ABSTRACT
Twenty adult Ossimi ewes were used to study the effect of premating oxytocin Intramuscular
injection (IM) on some reproductive traits. They divided randomly into equal two groups.
Ewes in both groups were IM injected by 1ml GnRH (1st inj.) at day 0 (GnRH analogue contained
0.004 mg Bussrelin (Receptal. Intrvet, International BV Boxmeer-Holland). Then at day 7, they
injected (IM) by 0.7ml PGF2α analogue (Estrumate, Coopers Animal Health LTD, Berkhamsted-
England). Each ml of Estrumate contained 250 μg Cloprostenol Acetate. Then, ewes injected the
second GnRH dose (1 ml analogue) at day 9, two days post PGF2α injection. Oxytocin (20 I.U/IM ,
Adwia Company) was only IM injected to each ewe in the first group immediately pre-mating, one
day after the second injection with GnRH. Another oxytocin injection was given 12 hr. post the first
injection, after pre-second mating by the same rams. Ewes of the second group (control) were not
injected oxytocin premating by the same rams, one day after GnRH second injection.
Results showed improvement in most reproductive traits of oxytocin injected ewes. The
percentages of improvement were 33.33% for estrus rate, non-return rate and lambing, 25% for
twining rate, 8.67% for litter size and 44.44% for fecundity, compared to the control group. P4
concentration was high (P<0.05) in treated group affected by oxytocin injection. Thereafter, P4
decreased in all treated groups after PGF2α injection. Post-2nd GnRH injection, P4 levels showed a
pronounced increase in all treated groups. At day 20 post-mating, P4 levels showed the highest values
in both groups. It could conclude that premating oxytocin Intra-muscular injection could use to
improve reproductive performance of Ossimi ewes.