RESUMEN
The aim of the present study was to characterise key enzymes involved in polyunsaturated fatty acid (PUFA) synthesis in the testis and epididymis collected from 2-year-old healthy warmblood stallions (n=10). The mRNA expression of fatty acid synthase, the Δ9-, Δ6-, Δ5- and Δ4-desaturases and elongases 6, 5 and 2 (encoded by the fatty acid synthase (FASN), the stearoyl-CoA desaturase (SCD), the fatty acid desaturase 2 (FADS2), the fatty acid desaturase 1 (FADS1), the delta 4-desaturase, sphingolipid 1 (DEGS1), ELOVL fatty acid elongase 6(ELOVL6), ELOVL fatty acid elongase 5 (ELOVL5), ELOVL fatty acid elongase 2 (ELOVL2) genes respectively) was determined in equine testis and epididymis. All enzymes were present in testicular tissue and along the epididymis, but mRNA expression differed among localisations. The protein localisation of FADS1, FADS2 and ELOVL5 was determined by immunohistochemistry. In the testes, FADS1 was expressed in the germinal cells and ELOVL5 was expressed in germinal and Leydig cells; FADS2 was not detected. In the epididymis, FADS1 and FADS2 were expressed in the principal and basal cells, whereas ELOVL5 was found only in the principal cells of the caput. All three enzymes were present in epididymal vesicles secreted by an apocrine mechanism. These results suggest active PUFA metabolism during spermatogenesis and epididymal sperm maturation in stallions.
Asunto(s)
Epidídimo/enzimología , Ácido Graso Desaturasas/metabolismo , Elongasas de Ácidos Grasos/metabolismo , Ácidos Grasos Insaturados/biosíntesis , Caballos , Testículo/enzimología , Animales , delta-5 Desaturasa de Ácido Graso , Ácido Graso Desaturasas/genética , Elongasas de Ácidos Grasos/genética , Regulación Enzimológica de la Expresión Génica , MasculinoRESUMEN
The importance of the amino acid L-arginine (ARG) for conceptus growth and litter size has been demonstrated in various species. L-arginine is part of embryo-derived polyamines, a substrate for nitric oxide synthase and stimulates protein synthesis by the embryo. In the present study, we have investigated whether dietary L-arginine supplementation stimulates early conceptus growth in mares. Warmblood mares with singleton pregnancies received either an arginine-supplemented diet (approximately 0.0125% of body weight, n = 12) or a control diet (n = 11) from days 15 to 45 after ovulation. Diameter of the embryonic vesicle (days 14, 17, 20 of pregnancy) and size of the embryo respective foetus (length and maximal diameter, days 25-45 of pregnancy at 5-day intervals) were determined by transrectal ultrasound. At foaling, weight and size of the foal and the placenta were determined. Blood for determination of equine chorionic gonadotrophin (eCG) and progestin concentrations was collected repeatedly. Neither eCG nor progestin concentration in plasma of mares differed between groups at any time. No effects of arginine treatment on diameter of the embryonic vesicle between days 14 and 20 of pregnancy were detected. Diameter of the embryo/foetus on days 40 to 45 of pregnancy strongly tended to be enhanced by arginine supplementation (p = 0.06). Weight and size of neither the foal nor placenta at birth differed between groups. In conclusion, L-arginine supplementation was without negative effects on early equine embryos and may support embryonic growth at the beginning of placentation.
Asunto(s)
Arginina/administración & dosificación , Suplementos Dietéticos , Caballos/fisiología , Placentación , Preñez , Animales , Estudios de Casos y Controles , Desarrollo Embrionario , Femenino , Ovulación , EmbarazoRESUMEN
Observation of preparturient mares is labour-intensive and time requirements would be reduced with automated monitoring systems. Recently, small-size accelerometers have become available. We followed the hypothesis that increased restlessness in mares shortly before the expulsive stage of labour can be detected with such accelerometers. Accelerometers were attached medioventrally to the halter of eight late pregnant mares. To evaluate an influence of accelerometer position, in one mare two additional accelerometers were attached close to the mandibular and atlanto-occipital joints. Accelerometers were programmed to send 600 signals/min (10 Hz). Signals were recorded continuously and, for evaluation, four intervals of 30-min duration on day 4 before foaling and the last 2 hr before rupture of the allantochorion at foaling were selected. Signal detection was influenced by position of the accelerometer on the mares' halter. The highest signal detection rate was reached with the accelerometer in the lateral and dorsal position but differences of accelerations measured by the system differed neither between sensor positions nor between time intervals 4 days before foaling. Differences of accelerations increased from 120 min before foaling until birth of the foal (p < 0.001) and this increase was most pronounced during the last 30-20 min before birth of the foal (p < 0.001). Technical improvements and a foaling specific algorithm are required to improve the accuracy to predict foaling. Even if this preliminary study included only a small number of mares, results demonstrate that accelerometers could be an important component of birth alert systems in horses in the future.
