PubMed Health⌕ Search

Biomedical subjects

H Sieme

Publications and source records attributed to H Sieme.

At least 19 recordsLinked to original sources
PubMed2005

Genetic markers for stallion fertility--lessons from humans and mice.

Our knowledge on the many aspects of mammalian reproduction in general and equine reproduction in particular has greatly increased during the last 15 years. Advances in the understanding of the physiology, cell biology, and biochemistry of reproduction have facilitated genetic analyses of fertility. Currently, there are more than 200 genes known that are involved in the production of fertile sperm cells. The completion of a number of mammalian genome projects will aid in the investigation of these genes in different species. Great progress has been made in the understanding of genetic aberrations that lead to male infertility. Additionally, the first genetic mechanisms are being discovered that contribute to the quantitative variation of fertility traits in fertile male animals. As artificial insemination (AI) represents a widespread technology in horse breeding, semen quality traits may eventually become an additional selection criterion for breeding stallions. Current research activities try to identify genetic markers that correlate to these semen quality traits. Here, we will review the current state of genetic research in male fertility and offer some perspectives for future research in horses.

Animals↗
PubMed2004

Effects of different artificial insemination techniques and sperm doses on fertility of normal mares and mares with abnormal reproductive history.

The effects of different artificial insemination (AI) techniques and sperm doses on pregnancy rates of normal Hanoverian breed mares and mares with a history of barrenness or pregnancy failure using fresh or frozen-thawed sperm were investigated. The material included 187 normal mares (148 foaling and 39 young maiden mares) and 85 problem mares with abnormal reproductive history. Mares were randomly allotted into groups with respect to AI technique (routine AI into the uterine body, transrectally controlled deep intracornual AI ipsilateral to the preovulatory follicle, or hysteroscopic AI onto the uterotubal junction ipsilateral to the preovulatory follicle), storage method of semen (fresh, frozen-thawed), AI volume (0.5, 2, 12 ml), and sperm dose (50 x 10(6) or 300 x 10(6) progressively motile sperm (pms) for fresh semen and 100 or 800 x 10(6) frozen-thawed sperm with >35% post-thaw motility). The mares were inseminated once per cycle, 24 h after hCG administration when fresh semen was used, or 30 h for frozen-thawed semen. Differences in pregnancy rates between treatment groups were analyzed by Chi-squared test, and for most relevant factors (insemination technique, mare, semen, and stallion) expectation values and confidence intervals were calculated using multivariate logistic models. Neither insemination technique, volume, sperm dose, nor mare or stallion had significant effects (P > 0.05) on fertility. Type of semen, breeding mares during foal heat, and an interaction between insemination technique, semen parameters, and mares did have significant effects (P < 0.05). In problem mares, frozen semen AI yielded significantly lower pregnancy rates than fresh semen AI (16/43, 37.2% versus 25/42, 59.5%), but this was not the case in normal mares. In normal mares, hysteroscopic AI with fresh semen gave significantly (P < 0.05) better pregnancy rates than uterine body AI (27/38, 71% versus 18/38, 47.3%), whereas in problem mares this resulted in significantly lower pregnancy rates than uterine body AI (5/15, 33.3% versus 16/19, 84.2%). Our results demonstrate that for problem mares, conventional insemination into the uterine body appears to be superior to hysteroscopic insemination and in normal mares, the highest pregnancy rates can be expected by hysteroscopic insemination.

Animals↗
PubMed2004

Influence of exogenous GnRH on sexual behavior and frozen/thawed semen viability in stallions during the non-breeding season.

