Impact of dietary supplementation of unsaturated and saturated fatty acids on bone strength, fatty acids profile of thigh muscle and immune responses in broiler chickens under heat stress.

Background: There have been some reports that supplementation of fat could alleviate the negative effects of heat stress on performance in broilers. However, information regarding compensation for the adverse effects of heat stress with diets differing in fatty acids source on immune system, bone strength and carcass quality of heat‐distressed broilers is limited. Objectives: The objective of this study was to investigate the effects of diets differing in fat source on performance, immune system, bone strength, and carcass quality of heat‐distressed broilers. Methods: In a completely randomized design with 4 × 2 factorial arrangement of the treatments, 320 24‐day‐old Ross 308 chickens, with average initial weight of 1220 ± 10 g were divided into eight treatments included sesame oil, tallow, sunflower oil and palm oil in either 22 or 32 degree of centigrade temperature. The broiler performance of each fat source‐treated group was not different in this experiment and decreased significantly in heat stress condition. Results: Heat stress showed a significant increase on fat, energy and ash content of thigh muscle. Tibia absolute length, width, ash and bone breaking strength were affected by fat source and increased when sesame and sunflower oil were used. Data analysis revealed that hot temperature decreased tibia weight, length, width, ash and bone breaking strength. Heat stress led to decrease of immune system parameters. Conclusion: Results suggest that there is no beneficial effect of broiler performance due to adding different sources of fat in broiler chicken diet under hot condition. Furthermore, the unsaturated fatty acids could improve the profile of fatty acids in thigh and enhance immune responses in broiler chickens. [ABSTRACT FROM AUTHOR]