Effect of grazing pasture with a low selenium content on the concentrations of triiodothyronine and thyroxine in serum, and GSH-Px activity in erythrocytes in cows in Chile

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dc.contributor.authorContreras, P.A.
dc.contributor.authorWittwer, F.
dc.contributor.authorMatamoros, Roberto
dc.contributor.authorMayorga, I.M.
dc.contributor.authorVan Schaik, G.
dc.date2005
dc.date.accessioned2012-03-01T14:23:12Z
dc.date.available2012-03-01T14:23:12Z
dc.date.issued2012-03-01
dc.description.abstractAIM: To determine the effect of grazing pasture that had a low selenium (Se) concentration on serum concentrations of triiodothyronine (T3) and thyroxine (T4), and erythrocyte glutathione peroxidase (GSH-Px) activity in dairy cows. METHODS: Forty pregnant Friesian cows were grazed on pasture that contained 0.03-0.04 ppm Se on a dry matter (DM) basis. Two months before parturition, 20 cows were randomly selected and treated with 1 mg Se/kg bodyweight subcutaneously, as barium selenate (Group Se-S). The other group (Se-D) was not supplemented. Blood samples were taken before supplementation (-60 days) and 30, 60, 90, 180 and 270 days after parturition, for determination of concentrations of T3 and T4 in serum, and GSH-Px activity in erythrocytes. RESULTS: Erythrocyte GSH-Px activity in the Se-D group was <60 U/g haemoglobin (Hb) throughout the experiment. Supplementation increased (p<0.05) activities to >130 U/g Hb throughout lactation. Mean serum concentrations of T4 in Se-D and Se-S cows increased from 23.7 (SEM 0.7) and 23.4 (SEM 0.8) nmol/L, respectively, in the prepartum period to 69.6 (SEM 0.1) and 67.6 (SEM 0.2) nmol/L, respectively, at 180 days of lactation (p<0.01), and no effect of Se supplementation was evident. Serum concentrations of T3 in Se-D cows decreased (p<0.05) from 1.6 (SEM 0.1) nmol/L prepartum to 1.0 (SEM 0.2) nmol/L at the beginning of lactation, and remained lower (p<0.05) than those in the Se-S cows which did not decrease after calving and ranged from 1.9 (SEM 0.1) to 2.4 (SEM 0.2) nmol/L throughout lactation. CONCLUSIONS: Serum T3 concentrations decreased during early lactation in unsupplemented cows grazing pastures low in Se (0.03-0.04 ppm) and both serum T3 and erythrocyte GSH-Px activities were consistently lower throughout lactation compared with Se-supplemented cows. Se supplementation had no effect on serum T4 concentrations.es
dc.formatPDFes
dc.identifier.citationNew Zealand Veterinary Journal, Vol.53, N°1, 77-80, 2005es
dc.identifier.urihttps://repositoriodigital.uct.cl/handle/10925/829
dc.language.isoenes
dc.sourceNew Zealand Veterinary Journales
dc.subjectVacases
dc.subjectGanadoes
dc.subjectSelenioes
dc.titleEffect of grazing pasture with a low selenium content on the concentrations of triiodothyronine and thyroxine in serum, and GSH-Px activity in erythrocytes in cows in Chilees
dc.typeArtículo de Revistaes
uct.carreraMedicina Veterinariaes
uct.catalogadorFGEes
uct.comunidadRecursos Naturaleses
uct.facultadFacultad de Recursos Naturaleses
uct.indizacionISIes
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