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ABSTRACT In this study, we evaluated how guanidinoacetic acid (GAA) addition in diets with various metabolizable energy (ME) contents affects the performance of broiler chickens. We also estimated the equivalence of GAA in ME. We distributed 1,280 one-day-old broilers in a completely randomized design with eight treatments, eight replicates, and twenty birds per experimental unit. Treatments were based on ME levels (2,775-2,875-2,975 kcal/kg; 2,850-2,950-3,050 kcal/kg; 2,925-3,025-3,125 kcal/kg; or 3,000-3,100-3,200 kcal/kg, from 1 to 7, 8 to 21, and 22 to 42 days of age) and the inclusion of GAA (0 or 600 mg/kg). Supplementation of GAA increased weight gain in broilers at an energy level of 2,908 kcal/kg and improved feed conversion ratio (FCR) at energy levels of 2,908 and 2,983 kcal/kg. There was a linear reduction in feed intake and an improvement in FCR of broilers with increasing levels of energy in diets, with and without GAA addition. Solving the equivalence equation, by applying each of the weighted average energy levels studied. indicates the GAA equivalence of 133, 103, 74, and 44 kcal/kg of diet. In conclusion, GAA supplementation improves broilers’ efficiency of energy use; the average ME equivalence of 600 mg/kg of GAA is 88.5 kcal/kg. study (GAA (ME chickens 1280 280 1,28 onedayold one day old treatments replicates unit 2,7752,8752,975 277528752975 2,775 2,875 2,975 2 775 875 975 (2,775-2,875-2,97 kcalkg kcal kg 2,8502,9503,050 285029503050 2,850 2,950 3,050 850 950 3 050 2,850-2,950-3,05 2,9253,0253,125 292530253125 2,925 3,025 3,125 925 025 125 2,925-3,025-3,12 3,0003,1003,200 300031003200 3,000 3,100 3,200 000 100 200 3,000-3,100-3,20 7 21 4 age 0 ( 60 mg/kg. mgkg . mg mg/kg) 2908 908 2,90 (FCR 2983 983 2,98 equation studied 133 103 74 diet conclusion use 885 88 5 88. 128 28 1,2 7752 8752 2,7752,8752,97 27752875297 2775 2,77 2875 2,87 2975 2,97 77 87 97 (2,775-2,875-2,9 8502 9503 2,8502,9503,05 28502950305 2850 2,85 2950 2,95 3050 3,05 85 95 05 2,850-2,950-3,0 9253 0253 2,9253,0253,12 29253025312 2925 2,92 3025 3,02 3125 3,12 92 02 12 2,925-3,025-3,1 0003 1003 3,0003,1003,20 30003100320 3000 3,00 3100 3,10 3200 3,20 00 10 20 3,000-3,100-3,2 6 290 90 2,9 298 98 13 1, 2,7752,8752,9 2775287529 277 2,7 287 2,8 297 9 (2,775-2,875-2, 2,8502,9503,0 2850295030 285 295 305 3,0 2,850-2,950-3, 2,9253,0253,1 2925302531 292 302 312 3,1 2,925-3,025-3, 3,0003,1003,2 3000310032 300 310 320 3,2 3,000-3,100-3, 29 2, 2,7752,8752, 277528752 27 (2,775-2,875-2 2,8502,9503, 285029503 30 3, 2,850-2,950-3 2,9253,0253, 292530253 31 2,925-3,025-3 3,0003,1003, 300031003 32 3,000-3,100-3 2,7752,8752 27752875 (2,775-2,875- 2,8502,9503 28502950 2,850-2,950- 2,9253,0253 29253025 2,925-3,025- 3,0003,1003 30003100 3,000-3,100- 2,7752,875 2775287 (2,775-2,875 2,8502,950 2850295 2,850-2,950 2,9253,025 2925302 2,925-3,025 3,0003,100 3000310 3,000-3,100 2,7752,87 277528 (2,775-2,87 2,8502,95 285029 2,850-2,95 2,9253,02 292530 2,925-3,02 3,0003,10 300031 3,000-3,10 2,7752,8 27752 (2,775-2,8 2,8502,9 28502 2,850-2,9 2,9253,0 29253 2,925-3,0 3,0003,1 30003 3,000-3,1 2,7752, (2,775-2, 2,8502, 2,850-2, 2,9253, 2,925-3, 3,0003, 3,000-3, 2,7752 (2,775-2 2,8502 2,850-2 2,9253 2,925-3 3,0003 3,000-3 (2,775- 2,850- 2,925- 3,000- (2,775 (2,77 (2,7 (2, (2