Supplemental L-arginine Modulates Developmental Pulmonary Hypertension in Broiler Chickens Fed Reduced-Protein Diets and Reared at High Altitude

This experiment was conducted to evaluate the effects of supplemental L-arginine (ARG) in reduced-protein diets on cardiopulmonary performance and intestinal morphology in the broilers reared at high altitude. A total of 156 day-old male broilers were randomly assigned to 3 treatments and 4 replicates of 13 chicks and reared up to 42 days of age. Treatment groups were designed as a normal-protein diet (NPD), a reduced-protein diet (RPD) with 30 g/Kg less crude protein compared to the NPD, and a reduced-protein diet plus 4 g/Kg L-arginine (RPD + ARG). There were no significant differences among dietary treatments for intestinal morphology and weight gain. Feed conversion ratio was improved in the chickens fed RPD + ARG compared to those fed RPD alone. The right to total ventricular weight ratio (RV:TV) was significantly increased in the chickens fed RPD when compared to those fed NPD or RPD + ARG. Serum nitric oxide and amplitude of the S waves of electrocardiogram significantly declined by reducing dietary protein content. Relative expression of endothelin-1 (ET-1) gene was higher in the heart and lungs of chicks fed RPD than those fed NPD and it was off set when ARG supplemented to RPD (P). In conclusion, supplementing reduced-protein diets with ARG would be an effective strategy to prevent the development of pulmonary hypertension by increase in nitric oxide, and decrease in RV:TV and ET-1 gene expression.