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Acelerometría , Ritmo Circadiano , Caballos , Resultado del Embarazo/veterinaria , Preñez , Animales , Femenino , Monitoreo Fisiológico/métodos , Proyectos Piloto , EmbarazoRESUMEN
Early pregnancy loss is a major reason for low reproductive efficiency in the horse. In humans and mice, low numbers of regulatory T cells (Treg cells) are linked to miscarriage. The percentage of Treg cells in oestrous mares at the start of the breeding season was evaluated in relation to the outcome of subsequent pregnancy. For identification and quantification of Treg cells, a highly sensitive and specific qPCR assay targeting the Treg-specific demethylated region in the equine forkhead box transcription factor (FOXP3) gene was established. In a total of 108 mares, pregnancy was followed until detection of early pregnancy loss (n=17), abortion without identification of an infectious or apparent cause (n=9) or birth of a viable foal (n=82). Measured Treg-cell levels did not significantly differ between mares that conceived (82%; 1.50±0.04%) or did not get pregnant (18%; 1.45±0.10%). The Treg-cell percentage at oestrus before breeding was significantly different (P<0.05) between mares that either underwent early pregnancy loss up to Day 40 of pregnancy (1.29±0.07%) and mares that aborted (1.61±0.15%) or gave birth to a live foal (1.52±0.05%). These results suggest that low levels of Treg cells in mares can contribute to pregnancy loss up to Day 40 after ovulation.
Asunto(s)
Pérdida del Embrión/sangre , Pérdida del Embrión/patología , Caballos , Linfocitos T Reguladores/patología , Animales , Cruzamiento , Pérdida del Embrión/inmunología , Femenino , Fertilidad/inmunología , Edad Gestacional , Caballos/sangre , Caballos/inmunología , Inseminación Artificial/veterinaria , Recuento de Linfocitos , Paridad , EmbarazoRESUMEN
The microbiome plays a significant role in shaping the health and functioning of the systems it inhabits. The seminal microbiome of stallions has implications for the health of the reproductive tract, sperm quality during preservation and antibiotic use in semen extenders. Diverse bacteria are present on the external genital tract and a mix of commensal microorganisms populates various parts of the reproductive tract, influencing the seminal bacterial content. Other sources of bacteria include the environment, semen collection equipment, and personnel. The bacterial load can adversely affect sperm quality and fertility, particularly in artificial insemination, where semen is extended and stored before use. Antibiotics are frequently used to inhibit bacterial growth, but their effectiveness varies depending on the bacterial strains present. The aim of this study was to assess the bacterial diversity in semen from 37 healthy stallions across three European nations (Germany, Portugal, and Sweden) using 16S sequencing. Semen samples were collected from individual stallions at three AI centers; DNA extraction, sequencing, and bioinformatic analysis were performed. Differences in bacterial diversity among the stallions were seen; although bacterial phyla were shared across the regions, differences were observed at the genus level. Climate, husbandry practices, and individual variability likely contribute to these differences. These findings underscore the importance of tailoring antibiotic strategies for semen preservation based on regional bacterial profiles. The study presents a comprehensive approach to understanding the intricacies of the stallion seminal microbiome and its potential implications for reproductive technologies and animal health.
Asunto(s)
Bacterias , ARN Ribosómico 16S , Semen , Animales , Masculino , Caballos/microbiología , Semen/microbiología , Bacterias/aislamiento & purificación , Bacterias/clasificación , Bacterias/genética , ARN Ribosómico 16S/genética , Microbiota , Suecia , Portugal , AlemaniaRESUMEN
In horses, blue LED light directed at one eye of pregnant mares shortens gestation length and results in the birth of foals with lower wither heights, similar weight and reduced hair length compared to controls. In this study, we have therefore analysed postnatal development of foals born to either blue LED light-treated (n = 20) or control mares (n = 20). Size, weight and hair coat changes were determined for 1 year and heart rate, heart rate variability (HRV) and selected haematology parameters for 1 month. Haematocrit decreased (P < .001) and leukocyte and lymphocyte counts increased (P < .001) but none of the parameters differed between groups. Heart rate (P < .001) and HRV (P < .01) increased until day 6 but did not differ between groups, indicating that foals born to blue LED light-treated mares were mature and healthy. The guard hair was shorter in foals born to treated mares compared to control foals at birth (P < .001) but no differences in hair coat length were observed beyond the age of 2 months. At birth and 6 days thereafter, wither height (P < .01) and elbow to carpus distance (P < .05) of control foals were increased relative to foals born to blue LED light-treated mares. Height differences decreased over time and and for elbow-to-carpus distance there was a time x group interaction (P < .005) In conclusion, blue LED light treatment of pregnant mares is without detrimental effects on postnatal foal growth and development.
