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1.
Fernando LóPEZ-GATIUS Irene LóPEZ-HELGUERA Fabio DE RENSIS Irina GARCIA-ISPIERTO 《The Journal of reproduction and development》2015,61(5):465-471
This study compared the responses shown by lactating dairy cows to four different P4-based protocols for AI at estrus. Cows with no estrous signs 96 h after progesterone intravaginal device (PRID) removal were subjected to fixed-time AI (FTAI), and their data were also included in the study. In Experiment I, follicular/luteal and endometrial dynamics were assessed every 12 h from the beginning of treatment until AI. The estrous response was examined in Experiment II, and fertility was assessed in both experiments. The protocols consisted of a PRID fitted for five days, along with the administration of different combinations of gonadotropin releasing hormone (GnRH), equine chorionic gonadotropin and a single or double dose (24 h apart) of prostaglandin F2α. In Experiment I (40 cows), animals receiving GnRH at the start of treatment showed a significantly higher ovulation rate during the PRID insertion period while estrus was delayed. In Experiment II (351 cows),
according to the odds ratios, cows showing luteal activity at the time of treatment were less likely to show estrus than cows with no signs of luteal activity. Treatment affected the estrous response and the interval from PRID removal to estrus but did not affect conception rates 28–34 days post AI. Primiparous cows displayed a better estrous response than multiparous cows. Our findings reveal acceptable results of 5-day P4-based protocols for AI at estrus in high-producing dairy cows. Time from treatment to estrus emerged as a good guide for FTAI after a 5-day P4-based synchronization protocol. 相似文献
2.
Sydney HughesKatheryn Cerny BS MS Juliana CamposMats Troedsson DVM PhD ACT Barry BallEdward Squires MS PhD ACT 《Journal of Equine Veterinary Science》2014
Equine chorionic gonadotropin (eCG), obtained from pregnant mares, is used for assisted reproductive technologies in laboratory rodents and livestock. The objective of the present study was to use equine follicle-stimulating hormone (eFSH) to increase the incidence of twin pregnancies, through multiple ovulations, and increase eCG. Nineteen light horse–type mares were enrolled in the study. The control group (n = 9) was bred with fresh or cooled semen and given human chorionic gonadotropin (hCG) at the time of breeding. The second group (n = 10) was given 12.5 mg of eFSH intramuscularly twice a day beginning 5–7 days after ovulation. Prostaglandin F2α was administered intramuscularly the second day of eFSH treatment. Treatment with eFSH continued until follicles were >35 mm in diameter, and mares were then given no treatment for 36 hours. The mares were then bred with fresh or cooled semen from the same stallion as the control group and given hCG. Blood samples were taken weekly from day 35 to day 105 after ovulation. Serum concentration of eCG was obtained, and data were analyzed with multivariate analysis using the mixed procedure. Significance was set at P < .05. Data were combined for all mares carrying twins and compared with those carrying singletons. The group of mares carrying twins had higher peak concentrations of eCG and higher values for area under the curve compared with mares carrying singletons (P < .05). These results suggest inducing twins could be a method used to increase eCG production. 相似文献
3.
We report upon an ageing Thoroughbred mare which showed remarkably similar and abnormally prolonged profiles of equine Chorionic Gonadotrophin (eCG) in her bloodstream during successive pregnancies sired by the same stallion. The first pregnancy was aborted at Day 75 after ovulation in conjunction with a precipitous decline in eCG concentrations which occurred immediately after the peak level had been reached. The second pregnancy, which proceeded safely to term, also involved a similar sharp fall in eCG concentrations after attainment of the peak values. Possible causes of the extended lifespan of the eCG‐secreting endometrial cups in this animal are discussed. 相似文献
4.
马绒毛膜促性腺激素(Equine chorionic gonadotropin,eCG)是马属动物妊娠早期由子宫内膜杯分泌的一种异源二聚体糖蛋白,文章综述了妊娠母马子宫内膜杯的结构、eCG的生物学特性、eCG在动物繁殖中的应用、不同马属动物、马的品种、年龄、及母马所怀胎儿性别等遗传、生理因素对妊娠母马eCG分泌水平的影响。研究表明,怀驴骡母驴、轻年怀头胎的妊娠母马、怀雌性胎儿的妊娠母马eCG的分泌水平较高。eCG作为一种胎源的糖蛋白很可能在母体的免疫耐受中发挥特定的作用。 相似文献
5.
