Seasonal variation in blood hormones (progesterone, estradiol 17 beta and thyroxine) during oestrous cycle in Barki ewes

Ezzo, O.H.; Shalash, M.R.; Hassan, S.G.; Afifey, M.M.; Youness, A.A.

Egyptian Journal of Veterinary Science( 1992); 27: 25-36


Accession: 002488108

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The concentrations of progesterone and oestradiol-17 beta were measured by radioimmunoassay and those of thyroid hormones by enzyme immunoassay in blood samples collected at intervals of 1-2 days from 27 cycling Barki ewes, run with teaser rams. Blood progesterone concentration ranged from 0.47-0.92 ng/ml on days 0-3 of the cycle to 5.39 ng on days 9-14, and although no ewes showed signs of oestrus in summer, the average blood progesterone concentration at the end of summer was 0.80 ng/ml. The blood oestradiol concentration was lowest on days 4-14 and peaked on day 0 and days 15-19, and that of thyroxine was higher during oestrus than at other times of the cycle. Season had a significant effect on the concentrations of progesterone and thyroid hormones.