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Effects of Supplementary Selenium Source on the Blood Parameters in Beef Cows and Their Nursing Calves

Stacey A. Gunter, Paul A. Beck, Dennis M. Hallford
Biological trace element research 2013 v.152 no.2 pp. 204-211
Cynodon dactylon, beef cows, blood, blood chemistry, breeding season, calves, calving, dietary mineral supplements, enzyme activity, feed supplements, glutathione peroxidase, herds, insulin-like growth factor I, lactation, minerals, models, pastures, selenium, sodium selenite, triiodothyronine, yeasts
Over 2 years, 32 beef cows nursing calves were randomly selected from a herd of 120 that were managed in 6 groups and were assigned to six 5.1-ha bermudagrass (Cynodon dactylon [L.] Pers.) pastures. Treatments were assigned to pastures (2 pastures/treatment) and cows had ad libitum access to 1 of 3 free-choice minerals: 1) no supplemental selenium (Se), 2) 26 mg of supplemental Se from sodium selenite/kg, and 3) 26 mg of supplemental Se from seleno yeast/kg (designed mineral intake = 113 g/cow daily). Data were analyzed using a mixed model; year and pasture were the random effects and treatment was the fixed effect. At the beginning of the calving and breeding seasons, cows supplemented with Se had greater (P < 0.01) whole blood Se concentrations (WBSe) and glutathione peroxidase activities (GSH-Px) than cows receiving no supplemental Se; cows fed seleno-yeast had greater (P </= 0.05) WBSe than cows fed sodium selenite, but GSH Px did not differ (P >/= 0.25) between the two sources. At birth and near peak lactation (late May), calves from cows supplemented with Se had greater (P < 0.01) WBSe than calves from cows fed no Se and calves from cows fed seleno-yeast had greater (P </= 0.01) WBSe and GSH-Px than calves from cows fed sodium selenite. Thyroxine (T4), triiodothyronine (T3), and the T4:T3 ratio in calves did not differ among treatments (P >/= 0.35). At birth, IGF-1 was greater (P = 0.02) in calves nursing cows with no supplemental Se than in ones with supplemental Se; in calves nursing cows with supplemental sodium selenite, IGF-1 did not differ (P = 0.96) from ones offered supplemental seleno-yeast. Selenium supplementation of gestating beef cows benefited cows and calves by increasing WBSe and GSH Px. The use of seleno yeast as a Se supplement compared to sodium selenite increased the WBSe and GSH-Px of both cows and their calves, yet had no effect on T4 conversion or IGF-1 concentrations.