ABSTRACT
Twenty adult Ossimi ewes were used to study the effect of premating oxytocin intra-muscular
(IM) injection on some reproductive traits. They were randomly divided into two equal groups.
Ewes in both groups were IM injected by 1 ml GnRH analogue (1st inj.) at day 0. Then at day 7,
they were IM injected by 0.7ml PGF2α analogue. A second GnRH dose (1 ml analogue) was given
at day 9, two days post PGF2α injection. Oxytocin (20 I.U) was IM injected to each ewe in the first
group immediately premating, one day after the second injection by GnRH. Another oxytocin
injection was given 12 hr. post the first one, pre-second mating by the same rams.
Results showed improvement in most reproductive traits of oxytocin injected ewes. The
percentages of improvement were 33.33% either for estrus rate, non-return rate or lambing rate,
25% for twinning rate, 8.67% for litter size and 44.44% for fecundity, compared to the control
group. P4 levels was the highest (P<0.05) in injected group by oxytocin. While, P4 decreased in
both groups after PGF2α injection. P4 concentration increased in both groups after the second
GnRH injection. At day 20 post-mating, P4 levels showed the highest values in both groups. It
could be concluded that premating oxytocin intra-muscular injection can be used to improve
reproductive performance of Ossimi ewes.