L-arginine supplementation of reduced-protein diets improves pulmonary hypertensive response in broiler chickens reared at high altitude.

This study was conducted at high altitude (2100 m above sea level). A total of 208 d-old male broilers (Ross 308) were randomised across 16 floor pens and reared up to 42 d. A normal-protein diet (NPD) was formulated according to the National Research Council. A reduced-protein diet (RPD) was prepared with dietary protein reduced by 30 g/kg relative to that of the NPD. Two additional diets were prepared by adding 2 and 4 g L-arginine (ARG)/kg to the RPD. At the end of trial (42 d), blood sampling was done and carcass characteristics were recorded. ARG supplementation of the RPD at 4 g improved feed:gain in the growing stage and throughout the trial compared with the RPD. The right-to-total ventricular weight ratio was significantly increased in birds fed on RPD compared with those fed on NPD or ARG-supplemented RPD. Feeding RPD caused a significant decrease in plasma concentrations of nitric oxide (NO) and uric acid. Plasma NO level, however, was restored by ARG supplementation of RPD. ARG supplementation of RPD, however, significantly reduced the rate of pulmonary hypertension syndrome mortality compared to the negative control fed on RPD.