Effects of norgestomet on follicular developments and hormonal profiles during dioestrus and proestrus of oestrous cycle in crossbred cows

The influence of norgestomet on the secretory patterns of progesterone, oes tradiol and luteinizing hormone during dioestrus and proestrus of oestrous cycle were studied in 12 crossbred cows. In all the cows, the oestrus was i nitially synchronized by 2 intramuscular injections of prostaglandin F-2 al pha (PGF(2)alpha) at 12 days apart. At oestrus the cows were divided in to groups I and 2. In group 1, the norgestomet implant was implanted at day 9 (dioestrus) of the oestrous cycle. whereas in group I it was implanted on d ay 18 (proestrus) of the oestrous cycle. The onset of oestrus and LH surge were significantly (P <0.01) earlier in group 2 than in 1. Norgestomet duri ng dioestrus has no influence on the secretory patterns of the progesterone oestradiol and luteinizing hormone, whereas, during proestrus, increased t he secretory patterns of luteinizing hormone and oestradiol.