Effect of dietary L-tryptophan supplementation and‏ ‏light-emitting diodes on growth ‎and immune response of broilers

Lightemitting diodes (LEDs) lights are more energyefficient and provide adequate illumination compared to compact fluorescent (CFL) lamps and incandescent light (ICD) bulbs. However, as new light sources, the LED lights may have a stress effect on broiler chickens. Thus, this study aimed to determine the effects of dietary Ltryptophan (Trp), as an antistress agent and different color temperatures of lightemitting diodes on immune responses and growth performance of male broiler chickens. Four hundred and eighty dayold Ross 308 male chicks were used from day 1 to 42. The chicks were randomly distributed into six treatment groups in a 2 × 3 factorial arrangement [0 or 1 g Trp per kg diet along with neutralwhite (4286 K), warmwhite (2990 K), and incandescent (2790 K) light bulbs] with four replicates of 20 chicks each. Results showed that dietary Trp and Trp×light interaction did not affect growth performance, immune responses, a total number of leukocytes, and different leukocytes count (heterophil, eosinophil, monocyte, and lymphocyte) of male broiler chickens. However, LEDs’ different color temperatures significantly affected the feed conversion ratio (FCR) and primary antibody of sheep red blood cell (SRBC). The FCR was the lowest in the warmwhite light, and primary SRBC antibody titers of the chicks were the highest. In conclusion, although adding Trp to male broiler diets did not affect the growth performance and immune responses of chickens, the warmwhite light improved the FCR and primary SRBC.