Evaluation of different prophylactic methods against selenium deficiency in sheep grazing on range in Southwestern Spain

Abstract

Various selenium treatments were given to four groups of 50 ewes (control=no selenium treatment, BS=barium selenate 1 mg Se/kg liveweight subcutaneously, SS=sodium selenite 0.03 mg Se/kg liveweight subcutaneously, SA=selenium plus albendazole 0.162 mg Se/kg liveweight per os) in the last trimester of pregnancy. Blood and plasma GSHPx activities 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 and 72 days after treatment). These activities were also measured in 15-day-old lambs from the control and treated ewes. In addition, the evolution of blood GSHPx activity in the four groups throughout the experiment was compared with plasma GSHPx activity. Finally, a correlation study was performed on the values of GSHPx activity between the ewes and their lambs. The results for blood GSHPx activity obtained in the last 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 activities 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 ewes and their lambs were 0.76 for blood and 0.94 for plasma, both statistically significant ( P<0.05). The best treatment was barium selenate. At medium stages, the efficacy of a sodium selenite compound could not 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.