bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stable isotope analysis: modelling lipid normalization for muscle and eggs from arctic mammals and birds
Authors: Ehrich Dorothée , Tarroux Arnaud , Stien Jenny , Lecomte Nicolas , Killengreen Siw , Berteaux Dominique , Yoccoz Nigel G. 
Published: June 2010

Summary1. Lipids are more depleted in 13C than proteins. Variable lipid contents in tissues affect therefore the measurements of stable carbon isotope ratios. Model based (also called mathematical) normalization has been suggested to correct δ13C values using the ratio of carbon to nitrogen (C/N) as a proxy for lipid content. This approach has not been thoroughly validated for terrestrial animals and it is not clear to what extent it is generally applicable or species/tissue specific.2. Ratios of stable carbon isotopes (δ13C) were obtained for muscle samples of 22 mainly terrestrial arctic mammal and bird species and for egg samples of 32 bird species from nine sites in the circumpolar Arctic. We used linear and nonlinear equations to model the difference in δ13C between samples from which lipids had been extracted chemically and bulk tissue samples. Models were compared on the basis of a model selection criterion (AIC) and of prediction error as estimated by cross‐validation.3. For muscle samples, a linear and a nonlinear equation performed equally well. The observed values were also well predicted by a previously published general equation for aquatic organisms. For egg samples, a nonlinear equation fitted separately to waterfowl and non waterfowl bird species fitted the data best. Prediction errors were, however, larger than for muscle samples.4. The generality of the inferred normalization equations was assessed by applying them to a second data set from a similar ecosystem, but produced in the frame of another study. The predicted lean δ13C values were within 0·5‰ of the observed values for 73% of the muscle samples, but only for 27% of the egg samples.5. Based on our results, we recommend model based normalization of δ13C values as an economic way to deal with varying lipid contents in muscle samples of mammals and birds. For egg samples, on the contrary, model based predictions had large errors. Therefore, we recommend chemical lipid extraction in order to estimate lipid‐free δ13C values for egg content.
Recent attempts to improve synchronisation of ovulation and to induce superovulation in the mare
Authors: PALMER E. 
Published: June 2010

SummaryRecent experiments designed to improve synchronisation and stimulation of ovulation in mares are described. The addition of daily injections of oestradiol benzoate to a routine synchronisation protocol, that utilised intravaginal sponge administration of a progestogen, ally I trenbolone, for seven days followed by an injection of prostaglandin at the time of sponge removal, reduced pituitary follicle stimulation hormone (FSH) secretion during treatment, increased the interval from sponge removal to ovulation but did not improve synchronisation of ovulation. Addition of daily injections of testosterone to the protocol reduced the secretion of pituitary luteinising hormone (LH), but not FSH, during treatment and it did improve synchronisation of ovulation.Attempts to stimulate follicular growth with an anti‐oestrogen, tamoxifen, during late anoestrus or after synchronisation treatment during the breeding season were unsuccessful; FSH and LH secretion rates and follicular growth were not stimulated. Treatment of mares with an extract of horse pituitary glands during successive oestrous cycles to give a total of six treatments per mare during the breeding season induced the growth of a mean of 3.3 mature follicles but only a mean of 1.8 ovulations in each treated cycle. This treatment regime did not seem to exhaust the pool of follicles that can be stimulated in subsequent cycles.
Dynamic physical interactions between the equine embryo and uterus
Authors: GINTHER O. J. 
Published: June 2010

