Dietary tannins can exert either positive or negative effects on ruminants’ nutrition and performance. Pistachio hull (PH) is a by-product containing high amount of tannin. Herein we determined the effects of replacing different levels of alfalfa with PH on feed intake and digestibility of nutrients in total tract, rumen and post-rumen in Balochi male lambs. Three male lambs (35 ± 2 kg live weight) equipped with ruminal and abomasal cannula were randomly assigned into a changeover 3 × 3 design and fed the experimental diets for 35 d, 20 d adaptation, 5 d collection and 10 d break time between the 3 periods. Treatments were: 1) control (alfalfa), 2) 15% alfalfa+15% PH and 3) 30% PH (DM basis). Statistical analysis was performed using the MIXED procedure of SAS. Least squares means were separated using the LSD. Total dry matter intake (DMI), organic matter intake (OMI), DMI and OMI per kg of body and metabolic weight, CP, ADF, NDF and fat intake were not different between treatments. Total tract and ruminal digestibility for DM, OM, ADF and NDF was not significantly affected by the diets, but CP in total tract and its ruminal digestibility were linearly decreased with 66.03, 60.11 and 55.50% for total tract (P = 0.011 and SEM = 1.616) and 59.97, 53.67 and 49.17 for ruminal digestibility (P = 0.022 and SEM = 1.718) for 0, 15 and 30% PH respectively. Total tract and ruminal digestibility of fat were linearly increased with 78.97, 80.37 and 82.43% for total tract (P = 0.025 and SEM = 0.529) and 11.98, 17.47 and 21.98 for ruminal digestibility (P = 0.027 and SEM = 1.558) as the amount of PH in the diet increased. Post-ruminal digestibility of OM, Fat, ADF and NDF was not significantly affected by the diets while DM decreased (P = 0.037 and SEM = 0.419) from 29.03 to 28.64 and 27.31 and CP increased (P = 0.049 and SEM = 0.642) from 7.90 to 10.52 and 12.21 for 0, 15 and 30% PH respectively.

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