Effect of estrus synchronization protocols on the reproductive performance of Barki sheep

الملخص EN

The study aimed to determine the influence of estrus synchronization regimes on reproductive performance in Barki ewes.

Forty Barki ewes were randomly allocated into 2 equal groups (A & B).

Group A were treated with vaginal sponges impregnated with 25 mg medroxy-progesterone acetate (MAP).

On the day of sponge's withdrawal the ewes were reassigned according to eCG dose into three subgroups (A1, A2 and A3).

Group A1, served as control, without eCG injection, while groups A2 and A3 were injected IM with 300 and 500 IU/eCG, respectively.

The ewes of group B have received vaginal sponge containing 50 mg of MAP.

At the day of sponge removal, the ewes were subdivided into 3 subgroups B1, B2 and B3 and treated with eCG as subgroups A1, A2 and A3, respectively.

Three fertile rams were subjected to run with ewes for heat detection and natural mating.

Blood samples were taken from mated ewes on day 17 post mating, for determination the level of progesterone for pregnancy determination.

Results revealed that the incidence of estrus response were 74.60±9.71 and 79.37±9.71 for groups A (25 mg MAP) and B (50 mg MAP), respectively.

Irrespective to MAP sponge concentrations, the estrus response in ewes injected with 500 IU/eCG (A3B3) was higher (92.86±11.58%) than group A2B2 (71.43±11.58%) which treated with 300 IU/eCG and control group A1B1 without eCG (66.67±12.51%) with no significant differences.

The onset of estrus in ewes of group A was significantly shorter (P<0.05) than group B (36.23±3.18 h vs 46.10±3.41 h).

Regardless of MAP, the onset of estrus in control ewes (without eCG) was significantly longer (56.02±4.70 h; P<0.01) than ewes treated with 300 IU/eCG, (36.20±3.82 h) and 500 IU/eCG (31.27±3.49 h).

The means of estrus duration were similar with no significant effects of MAP and eCG doses.

No significant differences in the pregnancy rates between group A and B, whereas, the pregnancy rate was significantly higher in group A3B3 (92.86±11.21%) than groups A1B1 and A2B2 (50.00±14.24 and 80.00±12.74%, respectively).

Neither MAP nor eCG has been a significant effects on the lambing and fecundity rates.

In conclusion, Sponges containing 25mg MAP co-treated with 300-500 IU/eCG is suitable protocol for estrus synchronization and improve pregnancy rate in Barki ewes.