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The Development and Application of the Modern Reproductive Technologies to Horse Breeding 总被引：5，自引：0，他引：5
WR Allen 《Reproduction in domestic animals》2005,40(4):310-329
Although the horse was probably the first animal to experience and benefit from artificial insemination, it trailed the field somewhat with regard to the application of embryo transfer and other oocyte and embryo-related modern breeding technologies. But with a late run it is now back in mid-field and gaining fast on the other large domestic species in the application of the many technological advances of the past 20 years to sound breeding practice. Improvements in extenders and cryoprotectants have resulted in a veritable upsurge in the transport and insemination of cooled and frozen stallion semen, and parallel improvements in ovulation induction and synchrony, exogenous gonadotrophic stimulation of multiple fertile ovulations and simplified, more efficient methods for non-surgical transfer of embryos to recipient mares, coupled with relaxation of breed society registration restrictions, have together contributed to a similar upsurge in the application of embryo transfer to all breeds and athletic types of horses worldwide, with the continuing and notable exception of the Thoroughbred. Although conventional in vitro fertilization remains something of an unjumped fence in equids, other modern breeding technologies like hysteroscopic low-dose insemination, fluorescence-activated sex sorting of stallion spermatozoa, between-species embryo transfer, embryo freezing and bisection, transvaginal ultrasound-guided oocyte collection, intracytoplasmic sperm injection for fertilization (ICSI), gamete intrafallopian transfer (GIFT) and now nuclear transfer (cloning), have all been applied to equids with encouraging success. Cloning, especially, holds enormous promise for the Sporthorse industry to re-create champion geldings in stallion form for breeding purposes. 相似文献
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Polyclonal antisera for vascular endothelial growth factor (VEGF) and its two main receptor molecules, VEGF-I (Flt) and VEGF-II (KDR), were used in a conventional immunocytochemical staining method to localize these angiogenic ligand molecules in the endometrium and placenta of the mare during the oestrous cycle and pregnancy. The anti-VEGF and anti-Flt sera both labelled the lumenal and glandular epithelia of the endometrium throughout the oestrous cycle and both the invasive trophoblast cells of the endometrial cups and the non-invasive trophoblast of the allantochorion in pregnancy. The anti-KDR serum likewise stained the maternal and foetal epithelial layers during the oestrous cycle and pregnancy and it also labelled fibroblast-like cells in the endometrial and allantoic stromas and the endothelium of foetal and maternal capillaries. The results demonstrated that constant supplies of the principal vasculogenic and angiogenic factor, VEGF, and its two major receptors, Flt and KDR, are available on both the maternal and foetal sides of the placental barrier throughout gestation in the mare. They are presumed to facilitate the continuing development of the extensive foetal and maternal capillary networks that are such prominent features within the microplacentomes of the diffuse, epitheliochorial equine placenta. 相似文献
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Verminous encephalomyelitis due to Angiostrongylus cantonensis larvae was diagnosed in 2 foals at necropsy. The principal clinical feature was tetraparesis, although history and neurological examination revealed progressive and multifocal neurological disease. At presentation, a tentative diagnosis of parasitic larval migration involving the central nervous system (CNS), presumably due to Strongylus vulgaris, was proposed. Dissection of the spinal cord in one case resulted in recovery of intact larvae of both sexes of A. cantonensis. In both foals, histopathology of the brain and spinal cord revealed nematode sections which were consistent with A. cantonensis larvae. 相似文献
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An Overview of Low Dose Insemination in the Mare 总被引：1，自引：0，他引：1
The need for relatively high numbers of spermatozoa for artificial insemination limits our application of recently available technologies such as sex‐sorted semen. The fertility of two different methods of low dose insemination using fresh, frozen and sex‐sorted semen are compared in this overview. Satisfactory conception rates are described using very low doses of spermatozoa inseminated by either hysteroscopic or deep uterine insemination methods, proving the stallion is fully fertile. The hysteroscopic method appears to give higher conception rates when inseminating fewer than 5 × 106 spermatozoa and is therefore, the preferred method of insemination for sex‐sorted spermatozoa. However, hysteroscopic deposition of low numbers of spermatozoa from infertile stallions does not appear to improve their fertility. 相似文献
