Effects of Dietary Nettle (Urtica dioica) Leaf Powder on Performance, Welfare, Hematological Profile, and Oxidative Status in Broiler Turkeys

Medicinal plants, such as nettle (Urtica dioica), are increasingly popular as sustainable alternatives to synthetic growth promoters and antioxidants in poultry production. The present study aimed to evaluate the effects of dietary nettle leaves on growth performance, welfare indicators, hematological and biochemical parameters, and oxidative status of broiler turkeys (Meleagris gallopavo) reared under intensive conditions. Seventy-two turkeys were randomly assigned to one of three dietary treatments from 3 to 15 weeks of age, including a control diet (CN), a diet with 3% nettle leaf powder (N3), and a diet with 6% nettle leaf powder (N6). Growth performance was monitored until week 13, while blood, carcass, and organ parameters were measured at the end of the trial. Mortality occurred only in the control group (3.33%), while there was no mortality in groups N3 or N6. Growth performance was significantly influenced by diet and sex. Male turkeys fed the N3 diet achieved higher final body weight compared to those receiving the CN or N6 diets. Conversely, no growth-promoting effect was observed in female turkeys. Female turkeys receiving the N3 diet exhibited lower final body weight and a higher feed conversion ratio than those in the CN group, indicating reduced feed efficiency. Nettle supplementation had no significant effect on carcass yield, organ development, or welfare indicators, including feather cleanliness and tarsal and plantar lesions. Hematological parameters, notably mean corpuscular volume, mean corpuscular hemoglobin, and platelet count, were significantly affected by nettle supplementation diets, whereas biochemical parameters remained within physiological ranges, indicating preserved systemic homeostasis. Dietary nettle supplementation enhanced antioxidant status, with both supplemented groups exhibiting significantly increased total antioxidant capacity, as measured by 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid; ABTS) radical scavenging activity, and a decrease in lipid peroxidation, assessed by thiobarbituric acid-reactive substances (TBARS), compared to the control group. Nettle leaf supplementation enhanced antioxidant defenses without compromising turkeys' welfare. A sex-dependent pattern was observed in growth performance parameters, with male turkeys exhibiting a greater response than females at the 3% nettle leaf inclusion level. However, both sexes exhibited consistent increases in antioxidant levels, highlighting the potential of nettle as a natural supplement in turkey production.