Comparative study between long and short term estrous synchronization protocols on estrous and fertility responses of cyclic ewes

الملخص EN

The present study was undertaken to minimize the period over which the progesterone impregnated sponges used for estrous synchronization protocols from 12 days to only 7 days, for improving conception rate and assess the serum hormonal concentrations, protein profile changes as well as oxidant- antioxidant status to compare short term with long term protocol in cyclic Barki ewes.

twenty multiparous cycling ewes (2-4) years old) were randomly assigned into two equal groups (10 each), the first group was the short term protocol group (s-term protocol) and treated with sponges containing 50 mg medroxy progesterone acetate(map) for 7days.

the second group was the long term protocol group (l-term protocol), also treated with the same sponges but for 12 days.

at the time of sponge withdrawal, all ewes were intramuscularly injected with200 iu pmsg (pregnant mare serum gonadotropin).

four fertile rams were introduced to all the ewes in the two groups for estrus detection and natural mating on the day of sponge withdrawal.

blood samples were collected on day of sponge insertion; on the 4th day, the 6th day of insertion; on the day of sponge withdrawal; on the 2nd day of withdrawal as well as at one month after withdrawal from both groups.

conception rate as well as lambing rate were significantly higher (p>0.05) in s-term protocol (90%) than in l-term protocol group (60%).

serum progesterone level was significantly (p<0.05) higher in s-term protocol than l-term protocol group on day of withdrawal and during the first month after withdrawal (1.97 ± 0.08 vs 1.34 ± 0.10 ng/ml) and (2.78 ± 0.15 vs 1.89 ± 0.17 ng/ml), respectively.

there was a significant decrease (p>0.05) in mda level on the 2nd day of withdrawal and at one month after withdrawal in s-term protocol ewes than lterm protocol (10.17± 0.25, 9.02± 0.22 and 12.45±0.54, 9.75±0.22 nmol\ml)), respectively.

short-term progestagen protocol (7 days) for estrus synchronization resulted in an improved fertility than the common long-term protocol (12 days) in adult cyclic ewes.