Twelve fertile stallions were divided into two groups, either receiving gonadotropin-releasing hormone (GnRH) (n = 6) or Placebo (n = 6). Based on the history of frozen/thawed semen characteristics three stallions within each group were assigned as being "good freezers" [GnRH (+); Placebo (+)] and three stallions were assigned as being "poor freezers" [GnRH (-); Placebo (-)]. The study was performed as a "blinded" investigation and stallions were treated twice daily by an intramuscular injection of 1 ml GnRH (Buserelin), 50 microg) or Placebo. The experiment was divided into three time periods. Period A (pre-treatment) was performed between 16 November and 20 December; Period B (treatment) was performed during 6 weeks between 21 December and 31 January; and Period C (post-treatment) was performed between 1 February and 12 February. Semen was collected every Monday, Wednesday, Friday, and analysed for motion characteristics by the use of a computerized semen analyser, and sperm morphology immediately after collection. The spermatozoa were cryopreserved, stored in liquid nitrogen, and evaluated for motility (computer assisted semen analysis), membrane integrity (carboxyfluoresceine diacetate (CFDA) combined with propidium-iodide (PI), CFDA/PI), viability and sperm morphology (Eosine-Nigrosine, EN), and osmotic reactivity (hypo-osmotic swelling test, HOS) following thawing in a water bath. The viability of spermatozoa was expressed as the difference between pre-freeze and post-thaw values. A libido score of 1-4, the number of mounts on the phantom before ejaculation, and ejaculation latency were used to evaluate the stallions sexual behavior. Effect of treatment was analysed by comparing time intervals within groups as well as comparing groups within time intervals using SAS statistics software. GnRH treatment decreased the number of mounts before ejaculation (GnRH (total): 2.5 +/- 1.14 versus 1.8 +/- 1.06, P < 0.05), and shortened ejaculation latency. Cessation of treatment increased ejaculation latency in the GnRH group (4.7 +/- 4.98 min versus 7.2+/-7.88min, P<0.05). With the exception of libido score all parameters of sexual behavior were superior in the GnRH (+) group compared to the Placebo (-) group during the treatment period (P < 0.05). GnRH administration increased progressive motility (GnRH (+): 30.7 +/- 10.74% versus 38.4 +/- 15.1%, P < 0.05; GnRH (total): 24.9 +/- 11.80% versus 31.9 +/- 14.68%, P < 0.05), membrane intact spermatozoa CFDA/PI (GnRH (-): 16.8 +/- 7.17% versus 26.2 +/- 7.02%, P < 0.05; GnRH (total): 23.1 +/- 12.33% versus 29.5 +/- 10.77%, P < 0.05) and HOS positive spermatozoa (GnRH (+): 33.2 +/- 11.29% versus 42.2 +/- 10.36%, P < 0.05; GnRH (total): 32.9 +/- 10.23% versus 40.1 +/- 10.30%, P < 0.05) of frozen/thawed spermatozoa. Following cessation of treatment, the viability of frozen/thawed spermatozoa decreased. GnRH treated stallions had lower losses of live stained spermatozoa (EN) compared to the Placebo group (GnRH (total): 17.6 +/- 4.77 versus Placebo (total): 27.2 +/- 5.44, P < 0.05). This was particularly observed in the "poor freezer" group (GnRH (-): 16.6 +/- 4.35 versus Placebo (-): 31.3 +/- 5.87; P < 0.05). In conclusion, exogenous GnRH was shown to improve sexual behavior and increase the quality of frozen/thawed spermatozoa in fertile stallions during the non-breeding season. Nevertheless, it seems that, although significance was achieved relative to improvement to post-thaw sperm quality, that the "real" change in sperm quality seems negligible in fertile stallions. The mechanism of GnRH effect was not determined but this study may support the possibility of a direct gonadal or epididymal effect of exogenous GnRH in the stallion.

Animals↗
PubMed2004

Effect of semen collection practices on sperm characteristics before and after storage and on fertility of stallions.