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Luz , Parto , Animales , Femenino , Cabello , Caballos , EmbarazoRESUMEN
Economic losses due to dystocia or neonatal death as well as animal welfare and ethical concerns demand a reliable prediction of parturition with the aim to improve survival of the dam and her offspring. In this review, estimation of gestational age by ultrasound and prediction of parturition based on clinical signs, behaviour changes and changes in body temperature, composition of mammary gland secretions as well as hormonal changes are discussed in comparison between horses and cattle. Based on the physiological changes associated with the end of gestation and onset of labor, several systems and methods to predict parturition in horses and cattle have been developed. Physiological differences related to breed, maternal age and parity, pathological changes due to intrauterine growth retardation, placental problems or general illness of the dam but also housing and management systems bias a reliable prediction of parturition. This may be acceptable in cattle as long as birth alarm systems give satisfying results at herd level. The situation is different in the horse where the economic and emotional value of an individual mare and her foal usually reaches different dimensions than in cows. The possibilities for prediction of parturition can thus be discussed together, the consequences, however, may differ considerably between the two species.
Asunto(s)
Bovinos/fisiología , Caballos/fisiología , Monitoreo Fisiológico/veterinaria , Parto/fisiología , Preñez , Animales , Femenino , Monitoreo Fisiológico/métodos , Embarazo , Preñez/sangreRESUMEN
Cortisol is involved in the initiation of parturition and we hypothesized that increased maternal cortisol release advances the onset of foaling. Transport is a stressor for horses and induces an increase in cortisol release. To determine stress effects on the time of foaling, late-pregnant mares were transported by road for 3 hours (n = 12) or remained in their stable as controls (n = 4). Starting on day 325 of gestation, saliva and blood samples were taken for cortisol and progestin analysis, respectively. Fetomaternal electrocardiograms were recorded repeatedly. Mares were checked for impending parturition and changes in precolostrum pH. When pH decreased to 6.5, mares were either transported or left untreated. After birth, saliva was collected repeatedly from mares and their foals and heart rate (HR) was recorded. Foals were checked for maturity and health. Gestation length was 337 ± 2 days in stressed and 336 ± 2 days in control mares. Cortisol concentration increased from 3.3 ± 0.9 to 8.4 ± 0.8 ng/mL in transported mares (P < .001) and remained constant in controls. Maternal HR and heart rate variability (HRV) did not differ between groups and neither fetal HR nor HRV changed in response to transport. In transported mares, time from precolostrum decrease to parturition was shorter (40 ± 10 hours) than the respective time in controls (134 ± 49 hours, P < .01). Neither duration of foaling nor times to first standing and suckling of foals or the postnatum increase in HR and decrease in HRV differed between groups. In conclusion, transport-induced maternal cortisol release may have advanced the onset of foaling.
Asunto(s)
Hidrocortisona , Parto , Animales , Femenino , Frecuencia Cardíaca Fetal , Caballos , Embarazo , Progestinas , SalivaRESUMEN
Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland (n = 6), Haflinger (n = 8), and Warmblood pregnancies (n = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares (p < 0.05). Progestin (p < 0.001) and cortisol (p < 0.05) concentration was highest in full-size mares. Progestin concentration decreased towards parturition (p < 0.001) while cortisol concentration increased (p < 0.01). Maternal heart rate increased before foaling with the most pronounced increase in small mares (p < 0.001). The HRV increased during foaling and decreased when delivery was completed (p < 0.001). Changes were most pronounced in full-size mares (p < 0.001). Atrio-ventricular blocks regularly occurred in parturient full-size mares but only occasionally in medium-size and small mares (time p < 0.05, time × group p < 0.05). This may reflect breed differences in cardiovascular efficiency. Fetal heart rate decreased towards birth (p < 0.001) with the most pronounced decrease in full-size horses (p < 0.01). Fetal HRV showed no consistent changes before birth but increased when the foal was born (p < 0.001), this increase being most pronounced in full-size foals (p < 0.05). In conclusion, this study demonstrates both similarities and differences in peripartum endocrine and cardiac changes in horses of different size.
