Field ultrasound evaluation of some gestational parameters in jennies

Genetic Characterization of a Novel Equus caballus Papillomavirus Isolated from a Thoroughbred Mare

Papillomaviruses (PVs) are small, non-enveloped viruses, ubiquitous across the animal kingdom. PVs induce diverse forms of infection, such as cutaneous papillomas, genital papillomatosis, and carcinomas. During a survey on the fertility status of a mare, a novel Equus caballus PV (EcPV) has been identified using Next Generation Sequencing, and it was further confirmed with genome-walking PCR and Sanger sequencing. The complete circular genome 7607 bp long shares 67% average percentage of identity with EcPV9, EcPV2, EcPV1, and EcPV6, justifying a new classification as Equus caballus PV 10 (EcPV10). All EcPV genes are conserved in EcPV10, and phylogenetic analysis indicates that EcPV10 is closely related to EcPV9 and EcPV2, genus Dyoiota 1. A preliminary EcPV10 genoprevalence study, carried out on 216 horses using Real Time PCRs, suggested a low incidence of this isolate (3.7%) compared to EcPVs of the same genus such as EcPV2 and EcPV9 in the same horse population. We hypothesize a transmission mechanism different from the one observed in the closely related EcPV9 and EcPV2 that particularly infect Thoroughbreds. This horse breed is usually submitted to natural mating, thus indicating a possible sexual diffusion. No differences were detected for breeds in terms of susceptibility to EcPV10. Further studies are needed to investigate the molecular mechanisms behind the host and EcPV10 infection to explain the reduced viral spread.

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.

Electrolytes and pH of Mammary Gland Secretions Assessments to Detect Impending Parturition and Associations With Placental and Neonate Features in Donkeys

The objectives of this study were to determine (i) the usefulness of serial assessment of mammary gland electrolytes concentrations and correspondent pH to detect impending parturition in jennies; and (ii2) the associations between mammary gland secretions, and gestation length, foal sex, maternal, placental, and foal birth weights. Multiparous jennies (n = 37) were monitored daily from 350 to 355 days of gestation until parturition. The pH of mammary gland secretions was assessed daily with a hand-held device. Aliquots of mammary secretions were frozen daily and then retrospectively assessed for electrolyte concentrations (Ca²⁺, Mg²⁺, K⁺, and Na⁺) with an automated analyzer from five days until the last sampling pre-partum. Mammary gland electrolytes and pH were analyzed with mix-models. The gestational length, newborn, maternal, and fetal membranes weights were analyzed with t-test grouped by foal's sex. Associations across all variables were assessed with Pearson's coefficient of correlation. Sensitivity, specificity, and negative predictive value (NPV) and positive predictive values (PPV) were evaluated for pH (≤ 6.4), Ca²⁺ (>10 mmol/L), and a combination of both. Each jenny had pH profiles assessed visually and classified as fast pH drop (1), slow pH drop (2), and alkaline pH (3) as previously described for horses. The overall gestation length was 374 ± 8.7 days, ranging from 357 to 390 days. There were no differences for gestation lengths for jennies delivering colts (374 ± 2.1 range 357-385 days), versus the ones delivering fillies (373 ± 2.3 range 358-390 days) (P > .05). Of all the foals, there were 61.8% colts and 38.2% fillies. The ratio of foal birthweight with the dam's bodyweight was 9.7%, and the ratio with fetal membranes was 11%. The majority of parturitions happened during the night (91.9%). There was a significant reduction in Na⁺ and an increase in Ca²⁺, Mg²⁺, and K⁺ concentrations leading to foaling. The pH showed a 90% sensitivity for foaling within 24 hours, whereas the specificity was 70%, and the PPV and NPV values were 40% and 97%. Of interest, Ca²⁺ (>10 mmol/l) displayed a sensitivity and specificity of 71% and 85%, whereas the PPV and NPV were 72% and 84%. In the present study, jennies exhibited profiles 1 to 3 as previously described for mares. Herein, 65% of the jennies displayed profile 2 and foaled with a mean acidic pH of 6.4 ± 0.02. Conversely, 32% of the jennies showed a fast reduction in the pH of mammary secretion (profile 1) from day -1 (7.3 ± 0.2) to the day of foaling with an average pH of 6.6 ± 0.08. One jenny foaled with high and alkaline pH (i.e., 7.5). There were weak and negative correlations between pH and Ca²⁺, Mg²⁺, and K⁺ (P < .05). In addition, Ca²⁺ displayed a weak but significant correlation with Mg²⁺, Na⁺, and K⁺. In conclusion, daily pH measurements of the mammary gland secretions can predict foaling in jennies, whereas Ca²⁺ was not as useful. Contrary to horses that most mares present a fast pH profile, most jennies showed a slow pH profile. The sex of foal did not affect the gestational length and fetal/maternal and fetal membrane proportions in donkeys.

The Potential for New Donkey Farming Systems to Supply the Growing Demand for Hides

The demand for donkey hides for ejiao, a Traditional Chinese Medicine, has resulted in rapidly increasing prices for donkey hides and donkeys. This has put pressure on donkey populations globally and has implications for donkey welfare and the livelihoods of those who rely on donkeys as working animals. The aim of the research was to explore the feasibility of setting up new donkey farming systems to supply the rising demand for ejiao using a system dynamics model of donkey production. Results show that the size of the initial female breeding herd, reproductive performance, age of reproduction, percentage of female births and average breeding life of donkeys are key variables affecting the time to build up the donkey population to supply the demand for hides, which will be at least ten to fifteen years. The implications of this are: (i) prices for donkey hides will continue to increase, (ii) companies producing ejiao will use other ingredients, (iii) China will continue to source donkey hides from around the world, and (iv) there will be continued theft and illegal trade of donkeys and concerns for rural households reliant on donkeys for their livelihoods and adverse impacts on donkey welfare.