Compare of The Short and Long Term Estrus Synchronization Protocols on Reproductive Performance of ewe

To evaluate effects of the short term (7 days) and long term (14 days) progesterone based estrus synchronization protocols on reproductive performance of ewes out of the breeding season (May of 2017), Lori ewes (n=60) were randomly assigned to one of two estrus synchronization treatments; The short term protocol consisted of a 7-day treatment with controlled internal drug release (CIDR) devices, administration of GnRH at CIDRs insertion on Day 0, and pregnancy mare serum gonadotropin (PMSG) and PGF2α at CIDRs removal on Day 7. The long term group as control treatment consisted of a 14-day treatment with CIDR devices and administration of PMSG at CIDRs removal on Day 14. Fertile rams were introduced into both groups at CIDRs removal. Induce estrus, Fertility, twining, litter size and fecundity were calculated. Data were analyzed in Chi- Square method by SAS 9.1. Estrus expression during first cycle in short and long term treatments was 95 and 100%, lambing rate was 70.00 and 63.33%, twining rate was 14.28 and 10.52%, litter size was 1.14 and 1.10 and fecundity rate was 0.80 and 0.70 respectively. Results shown that there was no significant difference between two estrus synchronization protocols in all of studied parameters in this breed. Therefore, it seems that to selection one of two treatments, researches should be perform about this two protocols in terms of economic expenses and practicality in this breed.

Keywords:

Ewe , CIDR , Fecundity , Twining