This study analyzed effects of different methods and intervals of semen collection on the quantity and quality of fresh, cool-stored, and frozen-thawed sperm and fertility of AI stallions. In Experiment 1, ejaculates were obtained from six stallions (72 ejaculates per stallion) using fractionated versus non-fractionated semen collection techniques. Initial sperm quality of the first three jets of the ejaculate was not different from that of total ejaculates. Centrifugation of sperm-rich fractions before freezing improved post-thaw motility and sperm membrane integrity when compared to non-centrifuged sperm-rich fractions or non-fractionated centrifuged ejaculates (P<0.05). In Experiment 2, semen from four stallions (60-70 ejaculates per stallion) was collected either once daily or two times 1h apart every 48 h. The first ejaculates of double collections had significantly higher sperm concentrations, percentages of progressively motile sperm (PMS) after storage for 24h at 5 degrees C and lower percentages of midpiece alterations than single daily ejaculates. Semen collected once daily showed significantly lower values of live sperm after freezing and thawing than the first ejaculate of two ejaculates collected 1h apart every 48 h. In Experiment 3, semen was collected from 36 stallions (> or =12 ejaculates per stallion) during the non-breeding season and the time to ejaculation and the number of mounts was recorded. When time to ejaculation and the number of mounts increased, volume and total sperm count (TSC) also increased (P<0.05), whereas a decrease was observed in sperm concentration, percentage of PMS after storage for 24 h at 5 degrees C, percentage of membrane-intact sperm in fresh semen (P<0.05) as well as motility and percentage of membrane-intact sperm of frozen-thawed sperm (P<0.05). In Experiment 4, AI data of 71 stallions were retrospectively analyzed for the effect of number of mounts per ejaculation and frequency, time interval of semen collections on pregnancy, and foaling rates (FRs) of mares. Semen volume increased, but sperm concentration and percentage of PMS after 24-h cool-storage decreased with increasing number of mounts on the phantom (P<0.05). A statistically significant inter-relationship was demonstrated between frequency and interval of semen collection and FR. Mares inseminated with stallions from which semen was collected frequently (> or =1 on an average per day) showed significantly higher FRs than mares inseminated with semen from stallions with a daily collection frequency of 0.5-1 or <0.5. FR of mares inseminated with stallions having 0.5-1 days between semen collections was significantly better than FR of mares that were inseminated with stallions having semen collection intervals of 1-1.5 days or >2.5 days.

Animals↗
PubMed2003

The effects of different insemination regimes on fertility in mares.

This study investigated the effects of different artificial insemination (AI) regimes on the pregnancy rate in mares inseminated with either cooled or frozen-thawed semen. In essence, the influence of three different factors on fertility was examined; namely the number of inseminations per oestrus, the time interval between inseminations within an oestrus, and the proximity of insemination to ovulation. In the first experiment, 401 warmblood mares were inseminated one to three times in an oestrus with either cooled (500 x 10(6) progressively motile spermatozoa, stored at +5 degrees C for 2-4 h) or frozen-thawed (800 x 10(6) spermatozoa, of which > or =35% were progressively motile post-thaw) semen from fertile Hanoverian stallions, beginning -24, -12, 0, 12, 24 or 36 h after human chorionic gonadotrophin (hCG) administration. Mares were injected intravenously with 1500 IU hCG when they were in oestrus and had a pre-ovulatory follicle > or =40mm in diameter. Experiment 2 was a retrospective analysis of the breeding records of 2,637 mares inseminated in a total of 5,305 oestrous cycles during the 1999 breeding season. In Experiment 1, follicle development was monitored by transrectal ultrasonographic examination of the ovaries every 12 h until ovulation, and pregnancy detection was performed sonographically 16-18 days after ovulation. In Experiment 2, insemination data were analysed with respect to the number of live foals registered the following year. In Experiment 1, ovulation occurred within 48 h of hCG administration in 97.5% (391/401) of mares and the interval between hCG treatment and ovulation was significantly shorter in the second half of the breeding season (May-July) than in the first (March-April, P< or =0.05). Mares inseminated with cooled stallion semen once during an oestrus had pregnancy rates comparable to those attained in mares inseminated on two (48/85, 56.5%) or three (20/28, 71.4%) occasions at 24 h intervals, as long as insemination was performed between 24 h before and 12 h after ovulation (78/140, 55.7%). Similarly, a single frozen-thawed semen insemination between 12 h before (31/75, 41.3%) and 12 h after (24/48, 50%) ovulation produced similar pregnancy rates to those attained when mares were inseminated either two (31/62, 50%) or three (3/9, 33.3%) times at 24 h intervals. In the retrospective study (Experiment 2), mares inseminated with cooled semen only once per cycle had significantly lower per cycle foaling rates (507/1622, 31.2%) than mares inseminated two (791/1905, 41.5%), three (464/1064, 43.6%) or > or =4 times (314/714, 43.9%) in an oestrus (P< or =0.001). In addition, there was a tendency for per cycle foaling rates to increase when mares were inseminated daily (619/1374, 45.5%) rather than every other day (836/2004, 42.1%, P = 0.054) until ovulation. It is concluded that under conditions of frequent veterinary examination, a single insemination per cycle produces pregnancy rates as good as multiple insemination, as long as it is performed between 24 h before and 12 h after AI for cooled semen, or 12 h before and 12 h after AI for frozen-thawed semen. If frequent scanning is not possible, fertility appears to be optimised by repeating AI on a daily basis.

