Parameters of dietary selenium and vitamin E deficiency in growing rabbits

Abstract

4 × 5 growing female rabbits (New Zealand White) with an initial live weight of 610 ± 62 g were fed a torula yeast based semisynthetic diet low in selenium (<0.03 mg/kg diet) and containing <2 mg α-tocopherol per kg (group I). Group II received a vitamin E supplementation of 150 mg α-tocopherylacetate per kg diet, whereas for group III 0.40 mg Se as Na-selenite and for group IV both supplements were added. Selenium status and parameters of tissue damage were analyzed after 10 weeks on experiment (live weight 2355 ± 145 g). Selenium depletion of the Se deficient rabbits (groups I and II) was indicated by a significantly lower plasma Se content (group I: 38.3 ± 6.23 μg Se/mL plasma, group II: 42.6 ± 9.77, group III: 149 ± 33.4, group IV: 126 ± 6.45) and a significantly lower liver Se content (group I: 89.4 ± 18.2 μg/kg fresh matter, group II: 111 ± 26.2) as compared to the Se supplemented groups III (983 ± 204) and IV (926 ± 73.9). After 5 weeks on the experimental diets differences in the development of plasma glutathione peroxidase were observed. As compared to the initial status group (45.2 ± 4.50) pGPx activity in mU/mg protein was decreased in group I (19.1 ± 7.08), remained almost stable in the vitamin E supplemented group II (46.3 ± 11.2) whereas an elevated enzyme activity was measured in the Se supplemented groups III (62.4 ± 23.9) and IV (106 ± 19.9). In the rabbit organs investigated 10 weeks of Se deficiency caused a significant loss of Se dependent cellular glutathione peroxidase activity (GPx1) of 94% (liver), 80% (kidney), 50% (heart muscle) and 60% (musculus longissimus dorsi) in comparison to Se supplemented control animals. Damage of cellular Lipids and proteins in the liver was due to either Se or vitamin E deficiency. However damage was most severe under conditions of a combined Se and vitamin E deficiency. It can be concluded that the activity of plasma glutathione peroxidase is a sensitive indicator of Se deficiency in rabbits. The loss of GPx1 activity indicates the selenium depletion in various rabbit organs. Both selenium and vitamin E are essential and highly efficient antioxidants which protect rabbits against lipid and protein oxidation.