Status of estrus and blood serum estrogen and progesterone in Arabic ewes synchronized with CIDR in non-breeding season

Estrus synchronization is a valuable technique in control of reproductive function in ewe. The aim of this study was to determine the status of estrus incidence and hormone profiles in blood serum of Arabic ewes synchronized using the long and short periods of CIDR in non-breeding season. In non-breeding season, a total of 58 Arabic ewes aged 2-5 years old (average of BW 46 kg) and non pregnant in a completely randomized design were assigned to three experimental groups: 1- control (no treatment), 2- short-term (6 days) and 3- long-term (14 days) treatments with vaginal CIDR. Immediately after removing the CIDR, 600 IU of PMSG was injected intra muscle. In the CIDR treatments, estrogen and progesterone concentrations of blood serum were measured immediately before of CIDR insertion, three days after CIDR insertion, one day after CIDR removal and 50 days after mating. In order to heat detection and mating, one healthy and fertile Arabic ram was introduced to every 5 ewes. The interval to estrus after CIDR removal in short and long term treatments, were 51.02 and 34.74 hours, respectively (P<0.01). Occurrence of estrus in short-term (88.8%) and long term (95.2%) treatments of CIDR was higher than control (5.26%) (P<0.01), but this difference between CIDR treatments was not significant (P> 0.05). One day after CIDR removal and 50 days after mating, estrogen concentration of blood serum was significantly higher in long-term than the short-term CIDR treatment (P<0.01). There was no significant difference in blood serum progesterone level between treatments in all times (P>0.05). The concentrations of these hormones in various periods of short and long term treatments of CIDR were in fluctuant. The use of short term (6 days) CIDR has the appropriate estrus occurrence and reproductive function in non breeding season of Arabic ewes.