ABSTRACT
The influence of gonadotropin releasing hormone (GnRH), Pregnant Mare Serum
Gonadotropin (PMSG) and human Chronic Gonadotropin (hCG) on some reproductive responses of
Egyptian ewe lambs was evaluated. Twenty five animals (aged 8 – 12 months and weighed 27 - 33
Kg) were divided into 5 groups ( 5 ewe lambs each). Group (1) served as a control, Group (2),
received vaginal sponges impregnated with MAP (60 mg medroxy progesterone acetate) for 14 days,
during this period, animals fed 3 kg Berseem, (Trifolium alexandrinum) plus 500 gm concentrate /
head/ day. Group (3), received vaginal sponges impregnated with (60 mg, MAP) for 14 days, on the
day of sponge removal; each animal injected by PMSG (250 IU, I/M). Group (4) animals received
1.25 ml Receptal (0.5 μg, GnRH) I/M, on day 0, seven days later, ewe lambs injected with 0.5 ml
Estromate (125 μg. PGF2α) I/M, after 48 hours, animals treated with a second dose of GnRH. Group
(5) received two injections of (0.5 ml Estromate) at days 0 and 7, respectively, after 72 hours from the
second dose of PGF2α ewe lambs were injected 0.2 ml hCG. Heat detection was performed and transrectal
ultrasound scanning also performed to confirm estrus, pregnancy and follicular diameter. The
results revealed that, administration of PMSG (group 3) reduced the interval to estrus (the onset of
heat /hours) significantly (P< 0.01) compared with control and other groups. Regarding conception
and lambing rates, groups 2, 3, & 4 had affected significantly (P˂ 0.01) compared to groups 1 & 5.
Follicular diameter (mm) tended to increase significantly in treated groups than the control one.
Results suggest that, tested hormones have effect on selected reproductive responses of Egyptian ewe
lambs while administration of PMSG (Group 3) has the best response compared to other hormonal
treatments.