Serum thyroid hormone levels in colostrum deprived piglets and calves

The level of thyroxine (T4), triiodothyronine (T3) and reverse triiodothyronine (rT3) was measured in blood of colostrum deprived calves and piglets and compared with appropriate control animals which were fed colostrum and milk according to a regular farm schedule. In most of cases, the levels of iodothyronines measured were significantly decreased in colostrum deprived (CD) calves between 36 h and 14 d of age. In piglets, the levels of iodothyronines were measured up to 72 h of age only and no remarkable differences were found between controls and CD animals. The concentration of T3 in pig milk after extraction with alkalized ethanol was estimated with radioimmunoassay and, at 1 week after delivery, it was 0.78 +/- 0.084 nmol 1(-1) (n = 10).