RESUMEN
This review summarizes current knowledge on stress-like responses in parturient animals and their role for the onset and fine-tuning of parturition. The antepartum maternal cortisol increase is part of the endocrine changes that initiate parturition but a further increase in cortisol release during labor indicates a stress response. During the last minutes of delivery, sinus arrhythmias occur in 80% of foaling mares and 60% of calving cows. Expulsion of the neonate is thus characterized by parasympathetic dominance. In late-pregnant cows transported by road, cortisol concentrations increased but relations between transport stress and abortion remain unclear. In mares, transport not only elicited a stress response but also advanced the time of foaling. Transferring parturient rats, mice and pigs after birth of the first pup or piglet, respectively, to a stressful environment prolonged the time until delivery of the next littermate. In rats and pigs, this was caused by an increased opioidergic tone that restrained oxytocin release. In mice, a stress-induced delay of subsequent deliveries was caused by increased sympathoadrenal activity. When foaling mares were transferred to an uncomfortable stable at fetal membrane rupture, time until complete birth of the foal was doubled. As in mice, increased sympathetic activity was the mechanism delaying the progress of foaling. An increased sympathetic activity is also present in parturient cows disturbed during an early stage of calving. In equine and bovine neonates, the immediate postnatal period is characterised by high sympathetic activity and an increase in cortisol concentration, indicating a pronounced stress-like response.
Asunto(s)
Animales Domésticos , Parto/fisiología , Preñez , Estrés Fisiológico/fisiología , Aborto Veterinario/etiología , Animales , Animales Domésticos/clasificación , Animales Domésticos/fisiología , Bovinos , Femenino , Caballos , Ratones , Embarazo , Ratas , PorcinosRESUMEN
Stress at foaling has been demonstrated to delay birth. In this study, we followed the hypothesis that even a short delay of foaling increases catecholamine and cortisol release in foals, induces acidosis and impairs neonatal adaptation. Foaling was prolonged for 5â¯min by transferring mares to an unfamiliar environment at rupture of the allantochorion (group delay, nâ¯=â¯6) while control mares (nâ¯=â¯5) were left undisturbed. In their foals, times from birth to first standing and first suckling, heart rate, heart rate variability (HRV) and salivary cortisol concentration were analysed. Blood for analysis of epinephrine, norepinephrine, hematology and blood gases was collected directly and 30â¯min after birth. Statistical comparisons were made by repeated measures ANOVA. Times to first standing and suckling did not differ between groups. Fetal heart rate remained unchanged during birth and increased within 15â¯min postnatum (pâ¯<â¯0.001) while HRV decreased during the first hour of life in foals of both groups (pâ¯<â¯0.05). Immediately after birth, actual base excess was lower in foals with delayed birth than in control foals (pâ¯<â¯0.05). Epinephrine concentration immediately after birth was higher in group delay foals and increased from 0 to 30â¯min after birth in control foals (time pâ¯<â¯0.001, time x group pâ¯=â¯0.001). Cortisol concentration peaked at 1â¯h after birth in both groups (pâ¯<â¯0.001). Leukocyte and PMN count decreased from 0 to 30â¯min after birth (pâ¯<â¯0.001). In conclusion, a 5-min delay at foaling affected epinephrine release and acid base balance, but was without further effect on neonatal adaptation.
