Endocrine Abstracts

Thyroid hormones play an important roles during pregnancy and lactation. During pregnancy the foetus depends entirely on the dam for the supply of nutrients and after parturition for the formation of colostrum. To meet out these needs the dam attempts to reset up its endocrine function including thyroid gland. There is also a change in body metabolic rate and some of the related biochemical components which are mainly controlled by thyroid hormones. Therefore an experiment was conducted to delineate the changes in plasma T₃ and T₄ concentrations during pregnancy in Black Bengal goats. Blood samples were collected through jugular venipuncture from five black Bengal goats on day 115th, 119th, 122th, 126th, 129th, 133th, 136th, 139th, 142th, 146th of pregnancy and also on the day of kidding. Plasma T₃ and T₄ concentrations were estimated by radioimmunoassay. Plasma T3 concentrations increased from 1.97±0.26 nmol/l on day 115th of pregnancy to 2.85±0.42 nmol/l on the day 119th which then decreased to 1.49±0.20 nmol/l on the day of kidding. Plasma T₄ concentrations increased from 80.40±0.26 nmol/l on day 115th of pregnancy to 81.76±6.72 nmol/l on the day 126th and then decreased to 39.68±5.20 nmol/l on the day of kidding. It is concluded that decline in plasma T₃ and T₄ concentrations during late pregnancy indicate the inhibitory effect of glucocorticoid which rise before parturition on pituitary-thyroid axis.