Effect of some trace mineral-vitamin supplements on thyroid hormones and blood metabolites of high production Holstein cows during summer season

This study was conducted to evaluate the effects of some nutritional and injectable mineral-vitamin supplements on thyroid hormones (T₃ and T₄) and blood metabolites in transition dairy cows. One hundred multiparous Holstein cows were randomly assigned to four groups. The treatments were consisted of: (1) control, (2) injection of Se- vitamin E supplement, (3) Feed minerals- vitamins bolus supplement, and (4) injection and feed mineral-vitamin supplements. The injectable supplement was contained vitamin E and Se and the dietary bolus was contained Cu, Co, Se, Mn, I, Zn, and vitamins A, E and D₃. The data showed nutritional bolus or injectable supplement had no effect on concentration T₃ and T₄ hormans. Nutritional bolus increased (P<0.05) total blood protein at parturition time. The group supplemented with injectable vitamin E-Se along nutritional bolus had higher triglyceride in the first month of lactation (P<0.05). The treatments had no effect on blood urea nitrogen. It was concluded that the nutritional bolus had positive effects on some of blood metabolic profile.

Keywords: Mineral- vitamin supplements, Dairy cow, Blood metabolites, Thyroid hormones