Anotace:
The hormonal protocol is used to increase reproductive efficiency in ewes. The aim of the study was to investigate the effects of two intervals of hormonal protocol (progesterone + equine chorionic gonadotropin (P4 + eCG)) for estrus synchronization in Awassi ewes. A total of 110 Awassi ewes were randomly divided into two groups. The first group (short term) (n = 45) used sponges for 7-day. The second group (long term) (n = 65) used sponges for a 14-day. At the time of sponge withdrawl, two doses of eCG injection were administrated intramuscularly (500; n = 54 and 1000 IU; n = 56) for each main group. All ewes were mated with ram following estrous sings. Transabdominal ultrasonography was used for pregnancy diagnosis on 35- and 40-days following mating. Percentage of estrus response, conception rate, fertility rate, prolificacy rate twinning rateand missing rate were calculated for each group. Estrus response, fertility rate, conception rate, and low missed rate was greater in high dose eCG comapred to low dose. Estrus response, fertility rate, conception rate, twinning rate, litter size was greater in high dose and short-term group (100%, 100%, 100%, 19.2, and 0%) comparted to other groups. The estrus response, fertility rate, conception rate, twinning rate, litter size was greater in high dose and short-term group comparted to other groups. In addition to that missed rate was the lowest on high dose and short-term group comparted to other groups. In conclusion, a short-term treatment (7 days) for the induction of estrus can be a good alternative to a traditional longer duration treatment (14 days). Short-term priming has the advantage of allowing more flexibility in the treatment protocol under field conditions.