Biological effect of selenium supplementation during the pasture period of sheep, reared in some endemic areas of the Western Rhodope Mountain on selenium contentin the milk

摘要

The large number of different sheep species, their wide adaptability to forage quality and high genetic potential, makes possible their widespread dissemination. However, an imbalance of the main biogenic components (selenium, iodine) in mountainous areas could adversely affect the milk production and the daily secretion of essential macro and trace elements through the milk produced during lactation.This study was conducted with 16 lactating ewe's from Rhodope Tsigay breed, grown in endemic region of theWestern Rhodope Mountain - village Borino. The animals were divided into two groups - control and deficient group. Feed was prepared according ARC-norms with different amounts of selenium during the experimental period. During the lactating period, the sheep in the control group were additionally supplemented "per os" with 0.25 mg selenium / day in form of NaHSe03. Milk samples from both breeds were taken on the 30th and 60th day after the addition of selenium and were compared with the content of selenium at the beginning of the experiment. Low concentrations of selenium in the plant species (Se <60-70ug / kg fodder) during lactation (April-June) affect negatively the concentration of Se in sheep milk. Its amount in the ewe's milk increased reliably as a result of supplementation. Within 60 days, the levels of the element reached a normal values in the control group, while in the deficient animals critical values in the milk (20-30 ugSe /1) had been established. The effect of Se-supplementation on average daily secretion of macro- and trace elements was studied, as well as the changes in the milk production during the survey period. Recommendations for the inclusion of selenium supplements for small ruminants, bred in the endemic areas during the grazing period have been proposed.