Cereals, hay and straw naturally enriched in Se by use of fertilizers in horses diets: effects on a standardized exercise test
Hornick, Jean-Luc; Art, T; Pincemail, J; Defraigne, J.O; Dotreppe, O; Diez, M; Paeffgen, S; Fayt, J; Istasse, L; Dufrasne, I (2008)
Agrifood Research Working papersMTT:n selvityksiä
Selenium (Se) is a trace element of importance for animal health. Selenate, contained in fertilizers is naturally transformed in organic Se forms by the plants. Three g Se/ha were applied with the fertilizer in pastures for hay production and 4 g Se/ha were spread with the third nitrogen application on winter barley and on spelt fields. These feedstuffs along with similar feedstuffs grown without Se were used in a 570 g/kg concentrate-430 g/kg roughage diet. They were offered to six horses during two 56 days periods, transition excluded, of a cross-over design. On the end of each period the horses were submitted to a welldefined treadmill training. The Se concentrations were 63 and 297ìg/kg DM in the control and Se diets. Plasma Se concentrations were on average 111.9 ± 3.67 ìg/l and 142.7 ± 3.16 ìg/l (P<0.001) in the control and Se groups. In the control group one horse suffered from myopathy at the end of the test. When the horses were offered the control diet the speed of the treadmill was 3.9, 4.2 and, 4.6 m/sec in order to achieve the targeted steps of the standardized exercise; the corresponding speed with the Se diet was 3.8, 4.1 and 4.4 m/s. The recovery in both heart and respiratory rates were improved after the test. Before the exercise, the LDH activities were similar in both groups while AST and CPK activities tended to be lower with Se (400 ± 11.5 vs. 843 ± 278.3 IU/l, P<0.19, 231 ± 22.4 vs. 267 ± 48.1 IU/l, P<0.29). One hour after the test, the activities of two enzymes -AST and LDH- increased to a much lesser extend in the Se group than in the control group (463 ± 20.3 vs. 400 ± 11.5 and 1010 ± 196.3 vs. 843 ± 278.3 IU/l for AST; 952 ± 265.1 vs. 572 ± 9.1 and 1117 ± 170.3 vs. 572 ± 108.6 IU/l for LDH). By contrast, the extend of the increase in CPK activity was larger in the Se group (2795 ± 1723.9, 534 ± 132.0 and 231 ± 22.4 IU/l vs. 1586 ± 1024.4, 332 ± 70.9 and 267 ± 48.1 IU/l one and six hours after the test). It appeared, thus, that the feeding of Se enriched feedstuffs reduced the harmful effects of exercise in horses.
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