SummaryRepealed examinations of mares with real‐time ultrasound echography demonstrated that the well‐known phenomenon of transuterine migration of the equine conceptus is not a simple one‐way passage. Instead, the embryonic vesicle was shown to bypass its eventual site of attachment many times per day while traversing the full length of each uterine horn and the uterine body.The embryonic vesicle showed limited mobility on Days 9 and 10 post ovulation when it spent more than 60 per cent of the time in the uterine body. Maximum mobility occurred on Days 11 to 14. Location changes within a uterine horn were more likely to be progressive when the vesicle was moving in a caudal direction, whereas location changes within the body were more likely to be progressive when the vesicle was moving in a cranial direction. Individuals of twin conceptuses had mobility patterns similar to those of singletons. Administration of a sympathomimetic blocking agent reduced the extent of mobility, indicating that uterine contractions are the propulsive force for vesicle mobility. Water‐filled balloons acting as simulated vesicles were also mobile when placed in the uterus on Days 12 or 13 of dioestrus, but their rate of movement was less than that of embryonic vesicles. It is suggested that the mobility of the embryonic vesicle may play a role in blocking the uterine luteolytic mechanism.Cessation of vesicle mobility (fixation) occurred on Day 15, 16 or 17 and it remained firm with no further movement between horns. Twin embryos exhibited a preference for unilateral fixation (70 per cent). Fixation may be a function of expansion of the embryonic vesicle combined with intraluminal resistance to mobility resulting from increasing uterine tone. The site of fixation was in the caudal portion of one of the horns, perhaps because of the curvature of the horns at that point. The concept of extensive mobility of the equine conceptus provides rationale for the development of hypotheses concerning the perplexing effects of reproductive status on the site of fixation and the consistency of fixation of the vesicle in the caudal portion of a uterine horn.Orientation is defined as rotation of the vesicle so that the embryonic pole is located ventrally, opposite the mesometrial attachment of the uterus. It is proposed that orientation takes place between the day of fixation and Day 19 when the embryo proper is first detectable by ultrasound. Orientation is attributable to disproportionate encroachment of the dorsal uterine wall, a massaging action by uterine contractions and greater thickness of the vesicle wall at the embryonic pole.
Between‐species transfer of horse and donkey embryos: A valuable research tool
Authors: ALLEN W. R. , KYDD JULIA , BOYLE M. S. , ANTCZAK D. F. 
Published: June 2010

SummaryDuring the six year period between 1979 and 1984 attempts to recover embryos non‐surgically at Days 6 to 8 after ovulation (Day 0) were successful on 15 of 30 occasions (50 per cent) from mated pony mares and on 112 of 210 occasions (53 per cent) from mated or artificially inseminated jenny donkeys. Surgical transfer of nine horse embryos to jenny donkeys and 95 donkey embryos to pony mares resulted in five horse‐in‐donkey and 64 donkey‐in‐horse pregnancies (56 and 67 per cent, respectively).The striking differences in placentation and hormone secretion patterns that exist between these two types of extraspecific equine pregnancy make them ideal models to study foetomaternal interactions during pregnancy and immunological aspects of early foetal death. Donkeys appear able to carry horse foetuses to term, perhaps because of normal endometrial cup development and the resulting high secretion rates of equine chorionic gonadotrophin (eCG) and progesterone. Conversely, endometrial cups fail to develop in horses carrying donkey foetuses, the great majority of which grow normally to Day 70 of gestation but thereafter succumb to a vigorous maternal cell‐mediated reaction directed against the donkey allantochorion.Administration to mares carrying donkey conceptuses of: (a) Synthetic progestogen; (b) a partially purified extract of eCG; (c) large volumes of pregnant and non‐pregnant mares' serum; and (d) repeated injections of lymphocytes from the genetic donkey sire and dam of the embryo, resulted in a significant improvement in pregnancy survival only in those mares treated with pregnant mares' serum and parental donkey lymphocytes. The hypothesis is therefore advanced that failure of the untreated donkey‐in‐horse pregnancy results from the absence of the normal antigenic stimulation of the maternal immune system to provide immunoprotection for the foreign conceptus. In all other types of intra‐, inter‐ and extraspecies equine pregnancy this occurs during invasion of the maternal endometrium by the specialised foetal trophoblast cells to form endometrial cups.
Immunological aspects of pregnancy in mules
Authors: ANTCZAK D. F. , DAVIES C. J. , KYDD JULIA , ALLEN W. R. 
Published: June 2010

