Objective: The purpose of this study was to establish a method for the determination of T3 (triiodothyronine) and T4 (thyroxin) hormone concentrations in plasma, whole milk and after ethanol extraction, as well as to calculate the partition coefficient milk/plasma.
Methods: Ten Holstein Romanian friza milking cows were used to test the efficiency of the method. T3 and T4 were determined by an immunochemical ELISA competitive assay.
Results: Medium value of T3 in plasma was 2.78 ±1.53 ng/ml (4.27±2.35 nmol/l), in whole milk 3.72±1.44 ng/ml (5.71±2.21 nmol/l) and in extracted milk 4.97±1.67 ng/ml (7.63±2.56 nmol/l). Mean value of T4 in plasma was 50.97±7.30 ng/ml (65.60±9.39 nmol/l), in whole milk 2.12±0.87 ng/ml (2.73±1.12 nmol/l) and in extracted milk 3.60±1.15 ng/ml (4.64±1.48 nmol/l). Extraction from milk presented a good efficiency of 94.39% for T3 and 101.30% for T4.
Conclusion: The values obtained are in the concentration range reported by literature data for T4 and T3 from plasma and milk.
Determination of Triiodothyronine and Thyroxine from Plasma and Milk of Lactating Cow
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