| Abstract: | The objective of the study was to check a contingent negative effect of repeated treatment of heifers by PGF2 alpha--Oestrophan (SPOFA)--on the course and quality of their ovarian activity and external heat signs. Changes in progesterone concentrations were evaluated three times a week. Three heifers were subjected to treatment eight times and two heifers nine times. Of 42 applications of Oestrophan (SPOFA) the response was positive in 95.2% (forty heats). When Oestrophan (SPOFA) was administered on the fourth and sixth day of the sexual cycle, in two cases no heat nor luteolysis of corpus luteum was detected; this was demonstrated by hormonal investigation. Of the forty evaluated heats, 82.5% were classified as strongly and medium expressive, the remaining were weakly expressive. The onset of heat was found to be on the average 72.6 hours after Oestrophan (SPOFA) administration, in 9.1% of the cases the heat started about 48 hours after administration, 12.4% of cows showed the heat signs between 72nd and 96th hours. |