SummaryThe pregnant mare makes a range of immune responses to paternally‐inherited foetal histocompatibility antigens. Cytotoxic antibody is first detected in major histocompatibility complex (MHC)‐incompatible pregnancies by Days 50 to 70 of gestation. This follows shortly after the development of the endometrial cups and is concurrent with a striking accumulation of maternal lymphocytes and other mononuclear cells in the endometrial stroma around each cup. No such cellular infiltration occurs at the endometrium‐allantochorion border.The temporal coincidence between endometrial cup formation, cytotoxic alloantibody production and the accumulation of maternal lymphocytes suggests that these three events are interrelated. The relationships have been explored using immunogenetic markers in intraspecies horse pregnancy, by comparing immunological and endocrinological aspects of pregnancy in mares and jenny donkeys carrying normal intra‐specific and interspecific hybrid conceptuses and, finally, by examining foetomaternal interactions in sterile interspecies mules carrying pregnancies of both parental types created by embryo transfer. The working hypothesis has been that the endometrial cups are the source of immunogenic foetal histocompatibility antigen in equine pregnancy and that the cytotoxic antibody response and the lymphocyte accumulation around the cups represent humoral and cell‐mediated arms of the maternal immune response.Establishment of MHC‐compatible pregnancies demonstrated no significant effect of MHC differences between mother and foetus on serum equine chorionic gonadotrophin (eCG) levels, the duration of eCG secretion or the magnitude of the maternal leucocyte accumulation around the cups. Comparison of intraspecies horse and donkey pregnancies showed major differences between the two, including lower serum eCG levels, smaller endometrial cups with reduced leucocyte accumulation and a lower incidence of maternal sensitisation to foetal histocompatibility antigens in donkey pregnancy. Examination of interspecies mule and hinny pregnancies, on the other hand, showed a marked increase in the maternal lymphocyte reaction around the endometrial cups and a definite influence of the paternal genome of the foetus on eCG production.The successful transfer of horse and donkey embryos to female mules demonstrated that: (a) Both horse and donkey conceptuses express histocompatibility antigen in immunogenic form early in pregnancy; (b) both horse and donkey chorionic girdle cells can invade the endometrium of the mule to form endometrial cups, the eCG production rate of which is dependant upon foetal genotype; and (c) the magnitude of the lymphocyte accumulation around the endometrial cups does not correlate with known genetic differences between mother and foetus.
Transfer of exotic equine embryos to domestic horses and donkeys
Authors: KYDD JULIA , BOYLE M. S. , ALLEN W. R. , SHEPHARD ALISON , SUMMERS P. M. 
Published: June 2010

SummaryA total of 43 non‐surgical embryo recoveries performed on two Przewalski's horse mares(Equus przewalski)and two Grant's zebra mares(E burchelli)yielded 11 Przewalski and 14 zebra embryos. Surgical transfer of nine Przewalski embryos to domestic pony recipient mares resulted in seven (78 per cent) extraspecific pregnancies. Two of these recipient mares gave birth to live foals on Days 324 and 329 of gestation respectively and two are at Days 175 and 166 respectively at the time of writing; three conceptuses were resorbed at various times between Days 20 and 100. Non‐surgical transfer of two Przewalski's horse embryos and flank surgical transfer of one other Przewalski's horse embryo to domestic mares failed to establish any pregnancy.Surgical transfer of five zebra embryos to domestic pony recipients resulted in three (60 per cent) extraspecific pregnancies; one conceptus was resorbed between Days 61 and 70 and the other two are at Days 190 and 201 respectively at the time of writing. Surgical transfer of seven zebra embryos to jenny donkeys gave two (29 per cent) extraspecific pregnancies; one conceptus was resorbed between Days 53 and 79 and the other foal was born prematurely on Day 292 and lived for only 3 h. Non‐surgical transfer of one Day 10 zebra embryo to a jenny donkey did not result in a pregnancy.These experiments demonstrated that it is possible repeatedly to recover embryos non‐surgically from sedated wild equids and transfer them successfully to domestic horse and donkey recipients. The production of such extraspecific pregnancies by embryo transfer has considerable value as a research tool and the technique should also prove valuable in the future for maximising the reproductive potential of endangered equine species in captivity.
Current developments in embryo transfer
Authors: PASHEN R. L. 
Published: June 2010

