Monitoring the ovarian activities in Sanjabi ewes using progesterone concentration assay

This experiment was conducted to identify the ovarian activity throughout the year and determine the length of estrus cycles of Sanjabi sheep. Accordingly, blood serum samples were collected weekly and daily (12th of September to 11th of November) from 14 non-pregnant Sanjabi ewes at Mehregan livestock research station in Kermanshah for one year and the progesterone concentration was measured using the radioimmunoassay. The daily evaluation of progesterone secretion proceeding showed that there were four estrus cycles during the period from September 11 to November 12. The average length of the first to fourth estrus cycles was 6.30±2.41, 8.33±1.90, 9.17±2.50, and 16.08±3.11 days, respectively, and the mean time interval between estrus cycles was 6.47±2.46 days. The highest progesterone concentration mean in 61.54 percent of ewes was observed in November and in 38.46 percent of ewes was observed in spring, especially in April. In total, 78.57, 78.57, 71.43 and 78.57 percent of the ewes in June, July, February, and March, respectively, were in perfect anestrus conditions, but all of the ewes had the active ovarian cycle in November. The average length of ovarian activities and in contrast perfect anestrus were estimated 215 ± 38 and 150 ± 48 days per year, respectively. The results showed that Sanjabi ewes had an active ovarian cycle about 60 percent of the time of the year; so, there is naturally applicable of a three-time lambing program in two years in this sheep.