EVALUATION OF THE HORMONAL RESPONSE OF COWS TO GNRH ADMINISTRATION IN THE POSTPARTUM PERIOD

The reactivity of the pituitary gland to exogenous GnRH was tested in a group of 12 cows, selected at random after parturition. The preparations Dirigestran inj. Spofa and Supergestran inj. Spofa were used for the stimulation. The preparations were administered twice (the 12th and 13th day post partum) by i.m. injection of 2 ml (80 mu-g) of Dirigestran inj. Spofa and 2 ml (50 mu-g) Supergestran inj. Spofa. Blood was sampled for 40 h. The average concentrations of the hormones (LH, FSH, prolactine, 17 beta-oestradiol and progesterone) were tested according to periods: before administration, after the first administration (12th day p.p.), after second administration (13th day p.p.) and at the end of the experiment. The results show that GnRH administration produced a significant response in LH levels both 12 and 13 days after parturition. Dirigestran inj. Spofa increased LH level after the first administration by 4.03 mu-g per litre, as compared with the control. Supergestran inj. Spofa, in turn, produced an increase of up to 5.76 mu-g per litre. The response to the second administration (13th day p.p.) is smaller: LH level is increased by 1.63 mu-g per litre by Dirigestran inj. Spofa and by 0.96 mu-g per litre by Supergestran.