SummaryThe present state of knowledge about embryo transfer and the techniques used in recovering, manipulating and sexing embryos are discussed. Speculation is made about possible future developments, including gene injection and application of recombinant DNA technology. It is concluded that such studies will open up new developments in animal breeding. The end result, however, will still depend on an embryo being transferred to a recipient to carry the pregnancy to term.
Factors affecting success of equine embryo transfer
Authors: SQUIRES E. L. , GARCIA R. H. , GINTHER O. J. 
Published: June 2010

SummaryThe production of a live foal via embryo transfer is dependent upon collection of a viable embryo, transfer of the embryo into an appropriate recipient and successful establishment and maintenance of a pregnancy within the recipient. Several factors have been identified that affect embryo recovery. These include age of embryo, reproductive status of the donor and number of detected ovulations. Pregnancy rates have been shown to be influenced by the method of transfer, the technician involved, the time of year, the age and size of embryo and the synchrony of donor and recipient. Data on each of these factors as they affect embryo recovery and transfer are presented and discussed.
Bony fragments in the tarsocrural and metacarpo‐ or metatarsophalangeal joints in the Standardbred horse‐a radiographic survey
Authors: SANDGREN B. 
Published: June 2010

SummaryRadiographic examination of the tarsocrural, metacarpo‐ or metatarsophalangeal joints was made in 139 Standardbred horses. Most were under three years old with no history of orthopaedic problems. In the tarsocrural joint, osteochondrosis was observed in 25 (18.1 per cent) of the horses (n=138) and 14 (56 per cent) of these were affected bilaterally. In the metatarsophalangeal joint, the most frequent radiographic abnormality was single or multiple bony fragments or defects at the plantar proximal end of the proximal phalanx, which was noticed in 40 (28.8 per cent) of the horses (n=139). The lesion was much more frequent in the hind than in the forelimbs. Ten per cent of horses affected in the hindlimbs had the lesions bilaterally. Palmar or plantar fragments were also more common in the medial, than the lateral, part of the joint. With regard to osteochondrosis in the tarsocrural joint and palmar or plantar bony fragments in the metacarpo‐ or metatarsophalangeal joints, no significant differences in incidence were found between sexes or between left and right sides. There was no correlation between findings of osteochondrosis in the tarsocrural joints and the occurrence of bony fragments in the plantar part of the metatarsophalangeal joints. In the forelimbs, bony fragments in the dorsal parts of the metacarpophalangeal joint were noticed in three (2.9 per cent) of the horses (n=103) and the corresponding figure for the metatarsophalangeal joint was three (2.2 per cent) (n=139). In 102 horses, the tarsocrural, the metacarpo‐ and the metatarsophalangeal joints were radiographed at the same time. One or several joints were affected with osteochondrosis, bony fragments, or defects in underlying bones in 45 (44.1 per cent) of these horses.
The hock as a potential site for non‐invasive bone measurement
Authors: SCOTTI E. , JEFFCOTT L. B. 
Published: June 2010

SummaryAn in vitro study on the calcaneus of adult horses (n = 5) and foals (n = 10) was carried out using radiographic photodensitometry, single photon absorptiometry, transmission ultrasound velocity and chemical analysis. Data for trabecular bone content, ash, calcium and phosphorus levels were obtained. As techniques for assessing bone quality, ultrasound velocity was not sufficiently sensitive nor accurate and radiographic photodensitometry was found to be of limited value. Photon absorptiometry was both accurate and reproducible, although some variation in bone mineral content and bone mineral density was observed along the length of the calcaneus. Bone mineral content was estimated in a second series of fibular tarsal bones from 23 horses ranging in age from less than six months to 16 years. The photon absorptiometry technique was also applied to the hocks of four hind limbs at post mortem and two horses under general anaesthesia. It was concluded that the calcaneus was a feasible site for photon absorptiometry, but that the present equipment would require considerable modification for use in the standing horse.
Evaluation of equine locomotion during different degrees of experimentally induced lameness I: Lameness model and quantification of ground reaction force patterns of the limbs
Authors: MERKENS H. W. , SCHAMHARDT H. C. 
Published: June 2010

