Effects of the early incubation temperature on the muscle physiology, meat quality, bone strength and gait score in Ross broilers.

1. Modern broiler chickens are among the most efficient livestock in terms of resource requirements and production time. To maintain and improve production efficiency and meat quality and account for welfare problems, early interventions, such as incubation temperature, require investigation2. In this study, Ross 308 broiler eggs were incubated at either 36.5°C or 38.5°C on embryonic days (ED) 4-7. The control group eggs were incubated at a constant temperature of 37.5°C. Musculus pectoralis and musculus gastrocnemius samples were taken for the investigation of muscle physiology, and the tibia was sampled for bone strength analysis from chickens aged 35 and 36 d. In addition, meat quality was analysed and gait scoring was performed.3. The performance of chickens in the 36.5°C group was inferior to those in the other groups up to d 10 post-hatch, but compensatory growth was seen by d 35 of age. Meat quality was unaffected, but significant differences between sexes were observed. Males had lighter meat colour than females. Muscle glycogen and intramuscular fat were unaffected by the incubation temperature, but the muscularis pectoralis and gastrocnemius intramuscular fat contents were greater in males than in females, accompanied by the increased expression of enzymes involved in lipolysis. In the 38.5°C group, males had less bone elasticity than females, and the inverse was observed in the other groups. Gait scores were affected by sex but not incubation temperature.4. The results of this study showed a stronger effect of sex than incubation temperature on broiler muscle physiology, bone strength, performance and meat quality.