Embryo transfer in sheep and goats: a review

Ishwar, A.K.; Memon, Mushtaq A.

doi:10.1016/0921-4488(95)00735-0

Cited by 53 publications

(69 citation statements)

References 40 publications

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“…Corpora lutea from ewes undergoing premature luteolysis have a reduced population of small luteal cells compared to normal corpora lutea (Schiewe et al, 1991). Subnormal luteal function is a result of the premature release of PGF 2a from the uterus because of the presence of endometrial oxytocin receptors, which in turn is up-regulated by high levels of oestradiol (Ishwar and Memon, 1996). The incidence of ewes with regressed corpora lutea seems to be related to excessive levels of oestrogen, bringing about luteolysis and to a lower endometrial concentration of progesterone receptors (which down-regulate oestrogen endometrial receptors expression in anestrous ewes (Robinson et al, 1991) than in normal cycles .…”

Section: Luteal Activitymentioning

confidence: 99%

Effect of exogenous melatonin on the ovary, the embryo and the establishment of pregnancy in sheep

Abecia¹,

Forcada²,

Casao³

et al. 2008

Animal

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Administration of melatonin to advance the breeding season in sheep has been widely used, since this hormone conveys the photoperiodic signal to the reproductive neuroendocrine axis. An increased lambing percentage has been reported following such treatment during anoestrus, which could be mediated through a higher rate of embryonic survival, either by an improvement in luteal function or by a reduction in the antiluteolytic mechanisms. The aim of this article is to review the body of knowledge on the effect of melatonin on the ovine ovary, the embryo and the establishment of pregnancy. Some studies using synchronized ewes have found that melatonin treatments during anoestrus do not improve ovulation rate by modifying the timing of follicle emergence, but increasing the number of ovulatory follicles by decreasing the atresia of medium and large follicles. On the other hand, the addition of melatonin to the in vitro maturation medium does not improve oocyte maturation rate in oocytes from sheep ovaries recovered either in anoestrus or in the breeding season. However, a luteotrophic effect of melatonin at either short or medium term has been reported. We have recently observed that melatonin implants tend to improve the survival of embryos collected from ewes after superovulation in anoestrus. More specifically, melatonin induced a significant reduction of the number and rate of non-viable (degenerate and retarded) embryos. Preliminary data from our laboratory suggest that the uterine sensitivity to progesterone -in terms of progesterone receptor expression -of superovulated ewes could be reduced by melatonin treatment. It can be concluded that the success of exogenous melatonin as a means to improve lamb production of sheep is due, at least in part, to an improvement of luteal support and embryonic survival.

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Section: Luteal Activitymentioning

confidence: 99%

Effect of exogenous melatonin on the ovary, the embryo and the establishment of pregnancy in sheep

Abecia¹,

Forcada²,

Casao³

et al. 2008

Animal

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“…This method does not only impose surgical trauma and formation of post-operative adhesions, but mostly limits the number of times surgical flushings may be performed on the same animal (Pereira et al, 1998;Suyadi et al, 2000). The alternative method of transcervical embryo collection in goats has been limited in the past because of the difficulty of passing the catheter through the cervix (Ishwar & Memon, 1996;Suyadi et al, 2000). Even after the discovery that by injecting animals with hormones such as oxytocin, oestrogen and prostaglandin, could ripen the cervix, this procedure is still limited by the number of flushings needed, as well as the time taken to flush one donor 194 Suyadi et at., 2000;Holtz, 2005).…”

Section: The South African Journal Of Animal Science Is Available Onlmentioning

confidence: 99%

Can repeated superovulation and embryo recovery in Boer goats limit donor participation in a MOET programme?

2010

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________________________________________________________________________________ AbstractThis study evaluated the effect of repeated superovulation and embryo recovery in 15 Boer goat does. Does were synchronised for oestrus using CIDR's for 17 days and superovulated with pFSH during the natural breeding season (autumn). Cervical inseminations with fresh undiluted semen were performed 36 h and 48 h following CIDR removal and the embryos surgically flushed six days after the second AI. Does superovulated for the first time recorded a shorter mean (± s.e.) induced duration of oestrus (20.8 ± 1.0 h), when compared to those repeatedly superovulated (30.4 ± 6.7 h). The mean (±s.e.) number of structures and embryos recovered were significantly lower in does treated repeatedly (6.0 ± 1.7 and 3.8 ± 1.7) than does superovulated for the first time (12.9 ± 0.5 and 11.7 ± 0.5), respectively. The mean (±s.e.) number of unfertilised ova per donor was significantly higher in repeatedly superovulated does (5.5 ± 1.6), compared to does superovulated for the first time (0.1 ± 0.1). The fertilisation rate and the number of transferable embryos were significantly lower in does treated repeatedly, compared to does superovulated for the first time. These results indicate that the number of times that a Boer goat doe can be utilised as the embryo donor may be limited to three times. _______________________________________________________________________

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“…Multiple Ovulation and Embryo Transfer (MOET) is a reproductive biotechnology in farming that is used in females of high genetic value, for the purpose of rapidly multiplying the number of their descendents, in a short time span, resulting in the genetic and productive enhancement of the herd (Ishwar & Memon, 1996). MOET is commercially used in sheep industry and depends on the surgical recovery of embryos, where the principal disadvantage is the limited number of times a female donor can be used (Naqvi et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Relaxant effect of the essential oil of Croton nepetifolius on ovine cervix

Pereira¹,

Melo²,

Morais³

et al. 2012

Rev. bras. farmacogn.

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Abstract:We investigated the in vitro effect of the essential oil of Croton nepetifolius Baill., Euphorbiaceae (EOCN), on spontaneous or induced contractions of circular and longitudinal muscles from the ovine cervix during the luteal phase of the estrous cycle. The relaxant effect of EOCN was expressed as a percentage of the contraction recorded before the addition of the oil and calculated relative to the preparations exposed only to the vehicle. The IC50 (concentration of oil required to produce a 50% maximal reduction in muscle contraction) for relaxation of spontaneous contractions in circular and longitudinal muscles was signifi cantly lower than the IC50 for blockade of K + -induced contraction (27.19 µg mL -1 versus 262.72 µg mL -1 and 40.92 µg mL -1 versus 222.47 µg mL -1 , respectively). Interestingly, there was a high degree of selectivity in the action of EOCN on cervix layers concerning the inhibition of acetylcholine-induced contraction in circular (IC50 277.10 µg mL -1 ) and longitudinal (IC50 52.56 µg mL -1 ) muscles. In conclusion, EOCN is able to relax ovine cervix during the luteal phase. This work opens the perspective of applying EOCN in ovine embryo transfer.

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Embryo transfer in sheep and goats: a review

Cited by 53 publications

References 40 publications

Effect of exogenous melatonin on the ovary, the embryo and the establishment of pregnancy in sheep

Effect of exogenous melatonin on the ovary, the embryo and the establishment of pregnancy in sheep

Can repeated superovulation and embryo recovery in Boer goats limit donor participation in a MOET programme?

Relaxant effect of the essential oil of Croton nepetifolius on ovine cervix

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