摘要
The aim of the study was to evaluate the impact of organic selenium supplementation （selenium yeast） vs. inorganic selenium （selenium selenite） on the expression of selected defensin genes in milk somatic cells （MSC） of dairy cows. Sixteen Polish Holstein-Friesian cows in second parity, with similar milk yield and milk composition were randomly divided into two equal groups. At the beginning of experiment, the animals were in the middle of their lactation curve （150, standard deviation （SD） = 26 d） and this experiment lasted 90 d. The basic diet, for both groups, consisted of corn silage, wilted grass silage and concentrates. The diet of control group was supplemented with commercial mineral and vitamin mixture with inorganic selenium and the for the experimental group daily selenium need was covered by the addition of Se-yeast （6 mg Se/cow/d）. Milk samples were collected three times during experiment （before experiment; on day 55; after the end the experiment）. Total RNA was isolated from milk somatic cells and the levels of transcripts of bovine β1-defensin （DEFB1）, β4-defensin （BNBD4）, β5-defensin （BNBDS）, β10-defensin （BNBD10） and lingual antimicrobial peptide （LAP） were measured with real time PCR, using glyceraldehyde 3-phosphate dehydrogenase （GAPDH） as a reference gene. The expressions of almost all studied genes were influenced by environmental conditions （very low and negative temperature）. However, BNBD4 （P 〈 0.05） and LAP （P ≤ 0.001 ） genes were influenced by selenium supplementation but in opposite ways, depending on the form of Se. These findings support that selenium is an important factor affecting the mRNA level in MSC, but the effect of the form of selenium might depend on genes.
