CHANGES IN THE SERUM CONCENTRATIONS OF GONADOTROPINS AND ESTRADIOL INPERIPUBERTAL CHINESE BEIJING-BLACK GILTS

Four gilts of the Chinese Beijing Black breed, all from the same litte r, had their blood serum concentrations of luteinizing hormone (LPI), follicle stimulating hormone (FSH) and oestrogens (E(2)) measured by r adioimmunoassay at intervals of 20 days between the ages of 5 and 185 days. The concentrations of LH declined sharply between days 5 to 25 a nd remained low until rising again from day 85 and reaching a peak at day 105 before declining again and remaining constant. The concentrati ons of FSH increased from day 85, peaking at day 105, followed by a sl ow decline to day 185. Serum E concentrations were high at day 5 then decreased dramatically, but increased considerably at (2)185 days. The se results are similar to those reported from European breeds.