Abstract

Selenium acts at the reproductive and immune system level. The toxicity, bioavailability and action depend on the type of selenium given. It was evaluated if the source of selenium affects the percentage of pregnant sheep and leukocytes (immune cells of the white blood cell package). Twenty adult sheep randomly distributed in: control (T₁), sodium selenite (T₂), encapsulated yeast enriched with selenium (T₃), and powdered yeast with selenium (T₄) were used for five days before artificial insemination (AI), 300mg day^-1 animal^-1. Leukocytes were counted seven days before and up to 88 days after AI. A completely randomized design was used. For leukocyte data, a mixed model was used and, for gestation percentage, logistic regression. The powdered yeast with selenium (T₄) presented 100% of pregnancies and sodium selenite only 40%; while, the control sheep and those with encapsulated yeast enriched with selenium, 80% (P < 0.05). The cells that appeared in greater number were lymphocytes and neutrophils. Lymphocytes increased after day 13, with a maximum number on day 20 (p < 0.05). In T₂ the total number of lymphocytes decreased and that of monocytes increased. Basophils were increased at both T₃ and T₄. The selenium source is important in the presence of leukocytes and in the establishment and maintenance of pregnancy.

Keywords: Immune Cells; Organic Selenium; Inorganic Selenium; Sodium Selenite; Gestational Immunity; Sheep

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