Growth Performance and Right Ventricular Hypertrophy Responses of Broiler Chickens to Guanidinoacetic Acid Supplementation under Hypobaric Hypoxia

Guanidinoacetic acid (GAA) has been shown to spare arginine (ARG) requirements in chickens. ARG plays a critical role in enhancing growth and preventing right ventricular hypertrophy (RVH) in broiler chickens subjected to hypobaric hypoxia. However, ARG is not available as a feed grade supplement in the market. Therefore, we evaluated the effects of commercially available GAA supplement as an alternative on growth performance and RVH in broilers raised at high altitude (2100 m). Five graded levels of GAA ranging from 0 (control) to 2 g/kg were provided in isoenergetic and isonitrogenous diets to broilers (Ross 308) from day 1 to 42, post-hatch. Results indicated that responses to GAA were nonlinear and attained plateau values within the studied range of GAA supply. While weight gain and feed intake were unaffected by GAA supply, feed conversion ratio was improved by GAA supplementation up to 1.5 g/kg. Similar trends were observed for the proportions in the liver and heart, as well as hematocrit. GAA supplementation at 1 and 1.5 g/kg resulted in reduced abdominal fat deposition as well as a decline in right-tototal ventricular weight ratio (RV:TV, an index of RVH). A significant (P<0.05) increase in serum nitric oxide concentration was observed at 1 and 1.5 g/kg GAA supplementation. However, GAA supply led to lower serum malondialdehyde and uric acid levels than in the control. In conclusion, GAA supplementation up to 1.5 g/kg had the potential to improve growth performance and RVH response. Meanwhile, GAA supply beyond 1.5 g/kg could deteriorate these responses.