Silymarin as a Dietary Additive: Influence on Immune Function and Oxidative Stress in Broiler Turkeys

The present study aimed to evaluate the effects of silymarin on immune response, biochemical markers, and some traits of oxidative stress in broiler turkeys. The turkeys were fed ad libitum with a commercially prepared feed from the Agricultural Institute in Stara Zagora, supplemented with 2% silymarin over 126 days. Sixty-one-day-old female broiler turkeys were divided into two groups of 30. The control group received a standard age-matched feed without silymarin, while the experimental group received a feed supplemented with 2% silymarin. Serum lysozyme concentration, alternative complement activation pathway, and beta-lysin activity were not significantly affected by silymarin. Most biochemical parameters remained unaffected, except for uric acid levels, which were substantially lower in the silymarin-treated birds (P < 0.05). Indicators of oxidative stress were notably higher in the silymarin-treated group (P < 0.01), except for superoxide dismutase (SOD), where activity was significantly higher in the control group (P < 0.01). This experiment was carried out during the warm summer season. More studies are needed during different seasons of the year. Based on the results obtained, it can be concluded that silymarin has no significant immunomodulatory potential in turkeys but had a noticeable effect on oxidative stress indicators in the experimental group.