Pistachio hull (PH) is a byproduct that has high tannin concentration. Tannins can reduce the digestion of nutrients, especially proteins. We aimed to evaluate the effects of diets containing tannin on plasma metabolic profile of Balochi male lambs. Pistachio hull as a tannin source (with 6.68% tannin and 9.95% total phenol content) was used in diets of 3 male lambs (35 ± 2 kg live weight) which were randomly assigned into a changeover 3 × 3 design. Treatments were: 1) control (alfalfa), 2) 15% alfalfa+15% PH and 3) 30% PH (DM basis). Blood samples were taken from the jugular vein at 0, 2 and 4 h after the 0800 h feeding for measuring glucose, total protein, blood urea nitrogen (BUN), albumin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglycerides and cholesterol. Data were analyzed as a repeated measurement design using PROC MIXED of SAS (P < 0.05), assuming the model included treatment, time, time × treatment as fixed effects and animal as random effect. Blood metabolites glucose, albumin, BUN, AST and ALT were not affected by the experimental diets (P = 0.778, P = 0.264, P = 0.281, P = 0.538 and P = 0.899 for glucose, albumin, BUN, AST and ALT, recpectively). Total protein was decreased as the dietary PH content (Tannin source) increased (P = 0.003). Plasma triglyceride concentration was significantly increased (P = 0.0008). The fat metabolite i.e., cholesterol (P = 0.913) was not influenced by PH content of diet.

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