Nanoparticles of Selenium with Stronger Physiological Effects (TBARS) [15]. What should be noted about the changes in hematological parameters is the effect of selenium on survivability of the RBCs. As a result, the present study was designed to determine hematological changes and the levels of oxidative stress and lipid peroxidation of cellular membrane changes in healthy sheep in response to selenium nanoparticles and sodium selenite supplementation using TBARS assay. Materials and Methods Animals Fifteen healthy, 5- to 12-month-old Lori–Bakhtiari sheep were selected and randomly divided into three groups. The sheep were orally given nano red selenium (group I, 1 mg/kg BW) and sodium selenite (group II, 1 mg Se/kg BW) for 10 consecutive days. The control group was given distilled water (group III). Ration During the study period, sheep were fed alfalfa hay and barely without selenium supplementation. The mean value of Se (mean ± SE) in the diet on dry matter basis was 0.49 ± 0.15 mg/kg. Nano Red Selenium Preparation Nano red elemental selenium particles (nano-Se) were synthesized as described previously by Zhang et al. [16]. The material includes SeO2 and ascorbic acid. The ascorbic acid solution was added into the aqueous solution of SeO2 to initiate the reaction. After the addition of ascorbic acid, nano red selenium particles began to form, causing the solutions to change from colorless to red. The red color of the ascorbic acid-treated solutions suggested that the selenium was present either in its amorphous or monoclinic forms [16]. The sizes of the obtained nano-Se particles ranged from 80 to 200 nm as determined by scanning electron microscopy. Sampling Two blood samples were collected from the jugular vein of sheep into acid-washed polyethylene tubes at the beginning of the experiment (day 0) and subsequently on days 10, 20, and 30. One tube contained heparin as the anticoagulation agent for hematological parameter analyses, and the other tube was without anticoagulation, for measuring TBARS. TBARS Assay Sample Preparation A serum sample of 0.5 ml was mixed with 0.5 ml sterile distilled water in a labeled 1.5-ml micro- 303 centrifuge tube. A blank sample (for calibration) was also prepared by adding 2 ml of the reagent to 1 ml distilled water. Reagent Preparation Trichloroacetic acid (10%) (w/v), 0.375% thiobarbituric acid (TBA) (w/v), and 0.025 N HCl were mixed and heated gently until TBA was dissolved completely. Performing Assay Two milliliters of the reagent was added to each sample, and the microtubes were incubated in a boiling water bath for 10 min. Then they were placed at room temperature for 15 min and centrifuged at 1,000×g for 10 min at 4°C. Finally, the supernatants were transferred to new labeled tubes, and absorbances of the samples were measured at 535 nm against a blank sample. Antioxidative activity was calculated by adding the malondialdehyde index (1.056 ×105 M−1 cm−1). Hematological Parameter Assay Hematological parameters including red blood cell (RBC) count, packed cell volume (PCV) value, hemoglobin (Hb) concentration, and white blood cell (WBC) counts were measured by routine procedures [17]. Hemoglobin was measured photometrically using the cyanomethemoglobin method, and PCV levels were determined using a micro- hematocrit centrifuge (12,000×g for 5 min). WBC measure- ment was conducted using the manual standard method. Differential leukocyte counts were performed on routinely prepared Geimsa-stained blood films using the cross-sectional technique [18]. Statistical Analysis The results were analyzed statistically using the Sigma State (second version) program and by one-way analysis of variance tests. Also, the Tukey test and Dunnett's method were used for further evaluations at the level P<0.05. Results TBARS The observed TBARS values in each group on different days of sampling are presented in Table 1. It should be noted that there were no significant differences in the TBARS values of the three groups at the beginning of the experiment (day 0) and on the 10th day, but a significant increase had occurred in groups 1 and 2 in comparison with the basal level on the 20th and 30th day (P< 0.05). In group 1 (nano-selenium), on the 20th and 30th day, the values of