THE VARIATION OF TRIIODOTHYRONINE (T 3) LEVEL IN MILKING COWS EXPOSED TO DIRECT SOLAR RADIATION
2003, 4 (4) p. 307-312
Very hot summers, during the last years, with intense solar radiation, determined us to study the effect of this radiation on milking cows. In the paper we have determined the level of triiodothyronine (T3), thyroid hormone, which varies in the case of cow’s organism exposure to heat stress. The determinations were made on two groups of ten milking cows per each, one group maintained in the stable for all the period and another on the pasture during the days with intense solar radiation. The determinations were made using RIA method, in Endocrinology Clinic in Cluj-Npoca, using the serum obtained from the blood drawn in the morning and evening. The results show a significant decrease of the triiodothyronine level in cow’s expose to direct solar radiation. These results are concordant with those in the literature.