Antioxidant status and mammary health of dairy cows fed on diets supplemented with selenite

Abstract

The peripartum period, which comprises the three weeks before and after parturition in dairy cattle, is characterized by marked physiological, metabolic and endocrine changes as the cow transitions from the metabolically demanding states of pregnancy to lactation. The dairy cows are at risk, and they are prone to various diseases (mastitis, metritis, ketosis) that could affect their productivity associated with immune suppression. The study aimed at evaluating the effect of peroral supplementing selenite at various concentrations on the selenium concentration (Se), glutathione peroxidase (GPx) activity and malondialdehyde (MDA) level of blood on the occurrence of mastitis in dairy cows during peripartum period. Forty five multiparous Holstein cows averaging 550 ± 50 kg of body weight in 2 to 4 parity were divided into three equal groups (n=15) at the end of gestation. The first experimental group (D1) was fed with addition of selenite at a dose of 0.3 mg.kg -1 of dry matter (DM). The second group (D2) was added the same form of selenium as in group D1 at a dose of 0.5 mg.kg -1 of DM. The control group (C) of cows) was fed with only selenium from native sources in content 0.2 mg per kg of DM. The blood samples for Se detection and activity of GPx were collected from the jugular vein of all tested cows month before the expected time of calving, on parturition day and at 14 th day after calving. In group (D2) with addition of selenium at a dose of 0.5 mg/kg of DM in diet, were increased the plasmatic concentration of selenium in blood plasma and colostrum as well as reduced levels of MDA. As a result, antioxidative protection was observed decreased occurrence of mastitis by 13.3% in D2 group during the first two weeks of lactation. The application of selenium in feed have economically significant impacts such as the reduction of mastitis and is one of the ways how to increase selenium in animal food and products.