Effects of low-dose oleuropein diet supplementation on the oxidative status of skeletal muscles and plasma hormonal concentration of growing broiler chickens

1. Oleuropein (Ole) is a major phenolic compound in Olea europaea, with anti-oxidative, anti-obesity, and anti-inflammatory properties. To explore the effect of Ole on the physiology and metabolism of poultry, this study, evaluated the effects of feeding low-dose Ole on the growth performance, metabolic hormonal status, muscle oxidative status in growing broiler chickens. 2. Thirty-two 8-day-old chickens were assigned to four different treatments, and fed either 0 (control), 0.1, 0.5, or 2.5 ppm Ole-supplemented diets for 2 weeks. 3. There were no differences in the body weight gain, feed consumption, and feed efficiency during the feeding periods between the groups tested. Birds fed Ole 0.5- and 2.5 ppm-supplemented diets exhibited a significant decrease in muscle carbonyl content compared to the control group. In the group fed Ole 0.5 ppm, the mRNA expression levels of mitochondrial ROS-reducing factors: avian uncoupling protein and manganese superoxide dismutase, as well as peroxisome proliferator-activated receptor γ coactivator 1-α, sirtuin-1 and −3 (each of which co-ordinately induce the transcription of the previous two factors) were upregulated compared to the control group, and the changes were independent of plasma noradrenaline and thyroid hormone levels. The group fed Ole-2.5 ppm did not show such transcriptional changes, but exhibited a higher corticosterone concentration. 4. This study demonstrates that ingesting a low dose of Ole can reduce muscle oxidative damage, and that the suppression machinery may differ depending on the amount of Ole ingested by growing broiler chickens.