F. Khajali - Department of Animal Science, Faculty of Agriculture, Shahrekord University, Shahrekord, Islamic Republic of Iran.
H. Basoo - Department of Animal Science, Faculty of Agriculture, Shahrekord University, Shahrekord, Islamic Republic of Iran.
M. Faraji - Jihad-e-Agriculture Organization, Shahrekord, Islamic Republic of Iran.

Arginine (Arg) requirements of male broilers (Ross ۳۰۸) reared at high altitude (۲۱۰۰ m above sea level) during the ۱-to ۳-week period was estimated in a graded supplementation method, in which six diets (۲۳۰ g kg-۱ CP and ۳۲۰۰ Kcal ME kg-۱) with Arg increments of ۱.۲۵ g kg-۱ were applied to four pens of fifteen birds each. Dietary Arg content of the experimental groups ranged from ۱۰ g kg-۱ (۸۰% of the NRC recommendation) to ۱۶.۲۵ g kg-۱ (۱۳۰% of the NRC recommendation). Body weight gain, feed: gain ratio, and plasma nitric oxide (NO) concentration were determined as response criteria. Arginine requirements for maximal body weight gain and optimal feed: gain during the ۲۱ days under study were estimated to be ۱۵.۳, and ۱۵.۱ g kg-۱ of diet, respectively. The estimated Arg requirement based on the response in plasma NO was ۱۵.۶ g kg-۱. In conclusion, broilers receiving dietary Arg of ۱۵ g kg-۱ had the best performance. Data obtained for the individual factors are by far the highest values reported for Arg requirements.

Amino acids, Chicken, Growth stage, Needs