Abstract
The present study was conducted to investigate the effect of acute heat stress (HS) of differing temperatures (36, 38 and 40°C) on plasma amino acids concentration of 3-weeks-old broiler birds. Birds were exposed to each temperature and subjected to blood sampling at 0, 30, 60 and 180min after the exposure. Exposure of chickens to 38 and 40°C caused elevation of core temperature compared with their 0min values until those maintained in the 40°C died shortly after 60min post-HS. At all temperatures, concen-trations of plasma Asp, Ser, Tyr and Cys were significantly decreased by the HS compared to their 0min level. On the other hand, plasma Trp and Trp/LNAA were increased in birds kept at 36 and 38°C at 30min post-HS before returning to their 0min concentrations. Changes in some amino acids were clearly temperature-specific. We speculate that changes in plasma Tyr concentration and Trp/LNAA ratio may be related to some of the metabolic responses together with reduced performance observed in HS birds.
