فهرست نشریات علمی دسترسی آزاد ایران

This study aimed to determine the effects of energy levels and sources on growth performance, antibody titers, and the gene expression of pro-inflammatory cytokines in broilers exposed to heat stress. A total of 450 one-day-old Ross chickens were assigned to six dietary treatments and five replicates in a completely randomized design. Chickens received diets differentiated by the main energy source (corn grain and soybean oil) and energy level (equal, 3% or 6% lower or higher than Ross 308 recommendation). Treatments were as follows: corn grain and equal as Control (CON), 3% lower corn grain (T1), 6% lower corn grain (T2), corn grain and soybean oil, equal (T3), 3% higher corn grain and soybean oil (T4), 6% higher corn grain and soybean oil (T5). The room temperature was increased to 34°C (6-h daily) from day 12 to 42 of age to induce heat stress. The highest corticosterone level was observed in T1, T2, and T5 groups. The lowest antibody titers were observed in T2 group and the highest expression levels of pro-inflammatory cytokines genes were in chickens receiving T5 diet. The highest Feed Conversion Ratio (FCR) during the grower and finisher periods was observed in T2, and the lowest in T3 and T4. It was recommended to feed Ross broiler with a diet containing oil instead of a part of grain based on energy recommended by the strain recommendation.