The stimulatory role of equine Chorionic Gonadotropin (eCG) in the production of steroid hormones was evaluated during the first 4 months of pregnancy in mares impregnated by either stallions or jack donkeys. Twenty mares were divided in two groups: Mares in the first group were inseminated with stallion semen (horse pregnancies), and those in the second group were inseminated with donkey semen (mule pregnancies). Blood samples were collected twice weekly from day 30 to day 120 of pregnancy to determine the concentrations of eCG, progesterone, androstenedione, and testosterone. Analysis of variance for repeated measures was used to compare the concentrations of each hormone between groups. Linear regression models that considered the linear and quadratic effects of week of gestation as well as the linear and quadratic effects of the concentrations of eCG on the production of each steroid hormone were carried out. Concentrations of eCG, progesterone, and androstenedione were higher in horse than in mule pregnancies (P < .01 for eCG and P < .05 for progesterone and androstenedione). Testosterone concentrations were also higher in horse pregnancies than in mule pregnancies at weeks 7, 9, and 10 (P < .05). Regression analysis indicated that eCG had considerable stimulatory effects on the secretion of progesterone and androstenedione and weaker effects on the secretion of testosterone. The results suggest that eCG stimulates luteal production of progesterone, androstenedione, and testosterone in horse and mule pregnancies, these effects being more evident in horse pregnancies than in mule pregnancies due to the higher concentrations of eCG in horse pregnancies. 相似文献
6.
Irina GARCIA-ISPIERTO Fernando LóPEZ-GATIUS 《The Journal of reproduction and development》2014,60(6):426-432
This study compares in two experiments the responses of lactating dairy cows to four different progesterone-based protocols for fixed-time artificial insemination (FTAI) in terms of their effects on follicular/luteal dynamics and fertility. The protocols consisted of a progesterone intravaginal device fitted for five days, along with the administration of different combinations of gonadotropin releasing hormone, equine chorionic gonadotropin and a single or double dose (24 h apart) of prostaglandin F2α. In Experiment I, the data were derived from 232 lactating cows. Binary logistic regression identified no effects of treatment on ovulation failure or multiple ovulation 10 days post artificial insemination (AI). Based on the odds ratio, the likelihood of ovulation failure was lower (by a factor of 0.1) in cows showing at least one corpus luteum (CL) upon treatment than in cows lacking a CL; repeat breeders (> 3 AI) and cows with multiple CLs at treatment
showed lower (by a factor of 0.44) and higher (by a factor of 9.0) risks of multiple ovulation, respectively, than the remaining animals. In Experiment II, the data were derived from 5173 AIs. The independent variable treatment failed to affect the conception rate 28–34 days post AI, twin pregnancy or early fetal loss 58–64 days post AI. The results of this study demonstrate the efficacy of 5-day progesterone-based protocols for FTAI. All four protocols examined were able to induce ovulation in both cyclic and non-cyclic animals so that FTAI returned a similar pregnancy rate to spontaneous estrus. Our results suggest that the ovarian response and fertility resulting from each treatment are due more to the effect of ovarian structures at treatment than to the different combinations of hormones investigated. 相似文献
7.
