Plasma steorid profile in goats:age related changes

Abstract

Testicular size and plasma testosterone levels were measured in the male, and concentrations of oestradiol 17B and progesterone in t h e female goats , from 4 days to 40 weeks of age. All steroids were mea s ured in plasma usi ng a highly specific radioimmunoassay ( IUA). A gradual increase in size of the testis wa s observe d during the first 12 weeks followed by an abrupt increase by week 14. The testis s iz e was maximum in males 19-22 weeks in age . The peripheral testosterone levels \\'ere less than 55 ng/lOO ml during the first week of life and increased significantly at the age of 12-17 weeks (mean value of 105 ng/lOO ml). Testosterone levels fluctu a ted between 63 and 121 ng/lOO ml during the next 10 weeks and peak levels were observed at week 34 . Plasma oestradiol levels which were relatively higher during the first week of life (mean value of 56 ng/ml ) , subsequently fell to a mean VUlue of 32 pg/ml in females 10-27 weeks of age . A rise in oestradiol levels was recorded in 38-40 l-ieek old animals (mean value of 62 pg/ml) . Progest erone l evels rose gradually between 1st and 24t h week after birth. A marked increase in plasma progesterone l evels in Ceillales was found between 27-40 weeks of age (mean value of 206 ng/lOO ml).