in optimizing combination of several growth promoters (betaine, conjugated linoleic acid (CLA), methionine chromium (Met-Cr) and cysteamine (CS)), to examine the potential combined effects among them, using rat as a model animal. The regression function for average daily body gain (ADG) was: Y=5.31511794+5.455582552X_3+0.026494118 685X_4-0.00000007785039453X_1~2-6.83989251 8X_3~2-0.00015110802779X_4~2+0.000022749876 748X_1X_2+0.0000026391823088X_1X_4-0.00049 26339297X_2X_4-0.009843794221X_3X_4 (R=0.994, P=0.052). Where Y: ADG; X_1: dosage of betaine; X_2: dosage of CLA; X_3: dosage of Met-Cr; X_4: dosage of CS. The regression function predicted that when the dosage of betaine, CLA, Met-Cr and CS was 408.2mg/kg, 0mg/g, 0.3mg/g and 80.3mg/kg respectively, the ADG would be the highest as 7.3g/d. The regression function for feed intake: ADG (F:G) was: Y=4.65288580-0.00007884588330X_1-1.36848 93256X_3-0.027621622236X_4+0.00099838070 05X_2~2+0.00012142766692X_4~2+0.0000895401 9195X_1X_3+0.0000014566810120X_1X_4+0.016 628950658X_2X_3+0.03719303306X_3X_4 (R=0.999, P=0.001). Where Y: F:G; X_1: dosage of betaine; X_2: dosage of CLA; X_3: regression function predicted that when the dosage of betaine, CLA, Met-Cr and CS was 44.5mg/kg, 2.5mg/g, 0mg/g and 154.7mg/kg, respectively, the F:G would be the lowest as 3.3. The parameters of the regression function for ADG and F:G were acceptable and the predicted value was near the observed value for ADG and F:G in negative control treatment respectively. Betaine and CS had significantly synergistic action on ADG and F:G. CLA and CS had antagonistic action on ADG. Significantly synergistic action of Met-Cr and CS on F:G was found. Furthermore, low synergistic action of Met-Cr and betaine as well as Met-Cr and CLA on F:G was found. These findings will help future combination of them in obesity prevention and treatment as well as in animal production.
Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of SubtropicalAgricult Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of SubtropicalAgricult Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agricul Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of SubtropicalAgricult