Effects of Guanidinoacetic Acid and Metabolizable Energy Levels on Performance and Nutrient Metabolism in Broilers

The effects of three metabolizable energy (ME) levels and the use of guanidinoacetic acid (GAA) were evaluated on broiler performance and nutrient digestibility from 1 to 35 d of age. In total, 1944-d-old Ross AP95 male broilers were randomly distributed to six treatments (12 replicates/treatment). Diets were formulated to contain three ME levels (standard energy [SE], -50 kcal/kg reduced energy [-50 RE] and -100 kcal/kg reduced energy [-100 RE]) in all feeding phases with or without GAA inclusion. For the nutrient-metabolizable analysis, 960-day-old male broilers were separately raised in floor pens until 14 d of age and randomly distributed to six treatments (16 replicates/treatment). Data were analyzed with ANOVA and Tukey's test at p ≤ 0.05. There was a significant interaction for the feed conversion ratio (FCR) at 21 days, in which the PC diet showed better FCR when GAA was included. In the evaluation of the main effects, an effect of metabolizable energy (ME) was observed on body condition score (BCS) at 7 and 21 days, feed intake (FI) at 21 and 35 days, and feed conversion ratio (FCR) at 21 days, with the PC diet showing better FCR and lower FI. An effect of GAA was observed on feed conversion ratio at 21 days, with the inclusion of GAA in the diet showing better FCR. In conclusion, broilers fed SE diets with GAA, beyond better performance, had improved AME and AMEn compared to broilers fed RE diets without GAA in starter diets.