02503naa a2200229 a 450000100080000000500110000800800410001910000130006024501530007326000090022652018060023565000250204165000100206665000240207665000310210065300280213170000150215970000170217470000150219170000160220677300510222215309972011-11-04       2000    bl uuuu     u00u1 u    #d1 aBARI, F.  aEffect of mating system, flushing procedure, progesterone dose and donor ewe age on the yield and quality of embryos within a moet program in sheep.  c2000  aMultiple ovuIation and embryo transfer (MOET) has the potential to increase the rates of genetic improvement in sheep. However, better realization of this potential requires a higher yield of transferable embryos. This we investigated some factors that may contribute to high embryo yield and quality under field conditions, as part of an ongoing MOET program. Comparison of the effects of 2 breeding systems (natural service plus laparoscopic intrauterine AI vs natural service only) on embryo yield and quality indicated that while AI did not affect embryo recovery, it significantly (P&lt0.05) improved fertilization rate and embryo quality, and increased (P&lt0.05) embryo survival rate after transfer to recipients. Two flushing procedures (the original semi-Iaparoscopic and a modified version) were compared for effects on embryo recovery. The modifications made to the original collection method increased (P&lt0.001) embryo recovery from 69.0 + 2.4 to 83.2 + 0.6%. The effects of the progestagen priming dosage during superovuIatory treatment and ewe age on MOET outcome were also investigated. Donor ewes primed with 30-mg progestagen sponges came fito estrus 1.9 h earlier (P&lt0.05) than those primed with 45-mg sponges, but there was no difference in ovuIation rate or embryo recovery, or in embryo survival afier transfer between the 2 regimens. However, Chisquare analysis indicated a significant benefit in favor of the higher progesterone dose on both ferti1ization (P&lt0.01) and embryo quality (P&lt0.001). Age of donor ewe did not significantly affect the timing of estrus, fertilization rate or embryo survival afier transfer. While adult ewes had higher (P&lt0.05) ovulation rates and embryo yields, shearling ewes produced a much higher proportion of Grade 1 embryos (P&lt0.05).  aComportamento Sexual  aOvino  aReprodução Animal  aTransferência de Embrião  aSistema de acasalamento1 aKHALID, M.1 aHARESING, W.1 aMURRAY, A.1 aMERRELL, B.  tTheriogenologygv. 53, n. 3, p. 727-742, 2000.