SummaryForce plate data from walking horses were used to evaluate the locomotion of a group of six horses during experimentally induced lameness in a forelimb or a hindlimb. By tightening or loosening screws in modified horseshoes the resulting pressure pain on the sole enabled induction and release of three different degrees of supporting lameness within a period of 2 h. The ground reaction force (GRF) patterns of the different recording sessions were compared with control data of the same horse as well as with the ‘standard’ horse data using a quantitative evaluation procedure involving 93 GRF parameters. Clinically mild and moderate lameness at the walk could be distinguished by applying the H(orse)INDEX method, using ‘standard’ GRF data of horses of the same breed. Even subtle changes (clinically mild lameness at the trot but no lameness visible at the walk, and nerve blocking of moderate lameness at the walk) could be demonstrated objectively using an adapted quantification procedure (the C(ontrol)INDEX method), if control GRF parameters of that horse were obtained before lameness was present.
Curettage of subchondral bone cysts in medial femoral condyles of the horse
Authors: WHITE N. A. , McILWRAITH C. W. , ALLEN D. 
Published: June 2010

SummaryFifty one horses had unilateral or bilateral femorotibial arthrotomy with medial condyle bone cyst curettage. A total of 60 cyst were treated. Treated horses responded to the surgery three to 12 months postoperatively. In 42 horses lameness was reduced or eliminated, enabling them to return to and remain in their intended function. Of these 42 horses 35 are sound, four of which have not started training, and seven showed partial improvement, two of which had no long term follow up. Of the remaining nine horses, two showed no reduction in lameness and seven were not followed up. Arthrotomy was successful in reducing or eliminating lameness in 82 per cent of all horses and 95 per cent of those where follow‐up was possible (42 of 44). Arthrotomy with subchondral bone cyst enucleation and curettage was determined to be a satisfactory treatment in anticipation of a variety of athletic activities.
Luteal maintenance in mares after transfer of equine trophoblastic vesicles
Authors: BALL B. A. , ALTSCHUL M. , HILLMAN R. B. 
Published: June 2010

SummaryTrophoblastic vesicles have been used to study maternal recognition of pregnancy in several domestic species. Because of the unique aspects of pregnancy recognition in mares, this study was conducted to examine the ability of trophoblastic vesicles from Day 12 to 14 equine conceptuses to prolong luteal maintenance in mares. Trophoblastic vesicles formed in vitro from conceptus fragments were transferred surgically to the uterus of mares (n=15) at Days 6, 8 or 10 after ovulation. Sham‐operated mares (n=8) served as controls. Luteal maintenance was assessed by daily serum progesterone concentrations and by evaluation of interovulatory intervals. Interovulatory intervals were longer (p<0.1) in treated than in control mares (30.2 ± 2.6 vs. 22.6 ± 2.9, respectively). Trophoblastic vesicle transfer at Day 10 after ovulation resulted in more (P=0.16) treated than control mares with interovulatory intervals of at least 42 days (5 of 9 vs 0 of 3, respectively). Progesterone concentrations differed (p<0.05) between treated mares with prolonged interovulatory intervals, and control or treated mares without prolonged interovulatory intervals, by Day 14 or 15 after ovulation, respectively. Although luteal maintenance was prolonged in 56 per cent of the treated mares that received vesicles at Day 10, trophoblastic vesicles did not enlarge spherically in utero sufficiently for detection by transrectal ultrasonography.