Animals↗
PubMed2003

Application of techniques for sperm selection in fresh and frozen-thawed stallion semen.

The objective of this research was to improve the techniques in processing chilled and frozen-thawed horse semen. In a preliminary experiment (Exp. I), different techniques for sperm selection and preparation [Swim-up, Glass wool (GW) filtration, Glass wool Sephadex (GWS) filtration; Percoll] were tested for their suitability for equine spermatozoa and results were compared with the routine procedure by dilution (Exp. I). In the main experiment (Exp. II), two sperm preparation techniques (GWS, Leucosorb) refering to the results of Exp. I and a previous study of our group (Pferdcheilkunde 1996 12, 773) were selected for processing complete ejaculates either for cooled-storage or cryopreservation. In a third experiment (Exp. III), pregnancy rates from inseminations with semen processed according to the techniques tested in Exp. II were compared with those obtained with semen processed according to routine procedures. In Exp. I (six stallions, six ejaculates/stallion), between 48 and 92% of spermatozoa were lost following the different sperm selection procedures (p < 0.05). Preparation of sperm increased percentage of progressively motile spermatozoa (pms) [Swim-up, GW, GWS vs dilution, Percoll (p < 0.05)] and decreased percentage of sperm head abnormalities [Swim-up, GW, GWS vs dilution, Percoll (p < 0.05)] probably by not improving the quality of individual cells, but by elimination of spermatozoa of inferior quality. In Exp. II (eight stallions, three ejaculates/stallion) Leucosorb and GWS procedures allowed the filtration of large volumes (extended ejaculates) for routine laboratory practice. GWS and Leucosorb filtration resulted in increased motility, membrane integrity and sperm viability after storage of spermatozoa until 48 h at +5 degrees C when compared with control (diluted) and centrifuged semen (p < 0.05). Significantly more spermatozoa were recovered after centrifugation (87.8 +/- 15.4%) compared with GWS (63.5 +/- 18.6%) and Leucosorb filtration (53.6 +/- 22.3%). GWS or Leucosorb procedure resulted in successful cryopreservation of stallion semen without centrifugation for removal of seminal plasma. The per cycle conception rate of inseminated mares using 200 x 106 pms transferred within 8 h after collection of semen was not affected by GWS filtration or Leucosorb separation when compared with centrifugation (n.s.; Exp. III). In conclusion, GWS and Leucosorb filtration results in the improvement of semen quality and should be considered as a method for stallion semen processing. Additional studies are needed for the evaluation of potentially higher fertilizing ability of stallion spermatozoa separated by techniques for sperm selection.

Animals↗
PubMed2000

Assessing equine sperm-membrane integrity.

The swelling of cells in a hypo-osmotic medium has been described as an important criterion for assessing the functional integrity of the sperm plasma membrane. The resistance of equine spermatozoa to osmolarity changes was studied by extending 98 semen samples collected from nine stallions in media at five osmolarities (300, 200, 150, 100, and 50 mOsmol l(-1)). The response of the cells was measured by the spermatocrit technique and eosin staining. Spermatocrit determines the increase on spermatozoal volume under hypo-osmotic conditions, a sign of functional integrity of sperm plasma membrane, whereas the eosin staining evaluates the viability of spermatozoa. A significant positive correlation (P<0.01) was observed between spermatocrit values and percentage of eosin-unstained cells. Spermatocrit measurements and eosin staining proved to be useful methods to evaluate the integrity of sperm plasma membrane under hypo-osmotic conditions and could be used as an additional criterion to predict semen preservation ability.