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Deciphering the effects of disperser assemblages and seed mass on patterns of seed dispersal in a rodent community 
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下载免费PDF全文 The sizes of both seed dispersers and seeds are traits that are likely to interact to influence seed fate in many synzoochoric plant species. Here, we examined whether members of a granivorous rodent community consisting of species of different body size vary in their effectiveness as seed dispersers, and how this relationship may be altered by seed size. We marked northern red oak (Quercus rubra) acorns with plastic tags and placed them in size‐selective rodent exclosures. The exclosures allowed differential access of rodent groups based on different body size: (i) small (e.g. Peromyscus spp.); (ii) small and medium (e.g. Tamias striatus); and (iii) small, medium and large (e.g. Sciurus carolinensis) species of rodents. Acorn removal did not differ among exclosure types, but more seeds were missing when removed by small rodents, probably because of larderhoarding. The treatments did not influence the relative frequency of acorn consumption. However, small rodents cached considerably fewer and partially ate more acorns than the other 2 groups. The mean dispersal distance was the longest for cages with medium openings, intermediate for cages with large openings and the shortest for cages with small openings. Acorn mass positively affected the probability of caching and this relationship was unaffected by exclosure type. In conclusion, granivorous rodents of different body sizes strongly differed in their interactions with acorns, with small rodents acting primarily as acorn predators and medium and large species contributing significantly more to dispersal of red oaks. 相似文献
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The small eccentricity of Neptune may be a direct consequence of apsidal wave interaction with the trans-Neptune population of debris called the Kuiper belt. The Kuiper belt is subject to resonant perturbations from Neptune, so that the transport of angular momentum by density waves can result in orbital evolution of Neptune as well as changes in the structure of the Kuiper belt. In particular, for a belt eroded out to the vicinity of Neptune's 2:1 resonance at about 48 astronomical units, Neptune's eccentricity can damp to its current value over the age of the solar system if the belt contains slightly more than an earth mass of material out to about 75 astronomical units. 相似文献
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F Camillo I Vannozzi A Rota B Di Luzio S Romagnoli G Aria WR Allen 《Reproduction in domestic animals》2003,38(5):380-385
Mules, hybrids resulting from the mating of a horse mare (Equus caballus, 2n = 64) to a Jack donkey (E. asinus, 2n = 62), are generally infertile. Five horse embryos were transferred non‐surgically to two cyclic and one acyclic recipient mules. In the mares and cycling mules, oestrus and ovulation were induced with, respectively, d ‐cloprostenol and human chorionic gonadotrophin (hCG). The acyclic mule, on the other hand, received oestradiol benzoate when the embryo donor was showing oestrus and progesterone after the donor had ovulated and until pregnancy diagnosis. Non‐surgical embryo collections were attempted on day 7 after ovulation and recovered embryos were transferred transcervically into the mules’ uteri. Mules that became pregnant were blood sampled serially for equine chorion gonadotrophin (eCG), progestagen and total conjugated oestrogen concentrations until around 6 months of gestation. The three embryos transferred to the acyclic mule did not produce any pregnancies whereas both embryos transferred to the cycling mules resulted in the birth of live foals. The peak concentration and duration of secretion of eCG differed markedly between the two pregnant mules, although both animals appeared to develop secondary corpora lutea beyond day 40 of gestation, as in normal intraspecies horse pregnancy. Moreover, the rise in serum oestrogen concentrations from around day 90 was also similar to that seen in normal pregnant mares. Parturition occurred spontaneously on day 348 of gestation in both mules and the resulting colt foals developed normally to weaning. Thus, cycling mules can carry a horse conceptus after non‐surgical embryo transfer and give birth to a normal mature foal. 相似文献