Publications (2)2.91 Total impact
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Article: Micromanipulation of equine embryos to produce monozygotic twins
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ABSTRACT: The uteri of Welsh Pony donor mares were flushed non surgically late on Day 5 after ovulation (at 18.00 h or midnight) or on Day 6 (between 06.00 h and 12.00 h) to recover morulae or early blastocysts. Twenty-six embryos were recovered from 63 flushing attempts (41 per cent). To investigate the effects of in vitro culture and micromanipulation on the development of the acellular equine blastocyst capsule, intact and manipulated embryos were cultured for varying times before being fixed and stained for histological examination. The capsule developed normally on two non-manipulated morulae and one blastocyst cultured for 12 to 48 h. However, no development or redevelopment of the capsule occurred during 48 to 96 h in culture of the 18 demi-embryos which resulted from the bisection of two morulae and seven blastocysts. The remaining 14 embryos were also bisected and the demi-embryos transferred surgically to synchronised recipient mares within 4 h. All eight pregnancies which developed, including two sets of monozygotic twins, originated from bisected morulae. No pregnancies developed following transfer of bisected blastocysts.Equine Veterinary Journal 06/2010; 21(S8):126 - 128. · 1.46 Impact Factor -
Article: Use of serial progesterone measurements to assess cycle length, time of ovulation and timing of uterine flushes in order to recover equine morulae
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ABSTRACT: In 1987, as part of an embryo transfer programme to produce monozygotic twin foals, mares were flushed during the morning (09:30 to 13:30 h) of Day 6. Of 100 flushes, 48 embryos were recovered half of which were morulae. In 1988, in an attempt to increase the proportion of morulae, various flushing times between 17.00 h on Day 5 and the afternoon of Day 6 were used. For flushes carried out during the morning of Day 6, recovery rates were similar to those of the previous year. However, although the proportion of flushes resulting in the recovery of morulae was not significantly different for times between 23:00 h on Day 5 and 13:00 h on Day 6, the overall recovery rates for flushes on Day 6 were higher than those on Day 5. In addition, a number of mares that did not produce an embryo when flushed before 09:00 h on Day 6, were subsequently found to be pregnant when scanned at Day 18 suggesting that flushing had been carried out before arrival of the embryo in the uterus. To determine whether valid predictions could be made as to when to flush a mare to maximise recovery of morulae, a review of embryo recovery rates and plasma progesterone profiles of a large herd of mares over two breeding seasons was carried out. Mean plasma progesterone levels on the first three days after ovulation were higher for mares that produced embryos when flushed on Day 5 than for all other groups. Comparison of the results of previous flushes with the corresponding plasma progesterone profiles suggested that the characteristics of the post ovulation progesterone rise may have some value in deciding when a mare should be flushed. A review of the effects of uterine flushing, PGF2α and hCG on cycle length and ovulation time was also carried out in order to devise more efficient methods of herd management and ensure a supply of suitably synchronised recipient and donor mares at convenient times for embryo transfer experiments.Equine Veterinary Journal 06/2010; 21(S8):10 - 13. · 1.46 Impact Factor
