The objective of this study was to evaluate if the supplementation of guanidinoacetic acid (GAA) either on top or included with an energy matrix in broiler feed, improves or equalizes the productive and economic parameters in broilers, respectively. The study was carried out in an experimental farm located in the department of Santander-Colombia and lasted 34 days. A total of 1088 Ross 308 AP day-old male chickens, with an initial bodyweight of 42.5 ± 1.05 g, were allotted to four treatments, with eight repetitions of 34 chickens per treatment. The experimental design was completely randomized. The treatments were: T1: Control; T2: Negative control (-80 Kcal); T3: T1 + 600 g GAA on top; T4: T2 + 600 g GAA. The trial comprised three phases, in the pre-starter it was up to a consumption of 250 g/bird, the start up to a consumption of 850 g/bird and the fattening was up to day 35 of age. The following production parameters were determined/calculated: feed intake, bodyweight, feed conversion, European Efficiency Index (EEI) and feed cost for each kg of chicken produced. After verification of the assumptions of homogeneity of the variances (Levene’s test) and normality of the error (Shapiro-Wilk test), the data were subjected to ANOVA analysis of variance, with a significance level of 5%. When significant differences were found (P < 0.05), means were compared using the Tukey test. For data analysis, the statistical program JMP version 15.2 was used. At day 35, the T2 showed 67 g less and 3 FCR points higher than T1 (p< 0.05). When we compared the group supplemented with 600 g / ton of GAA considering an energy matrix of 80 kcal with the control group, we found that the GAA group obtained 21 grams more per chicken, 2 points less in feed conversion, a feed cost per kg of meat produced 2% lower (P < 0.05) and a return on investment (ROI) of 4.46. When we compared the group supplemented with 600 g / ton of GAA on top with the control group, we found that the GAA group obtained 59 grams more per chicken, 4 points less in feed conversion, a feed cost per kg of meat produced 1.1 % lower (P < 0.05) and an ROI of 5.65. In conclusion, the use of GAA both matrixed at 80 kcal and on top, improves the productive and economic efficiency of broilers at 35 days of age.
Key Words: Creatine, Efficiency, Energy matrix, Feed conversion ratio, ROI