[Hormonal reactions in fattening bulls and cows during a three-week butyric acid exposure].

During a three-week intraruminal butyric acid resp. Na-butyrate load (1 g/kg body weight) we investigated the hormones insulin, cortisol, triiodothyronine (T3) and thyroxin (T4). Distinct effects on insulin concentration were found during the diurnal course which was after butyric acid application in the morning for nine hours depressed followed by a surplus incretion. In the morning the anteprandial concentrations of insulin, cortisol, T3 and T4 were not changed in the whole time. One cow was ill on ketosis and showed strong changes of hormones.