Supplemental arginine administered in ovo or in the feed reduces the susceptibility of broilers to pulmonary hypertension syndrome.

1. Two experiments were conducted to determine if in ovo and in-feed arginine (ARG) supplementation is effective in the prevention of pulmonary hypertension syndrome (PHS) in broiler chickens reared at high altitude. 2. In Experiment I, a total of 300 fertile eggs were divided into two equal groups. On d 5 of incubation, one group was injected with 0.5 ml of ARG (20 mg/ml) and the other remained untreated and served as controls. After hatching, male chicks (64 chickens per treatment) were selected and given a commercial maize-soyabean meal diet up to 48 d of age. 3. In Experiment II, a total of 128 male broiler chickens (Ross 308) were randomly assigned to two treatments, a control group that were fed on a basal diet that met ARG requirements and the second was fed on the basal diet supplemented with 1.5 g ARG per kg of diet. 4. Cumulative mortality from ascites was recorded in both experiments. Results from Experiment I indicated that in ovo injection of ARG significantly decreased ascites mortality of broilers (18.8 vs. 43.8%). Results from Experiment II showed a similar effect so that ascites mortality in the group that were given Arg supplement was significantly lower than the control (28.1 vs. 43.8%).