[Effect of temperature on the activity of the thyroid gland in 8-week-old chickens]

The authors carried out investigations on the influence of temperature (11 degrees C and 28 degrees C) on the thyroid function of 8-week-old Cornish chickens. Experiments on two groups of chickens (7 males and 7 females in each) lasted for two weeks. The chickens were kept in individual cages and fed fodder and drinking water ad libitum. The rooms were ventilated and the light was on for 24 hours. After 14 days of experiment the autors measured the weight of the thyroid per 100 g of body weight, 21 hr thyroid 125J uptake, and conversion ratio of inorganic iodine into bound organic iodine (CR). It was found that the body weight of chickens kept in high temperature was 16% higher than of those maintained in lower temperature. In both groups the males grew more quickly than the females. Low temperature increased the thyroid weight by 7% and CR by 48.5%. The differences in iodine conversion were statistically significant (p less than 0.01). In both groups higher thyroid activity in the females than in the males was observed.