Lipid utilization efficiency and metabolic responses in lactating fat-tailed Turki-Qashqaei ewes fed graded levels of cracked safflower.

Although lipid supplementation is common in small ruminant diets to boost energy and essential fatty acids, little is known about how fat-tailed ewes adapt physiologically and utilize lipids during lactation. We addressed this gap by feeding graded levels of cracked safflower (0%, 3%, and 6% of dry matter) in lactating fat-tailed Turki-Qashqaei ewes (n = 12 per treatment). Nutrient intake relative to metabolic body weight (BW0.75), apparent total-tract digestibility (acid-insoluble ash method), rumen fermentation (pH, ammonia-N, total volatile fatty acids and acetate: propionate ratio), blood metabolites (glucose, β-hydroxybutyrate, non-esterified fatty acids (NEFA), triglycerides, total protein and albumin), and lipid utilization indices (milk fat yield per ether extract intake and milk long-chain fatty acid output per linoleic acid intake) were evaluated. Increasing safflower inclusion linearly elevated ether extract and linoleic acid intake (P < 0.05) but reduced digestibility of dry matter, organic matter, ether extract, neutral detergent fiber, and acid detergent fiber (P < 0.05). Rumen fermentation remained largely stable. At 6% inclusion, blood glucose decreased while NEFA and triglycerides increased (P < 0.05). Milk fat yield increased (P < 0.01), but lipid utilization indices showed nonlinear responses, consistent with metabolic regulation of lipid use. The results demonstrate that ruminal biohydrogenation and post-absorptive constraints limit efficient use of elevated unsaturated fatty acids. In lactating fat-tailed ewes, lipid supplementation primarily influences nutrient utilization efficiency and metabolic responses rather than producing linear productive gains, providing insights into lipid metabolism that may support physiologically based diet formulation for fat-tailed sheep breeds.