Direct Oral Administration of Cold-Pressed Nigella sativa Oil in Neonatal Lambs: A Longitudinal Assessment of Systemic Safety and Hematobiochemical Responses

Evaluating the in vivo systemic tolerance of phytogenic feed additives is a crucial prerequisite before their widespread application in vulnerable newborn ruminants. This study aimed to investigate the systemic effects of orally administered cold-pressed Nigella sativa oil on the hematological and biochemical profiles of neonatal lambs (0–45 days of age) fed exclusively on colostrum and maternal milk. The pre-specified primary endpoint was the absence of clinically meaningful change in hepatorenal markers and complete blood count between groups over 45 days. Thirty-two single-born Merino lambs were divided into a treatment group that received 1.5 mL/day of the oil for the first 15 days of life and an untreated control group. Blood samples were collected on days 0, 7, 21, and 45 to evaluate both immediate and carry-over physiological effects. Using a covariate-adjusted linear mixed-effects model to account for baseline variances, the results demonstrated that the oil was physiologically well-tolerated. The supplementation exerted no significant adverse effects (p > 0.05) on hepatorenal markers or the measured acute-phase protein. The supplementation maintained neonatal energy metabolism stability without inducing artificial lipid suppression in serum triglycerides or total cholesterol levels. Furthermore, the oil preserved hematological homeostasis without negatively impacting red blood cell indices and modulated platelet distribution width indices without causing pathological thrombocytosis. In conclusion, the early direct oral administration of N. sativa oil is a physiologically well-tolerated supplement that supports basal metabolic and hematological stability in pre-ruminant lambs without inducing systemic disruptions within the parameters measured.