EVALUATION OF DIFFERENT PROPHYLACTIC METHODS AGAINST SELENIUM DEFICIENCY IN SHEEP GRAZING ON RANGE IN SOUTHWESTERN SPAIN

Various selenium treatments were given to four groups of 50 ewes (cont rol = no selenium treatment, BS = barium selenate 1 mg Se/kg liveweigh t subcutaneously, SS=sodium selenite 0.03 mg Se/kg liveweight subcutan eously, SA = selenium plus albendazole 0.162 mg Se/kg liveweight per o s) in the last trimester of pregnancy. Blood and plasma GSHPx activiti es were measured in the ewes before treatment, a few days after it, at the end of pregnancy and in the post-parturition period (0, 15, 42 an d 72 days after treatment). These activities were also measured in 15- day-old lambs from the control and treated ewes. In addition, the evol ution of blood GSHPx activity in the four groups throughout the experi ment was compared with plasma GSHPx activity. Finally, a correlation s tudy was performed on the values of GSHPx activity between the ewes an d their lambs. The results for blood GSHPx activity obtained in the la st sampling in adult sheep, 72 days after treatment were: 37.00 +/- 15 .21 IU/g Hb for control, 236.20 +/- 19.66 IU/g Hb for BS, 43.20 +/- 10 .42 IU/g Hb for SS and 57.40 +/- 7.61 IU/g Hb for SA, For plasma GSHPx activity the results were: 101.80 +/- 13.20 IU/L for control, 209.00 +/- 41.00 IU/l for BS, 101.00 +/- 8.00 IU/l for SS and 86.60 +/- 14.90 IU/l for SA. In the lambs blood GSHPx activities were: 50.57 +/- 8.49 IU/g Hb for control, 249.00 +/- 44.55 IU/g Hb for BS, 53.29 +/- 11.95 IU/g Hb for SS and 65.86 +/- 6.17 IU/g Hb for SA. Plasma GSHPx activi ties in lambs were: 66.40 +/- 10.02 IU/l for control, 363.43 +/- 57.38 IU/l for BS, 89.00 +/- 32.87 IU/l for SS and 83.37 +/- 7.33 IU/l for SA. The correlation coefficients obtained from GSHPx values of the ewe s and their lambs were 0.76 for blood and 0.94 for plasma, both statis tically significant (P < 0.05). The best treatment was barium selenate . At medium stages, the efficacy of a sodium selenite compound could n ot be properly evaluated by the measure of plasma GSHPx activity. This GSHPx enzyme determination in ewes, in blood and plasma, is adequate to make a prediction and to prevent selenium deficiency in lambs. (C) 1998 Elsevier Science B.V. All rights reserved.