Ultrasonographic evaluation of the conceptus from days 10 to 60 of pregnancy in jennies

Assessment of Fetal Aortic, Thoracic, and Heartbeat in Healthy Donkey Pregnancies

Practitioners are frequently requested to diagnose and stage pregnancy in donkeys with unknown breeding dates; however, scant work has been done to stage pregnancy in the species. Therefore, this study aimed to determine the association between measurements of fetal aortic, thoracic, and heartbeat with gestational age in donkeys carrying and delivering healthy foals. Multiparous Dezhou donkeys (n = 50) ranging from 4 to 16 years were enrolled in the study by 150 days of gestation. Transabdominal ultrasonography coupled with a 3.5 MHz sectorial convex transducer was performed at 30 day-intervals until delivery to obtain fetal aortic, thoracic, and fetal heartbeat measurements. Data were tested for normality with Shapiro- Wilk's test and then ANOVA and Tukey's. Statistical significance was set at P < .05. The mean duration of pregnancy was 356.6 ± 10.6 days (339-368). There were significant associations between gestational age and fetal aortic (r = 0.89) and thoracic (r = 0.88) measurements. Fetal heartbeat (r = -0.76) was negatively correlated with gestation length. The fetal aortic and thoracic measurements increased from the seventh month of gestation to the term (P < .001). The fetal heartbeat remained steady from 150 days to 270 days of gestation, then continuously decreased from 270 days until parturition (P < .001). In conclusion, fetal aortic and thoracic measurements are strongly associated with gestational age in donkeys. Fetal heartbeat decreases with advanced pregnancy.

Early Pregnancy in Jennies in the Caribbean: Corpus Luteum Development and Progesterone Production, Uterine and Embryo Dynamics, Conceptus Growth and Maturation

Simple Summary

An understanding of the basic mechanisms of reproduction in donkeys is essential, for several reasons. Some donkey breeds are threatened or endangered, and efforts to save these species depend on improved knowledge of reproductive processes. In some parts of the world, donkeys continue to be valued for purposes of work, recreation, or even meat or milk production, as well as the breeding of mules, and reproduction is essential to maintain suitable populations. In others, donkey populations have become feral and represent a nuisance or even a danger to human populations, and improved contraceptive methods are required. Whether for enhancing or inhibiting reproduction, species-specific information is valuable. While the mare has been extensively studied, few studies have explored early pregnancy in jennies. Therefore, this study characterized early embryo development and differences in progesterone profile and changes in the corpus luteum between pregnant and non-pregnant jennies.

Abstract

We aimed to characterize early embryo development and changes in corpus luteum (CL) development and progesterone profile in pregnant vs. non-pregnant jennies. Eight jennies were enrolled in the study. In the first two cycles, the jennies were monitored by transrectal ultrasonography and had blood harvested for hormone profile assay. In the third cycle, jennies were bred by a jack of proven fertility. Jennies were then monitored and sampled for up to 30 days of pregnancy. Data were evaluated by random-effects multiple linear regression, and correlations were expressed as Pearson’s correlation coefficient. Progesterone concentration rose rapidly from ovulation (D0) until D7, plateaued until D12–14, then precipitously declined between D14 and 15, remaining low until the next ovulation in non-pregnant cycles. In the pregnant jennies, the progesterone concentration rose to maximal concentrations on D7–11, being higher at this stage than in non-pregnant cycles, then declined gradually up to D30. In all cycles, the volume of the CL increased steadily until D6, when it plateaued in pregnant jennies. For non-pregnant jennies, CL volume decreased slowly from D6 to D11 and then had a faster drop. Uterine tone increased following ovulation, becoming turgid around the day of embryo fixation (D15.0 ± 0.9). An embryonic vesicle (EV) was first detected on D9.3 ± 0.5 (2.4 ± 0.5 mm). The EV remained spherical until D18.6 ± 1.4. The embryo proper was first detected ventrally in the vesicle on D20.8 ± 1.1 and the embryonic heartbeat by D22.0 ± 0.9. The allantoic sac was identified at D24.0 ± 0.9, and at D30, the allantoic sac filled the ventral half of the EV. This study provides evidence that higher cumulative concentrations of progesterone are correlated to size of the EV, and there were changes in the luteal dynamics and progesterone profiles in pregnant vs. non-pregnant jennies.

