Mehmet Ali Erfidan, Durmuş Fatih Başer
Pumpkin (Cucurbita pepo L.) seed oil (PSO) is rich in polyunsaturated fatty acids and bioactive compounds, but evidence regarding its biological effects in small ruminants remains limited. This study evaluated the effects of oral PSO supplementation in 45 clinically healthy weaned male Pırlak lambs with a mean initial age of 119.64 ± 35.25 days and a mean initial body weight of 37.55 ± 9.77 kg, allocated to three groups: control (n = 9), 0.5 mL/kg PSO (n = 18), and 1 mL/kg PSO (n = 18). PSO was administered orally once daily for 45 days. Body weight was measured, and blood samples were collected on days 0, 15, 30, and 45. Serum growth hormone, immunoglobulin G (IgG), oxidative status, and selected biochemical parameters were evaluated. PSO supplementation did not significantly affect body weight gain or serum growth hormone concentrations. Total oxidant status was lower in both PSO groups than in the control group on day 30, whereas the oxidative stress index was lower in the 1 mL/kg group than in the control group on day 45. Serum IgG concentrations were higher in the PSO groups throughout the study, although between-group differences were already present at baseline. Serum high-density lipoprotein cholesterol (HDL) concentrations increased over time, particularly in the 1 mL/kg group, whereas low-density lipoprotein cholesterol (LDL) concentrations remained unchanged. Serum glucose concentrations decreased over time and were lower on day 45 than at baseline. No consistent dose-dependent adverse changes were observed in liver or kidney function indicators. Oral PSO supplementation did not improve growth performance but was associated with selective changes in oxidative balance and lipid metabolism without evident hepatic or renal adverse effects. Longer-term studies are required to confirm these effects and clarify their biological significance.