Reasons for performing study: An opportunity to monitor equine chorionic gonadotrophin (eCG) production during 61 pregnancies in 25 Thoroughbred mares mated to the same Thoroughbred stallion was utilised in order to further knowledge regarding factors involved in the production of this hormone. Objectives: To examine the effects of maternal body condition, exercise and parity on eCG production. Methods: In the first experiment, maiden mares were fed either a moderate (n = 9) or an excessive (n = 10) food intake throughout gestation. In the second experiment, 5 mares were exercised daily during pregnancy and eCG production rates were compared to 5 nonexercised mares. In the third experiment, eCG profiles were compared in 9 mares during 3 successive pregnancies. Equine chorionic gonadotrophin secretion was assessed as area under the curve (AUC), peak serum concentration, timing of the peak and the rate of decline. In addition, a mean eCG profile of 61 pregnancies was created to provide means and ranges for the above parameters. Results: In Experiment 1, eCG production was significantly higher in moderately rather than excessively fed mares in terms of AUC and peak eCG concentrations. In Experiment 2, the mean AUC did not differ between exercised and nonexercised animals but mean eCG concentrations were significantly higher in nonexercised mares between Days 60 and 90 of gestation. In Experiment 3, eCG became undetectable significantly earlier in gestation in the third parity. The mean eCG profile of 61 pregnancies showed a peak of 64.5 ± 3.7 iu/ml at 62.4 ± 1.0 days after ovulation and was undetectable by 134.1 ± 1.7 days. Peak eCG levels reduced by 50% 22.6 ± 1.13 days. Conclusions: Some of the factors examined clearly influenced eCG production rate, the secretion of this hormone and its rate of disappearance from the blood. Potential relevance: The results provide insights into some factors that govern the production of the placental gonadotrophin, eCG. 相似文献
8.
本实验通过ELISA检测不同生理状态下的蒙古马和纯血马妊娠母马在妊娠30～100d体内eCG的表达水平,比较品种、母马年龄、胎儿性别对母马eCG分泌水平的影响。结果表明:蒙古马eCG效价在妊娠第60天出现峰值,平均值为82.1IU/mL,100d出现最低值16.6IU/mL,年龄对蒙古马eCG表达水平有影响,3～5岁组极显著高于大于10岁组(P0.01)。纯血马在妊娠60deCG效价到达峰值,平均值为64.8IU/mL,在妊娠第30天出现最低值10.8IU/mL。怀雌性胎儿纯血马eCG分泌水平极显著高于怀雄性胎儿的纯血马(P0.01)。蒙古马eCG的表达水平极显著高于纯血马(P0.01)。 相似文献
9.
Serial ultrasound examinations of the gravid uterus of a Jenny donkey (Equus asinus) carrying a transferred extraspecies horse (Equus caballus) conceptus between 11 and 33 days of gestation demonstrated that the embryo died before Day 33 even though the conceptus persisted in the uterus and the horse chorionic girdle invaded the maternal endometrium to form a circle of typically large horse endometrial cups in the right uterine horn. The high concentrations of horse CG secreted by these cups with its higher than usual ratio of FSH-like to LH-like biological activities of 1.4 compared to the 0.1 ratio of normal donkey CG hyper-stimulated the donkey’s ovaries to develop multiple large accessory follicles and resulting secondary corpora lutea which secreted high concentrations of progestagens that persisted in her bloodstream for the next 90 days. This case illustrated that, in all likelihood, girdle invasion can happen after the death of the embryo indicating autonomy of the chorionic girdle. 相似文献
10.
Early embryo transfer in equids was undertaken simultaneously in the early 1970s in Cambridge, England, and Kyoto, Japan. Both groups achieved limited success when flushing the uterine horn ipsilateral to the side of ovulation but the rates improved markedly when the whole uterus was flushed on realization of the continued movement of the embryo throughout the uterine lumen after day 6. Initial transfers of embryos to recipient mares were carried out surgically, but nonsurgical transfer via the cervix has been used subsequently with increasing success, culminating in pregnancy rates of 75%–90% today. Experimental use of embryo transfer in horses and donkeys demonstrated the unique ability of equids to carry to term a full range of interspecies hybrid conceptuses and extraspecies pregnancies created by embryo transfer. Furthermore, splitting of day 4–8 cell embryos and day 6 compact morulae allowed the creation of genetically identical twin foals. But despite these and other significant advances over the past 45 years, a persisting limitation is the relatively low embryo recovery rates from donor mares treated with exogenous gonadotropins in attempts to induce them to superovulate. This is due to the toughness of the ovarian tunica albuginea which forces ovulation through the ventrally situated ovulation fossa where multiple follicles compete with each other and luteinize before they can ovulate properly. 相似文献