Equine embryo mobility. A game changer

The equine embryo or embryonic vesicle on Days 11-15 postovulation travels with profound physiologic purpose throughout the lumen of the two uterine horns and uterine body making 12 to 22 trips between the two uterine horns per day. This phenomenon is termed embryo mobility and is unique in equids among domestic species. Apparently, the embryo first reaches the uterine body on Days 8 or 9. Mobility increases to maximum by Days 11 or 12 and continues until an abrupt cessation of mobility (fixation) on Days 15 (ponies) or 16 (horses and donkeys). The embryo is propelled by uterine contractions in response to the production of apparently both PGF2α and PGE2 by both the embryo and uterus. An increase in endometrial vascular perfusion accompanies the mobile embryo as it moves from horn to horn. Restricting the embryo to one uterine horn by a ligature has indicated that specific roles of the traveling embryo include the stimulation of uterine contractions, tone, vascularity, and edema and to curtail the production of the luteolysin (PGF2α) by the uterus. The increase in uterine tone, decrease in diameter of the uterine horns, and a flexure in the caudal portion of each horn collaborate in the selection of a horn of fixation. Embryo mobility is a game changer that has solved several long-time enigmas in mare reproduction and has provided a needed and effective finger/thumb compression method for eliminating one member of a twin set.

Label-Free Mass Spectrometry-Based Quantitative Proteomics Analysis of Serum Proteins During Early Pregnancy in Jennies (Equus asinus)

Early pregnancy in jennies is routinely determined by palpation per rectum or ultrasonography and also by detecting steroid hormone and chorionic gonadotropin levels in the blood, plasma, and serum. Herein we applied label-free mass spectrometry-based quantitative proteomics to identify serum proteins that were differentially expressed between early pregnant (day 45 after ovulation) and non-pregnant jennies. Bioinformatics analysis allowed illustration of pathways potentially involved in early pregnancy. We identified 295 proteins from a total of 2,569 peptides. Twenty-five proteins (22 upregulated and three downregulated) were significantly differentially expressed between the early pregnant and non-pregnant groups. The majority of the differentially expressed proteins were involved in defense response, early embryonic development, and hormone signaling pathways. Furthermore, functional protein analyses suggested that proteins were involved in binding, enzyme inhibitor activity, and enzyme regulator activity. Five serum proteins—granulin precursor/acrogranin, transgelin-2, fibronectin, fibrinogen-like 1, and thrombospondin 1—can be considered as novel, reliable candidates to detect pregnancy in jennies. To the best of our knowledge, this is the first study to use label-free mass spectrometry-based quantitative proteomics to analyze serum proteins during early pregnancy in jennies. Our results should facilitate the identification of valuable pregnancy diagnostic markers in early pregnant jennies.

Key Aspects of Donkey and Mule Reproduction

Donkeys are nonseasonal, polyestrous, territorial, and nonharem breeders. Although there are many similarities between horses and donkeys, there are also reproductive features that differ, from the longer cervix in the jenny to spermatogenic efficiency in the jack. Mules display reproductive cyclic activity but are rarely fertile. Frozen donkey semen has high pregnancy rates in mares, but lower rates in jennies. This article reviews key aspects of donkey and mule reproductive physiology, reproductive medicine, and assisted reproductive techniques that are useful for practitioners offering assisted reproductive techniques, and also for practitioners with the occasional client with a basic reproductive question.

The mule (Equus mulus) as a recipient of horse (Equus caballus) embryos: Comparative aspects of early pregnancy with mares

The aim of this study was to compare the embryonic and early fetal development of horse embryos between recipient mules and mares from day 10-60 of pregnancy, in addition to hormonal (eCG and progesterone), ovarian, and uterine characteristics for approximately 4 months. Embryo donor mares (n = 5) and two groups of recipients (acyclic mules, n = 7; cyclic mares, n = 7) were used. Donor mares were monitored daily by transrectal ultrasonography and inseminated using fresh semen. Cyclic recipient mares were synchronized with the donor's ovulation using PGF2α and deslorelin acetate. Mules were prepared for the embryo transfers with estrogen and progestagen. Embryo collection and transfer were performed 8 days after ovulation of the donor mares. Pregnancy diagnosis with ultrasonography began 1 day after embryo transfer. After pregnancy confirmation, the recipient mules received long-acting progesterone once weekly for at least 120 days. The first day of detection (day 10) of an embryonic vesicle (EV) was similar between mules and mares. A period of extensive intrauterine mobility of the embryonic vesicle was observed similarly in mules and mares from days 10-17. The day of fixation of the EV in mules tended to be 1-day earlier than in mares; however, the diameter and growth rate of the EV did not differ between the two species. The embryo proper was first detected at day 20, and the crown-rump, width, and diameter were similar between the two recipient types. The heartbeat and allantoic sac tended to be detected 1 day later in mules than in mares, while the umbilical cord was first observed around day 40 in both species. Besides the expected differences found in ovarian aspects and eCG production, similar endometrial diameter, uterine tone and echotexture, and progesterone levels were seen between the two types of recipients. In conclusion, striking ultrasound similarities in equine embryo and fetal development, and uterine characteristics were seen between mules and mares used as recipients of horse embryos.

