SUMMARY
Sixty-eight multiparous Syrian does were randomly assigned to four
hormonal regimes. Those were (1) untreated control, (2) applying controlled
internal drug releasing device (CIDR) for 17 days to synchronize does, (3)
applying CIDR for 17 days + injecting 600 i.u. of pregnant mare serum
gonadotropine (PMSG) at withdrawal time and (4) applying CIDR for 17
days + injecting 600 i.u. of PMSG and 15 mg of prostaglandin (PGF2).
All synchronized does were artificially inseminated (AI) about 56 hours
post CIDR removal. The untreated control does were also artificially
inseminated at the same time like the other treated does. Semen used in AI
was collected from three tested mature bucks. Ejaculates from those bucks
were pooled and extended using IMV goat dilution. For each insemination,
a volume of one ml containing approximately 100 million motile
spermatozoa was used. Conception rates and kidding rates were recorded.
Does in treatments 3 and 4 showed estrus approximately 36 hours
post CIDR removal and were 8 hours earlier than those in treatments 1 and
2. Differences in pregnancy rates and number of newborns between the four
treatments were significant (P<0.05). Percentages of does kidded were
11.8%, 35.3%, 58.8% and 76.5% in treatments 1, 2, 3, and 4, respectively,
while multiple births percentages were 0.0%, 11.8%, 52.9% and 47.1% per
doe kidded in the respective treatments. Injecting does with PMSG and/or
PGF2 in treatments 3 and/or 4 at the time of pessary withdrawal was
associated with fruitful improvements in the kidding rate. The kidding
period in all hormonal-treated does was short (about 9 days) and this is an
advantage for synchronizing the estrus in Syrian does.