Animals↗
PubMed2000

Cyclical endometrial steroid hormone receptor expression and proliferation intensity in the mare.

The aims of this study were to investigate the steroid hormone receptor expression and the proliferation intensity during the equine endometrial cycle by immunohistological methods, established for routine examination of formalin-fixed, paraplast-embedded specimens. Endometrial biopsy specimens were obtained during one cycle from 7 mares. In comparison with the blood steroid hormone levels the quantity and distribution of oestrogen (ER) and progesterone receptors (PR) and the proliferation marker Ki-67 antigen expression were investigated. Rising 17beta-oestradiol concentrations in preoestrus induce a synchronous expression of ER, PR and Ki-67 antigen in stromal cells. In the early dioestrus 17beta-oestradiol levels decrease and progesterone levels reach their maxima. This correlates with an intense proliferation activity and the highest hormone receptor expression in epithelial cells. In accordance to the morphological features of asynchronous glandular differentiation in fibrotic areas (endometrosis) their epithelial hormone receptor expression is out of phase.

Animals↗
PubMed1999

[Veterinary recommendations for the handling of equine virus arteritis (EVA) in practical breeding care].

The equine virus arteritis (EVA) consistently epidemically varying throughout the different breeds of the horse breeding countries is up to now only of lower significance by means of the typical clinical manifestation as well as an abortion causing factor. The susceptibility of the sexual mature stallions against the equine arteritis virus (EAV) causes different infection response which may lead to some restrictions in their use in natural breeding especially in the artificial insemination. In a certain not precisely predictable part of the stallion population EAV infection will cause a transient or permanent virus presence in the accessorial apparatus of the genital tract with transient or permanent shedding of the virus via seminal secretions. This makes the stallion to one of the dominant factors of the propagation of the field virus. The use of EAV shedding stallions in natural breeding or AI is very risky and only justifiable under certain precautions and additional measurements e.g. in EAV-seropositive or vaccinated mares. A consistent progress in the defeat of the disease can be expected from vaccination of the seronegative stallions with dead or inactivated live vaccines as they are considered to be able to prevent the establishing of EAV shedder status.

Abortion, Veterinary↗
PubMed1998

[Fundamentals of hygiene to be used for stallions in an instrumental artificial insemination].

Equine artificial insemination (AI) meanwhile has been widely established in the warm blood horse industry. Because of its importance consistent hygienic aspects and their significance for the use of stallions as semen donors in AI-programs are presented and clarified. Incidence as well as importance of equine venereal infectious diseases are considered. Data of physiological bacterial genital flora and treatment principles of therapeutic control of venereal infectious bacterial agents as well as a model of control of Equine Viral Arteritis are given. A prophylactic hygiene program for donor stallions in routine AI including special microbiological monitoring is presented.

Animals↗
PubMed1997

[Separation techniques ro achieve vital and reproduction competent equine spermatozoa populations--a survey].

Equine ejaculates are significantly characterized by widely varying parameters especially in those of practical relevance for equine Al. Therefore it is of interest for practical purposes to get subpopulations of concentrated, vital, and competent spermatozoa from the origin ejaculates. Special preparation of the donor stallions will stabilize sperm output. Fractionated semen collection from stallions supplies sperm enriched seminal fractions very useful to work with further in semen preservation. Most important to achieve a concentrated sperm subpopulation are semen manipulations post ejaculation represented conventionally in semen centrifugation. In the last decade alternative measurements have been introduced. Above all semen filtration using glasswool-sephadex and more recently membrane techniques gave good results indicating that these new techniques may replace semen centrifugation in the future. This article gives a survey of the different starting points and methods for separation of vital and concentrated sperm subpopulations of equine semen.

Animals↗