Field ultrasound evaluation of some gestational parameters in jennies

The aim of this study was to collect and analyze ultrasound measurements of fetal-maternal structures during normal and pathological pregnancies in jennies, a livestock species of growing interest. For two breeding seasons, 38 jennies of different breeds and crossbreeds aged between 3 and 18 years were monitored weekly by transrectal examination using a portable Esaote ultrasound (MyLab™ 30 GOLD VET) with a 5-7.5 MHz probe. The jennies were divided into two groups, < 250 kg and >250 kg body weight, and the dates of conception and parturition/abortion were recorded to calculate pregnancy length. Descriptive statistics were performed for the following variables: pregnancy length and maternal-fetal parameters (measurements of the orbit, gastric bubble, thorax, abdomen, gonads, heart rate, umbilical artery velocimetry, and combined utero-placental thickness). A total of 68 pregnancies were studied, 36 of which ended during the study period. The average pregnancy length was 370.82 ± 16.6 days for full-term pregnancies (N = 28, 77.8%) and 316.13 ± 36.6 days for abortions (N = 8, 22.2%). The season of conception and fetal gender did not affect the pregnancy length. Pregnancy examination can reasonably be performed by two weeks after last service if ovulation date is not known. The orbital diameter was the most reliable parameter for monitoring the physiological development of the embryo and fetus, and it was strongly related to the gestational age. No differences in fetal development were observed in relation to the mother's body weight. The combined utero-placental thickness was not associated with the gestational age and thickening and edema, frequently observed, were not associated with fetal pathologies.

Ultrasonographic fetometry and determination of fetal sex in buffaloes (Bubalus bubalis)

The aim of the current study was to establish ultrasonic biometric threshold of different fetal parts in buffaloes and to evaluate the feasibility and accuracy of ultrasonic fetal sex determination. Serial ultrasonographic examinations were carried out on twelve pregnant buffalo-cows, during which fetal parts were measured, and fetal sex and presentation were determined. The obtained results revealed that embryo and amniotic vesicle (AV) were detected by the forth and fifth week of pregnancy, respectively. Organization was observed by the seventh week, while ossification was indicated between the eighth and 10th week. High correlations were found between different studied parameters and gestational age, where the highest correlation was found with the crown-rump length (CRL) and amniotic vesicle diameter (AVD) at the early-gestation; the biparietal diameter (BPD) at the mid-gestation; and the eyeball diameter (EBD) at the mid- and late-gestation. The results also revealed that the best window for fetal sexing was found between the 10th and 18th week of gestations, with an overall accuracy of 97.1%. The final polarity with all fetuses in anterior presentation was adopted by the 30th week. In conclusion, the overall data indicated the feasibility and value of ultrasonographic fetometry in buffaloes for evaluation of fetal development, estimation of gestational age and determination of fetal sex.

Doppler evaluation of maternal and foetal vessels during normal gestation in queen

The aim of this work is to evaluate the haemodynamic characteristics of maternal and foetal vessels during normal pregnancy in queens, using colour Doppler and pulsed wave Doppler ultrasonography, in order to obtain information about maternal and foetal circulation. The blood waveforms of the uteroplacental arteries, aorta, caudal cava vein and umbilical cord of the fetuses were recorded weekly in seven healthy pregnant queens. Also, the measurements of peak systolic, end diastolic velocities, resistance and pulsatility indices were carried out. Uteroplacental blood flow was biphasic while the ones of the umbilical artery and aorta were first systolic and then diastolic. The caudal cava vein showed a typical waveform of venous vessels. During gestation the EDV and PSV of foetal vessels increased (alpha<0.05) while the PI and RI of all vessels examined decreased (alpha<0.05) except for the IP of the aorta. The Doppler ultrasonography, also in queens, can be used to evaluate the characteristics of maternal and foetal vessel flow and their progressive changes during pregnancy. This study can be considered the basis for further contribution in diagnosing and monitoring high-risk pregnancies in Veterinary Medicine.