Asunto(s)
Animales Recién Nacidos/fisiología , Caballos/fisiología , Estrés Fisiológico , Equilibrio Ácido-Base , Animales , Animales Recién Nacidos/metabolismo , Epinefrina/sangre , Femenino , Frecuencia Cardíaca , Hidrocortisona/metabolismo , Norepinefrina/sangre , EmbarazoRESUMEN
Mares usually give birth when they perceive their environment as safe and therefore disturbance at foaling may inhibit labor. In this study, foaling mares were transferred to an unfamiliar environment at rupture of the allantochorion (stress, nâ¯=â¯6) or were left undisturbed (control, nâ¯=â¯5). The progress of foaling, heart rate, heart rate variability (HRV) and plasma catecholamine, oxytocin and cortisol concentration were determined. In stressed mares, time from rupture of the allantochorion to appearance of the fetal feet (5.3⯱â¯1.1 vs. 1.6⯱â¯0.4â¯min) and total length of fetal expulsion were longer than in controls (both pâ¯<â¯0.05). Heart rate decreased during the expulsive phase of foaling in control mares (pâ¯<â¯0.01) but increased transiently in stressed mares. Heart rate calculated as percentage of the baseline was higher in stressed than in control mares (pâ¯=â¯0.05). HRV variables SDRR (standard deviation of the beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat differences) increased during foal expulsion (SDRR pâ¯<â¯0.01 and RMSSD pâ¯<â¯0.05). The increase in HRV was delayed in stressed compared to control mares (SDRR and RMSSD time x group pâ¯<â¯0.05). Plasma epinephrine and norepinephrine concentrations calculated as area under the curve for the expulsive phase of foaling were higher in stressed than control mares (pâ¯<â¯0.05). Concentrations of oxytocin and cortisol were elevated during foal expulsion (both pâ¯<â¯0.001) but not different between groups. In conclusion, disturbance of mares during expulsion of the foal prolonged foaling. This effect is most likely mediated via increased sympathetic activity and not inhibition of oxytocin release.
Asunto(s)
Caballos/fisiología , Parto , Estrés Fisiológico , Animales , Catecolaminas/sangre , Membrana Corioalantoides , Epinefrina/sangre , Femenino , Frecuencia Cardíaca , Hidrocortisona/sangre , Trabajo de Parto Inducido/veterinaria , Norepinefrina/sangre , Oxitocina/sangre , Embarazo , Factores de TiempoRESUMEN
In mares, foaling is associated with changes in hematology, plasma electrolytes, blood pressure and heart rate and it has been hypothesized that these are induced by oxytocin. To test this hypothesis, mares (n = 8-14/group) were treated with oxytocin (OT; 20 I.U.) or saline (CON) at 1 h (test A) and 12 h after foaling (test B) and during first postpartum diestrus (test C). Heart rate, heart rate variability (HRV), atrioventricular blocks, salivary cortisol concentration, blood pressure, plasma electrolytes and blood count were determined. Heart rate decreased from test A to C (P < 0.001) but at no time differed between groups. The HRV, blood pressure and occurrence of atrioventricular blocks did not change in response to oxytocin. Cortisol concentration decreased from test A to C (P < 0.001). Oxytocin induced a cortisol release in test B (time x treatment P < 0.001, time x test P < 0.001). Plasma sodium and chloride concentrations decreased from test A to C (P < 0.001) but did not differ between groups. In test A, potassium concentration increased in CON but not OT mares (time P < 0.01, time x test P < 0.01, time x treatment P < 0.05). Polymorphnuclear cell (PMN) numbers in blood decreased from test A to C (P < 0.001) while lymphocytes increased (P < 0.05). At no time PMN and lymphocytes differed between groups. Oxytocin treatment had no effect on skin temperature. In conclusion, except for a limited effect on cortisol release, oxytocin was without effect and the hypothesis of oxytocin-induced alterations in cardiac parameters, plasma electrolytes and hematology of foaling mares was not verified.
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Electrólitos/sangre , Corazón/efectos de los fármacos , Caballos/fisiología , Oxitocina/farmacología , Parto/efectos de los fármacos , Animales , Arritmias Cardíacas/etiología , Presión Sanguínea/efectos de los fármacos , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Hidrocortisona/sangre , Parto/fisiología , EmbarazoRESUMEN
In the present study we have evaluated a possible stress reaction in response to two different PGF2α analogs-luprostiol and D-cloprostenol--and their effects on estrous cycle characteristics. In a cross-over-design eight mares received in alternating order either luprostiol (Treatment LUP; 3.75 mg im), D-cloprostenol (Treatment CLO; 22.5µg im) or saline (Treatment CON; NaCl 0.9% 0.5ml im) on day 8 after ovulation. Injection of either LUP or CLO, but not of CON resulted in a significant decline of progesterone concentration in plasma to baseline concentrations within two days (time: p<0.001, treatment: p<0.01, time × treatment: p<0.05). The treatment to ovulation interval was significantly shorter in LUP and CLO than in CON cycles (LUP: 9.4 ± 0.4 d; CLO: 9.4 ± 1.3 d; CON: 16.1 ± 0.8 d; p<0.001). Injection of either LUP or CLO, but not of CON significantly increased salivary cortisol concentration (immediately before injection: CON 1.3 ± 0.2, LUP 1.4 ± 0.3, CLO 1.4 ± 0.3 ng/ml; 60 min after injection: CON 1.0 ± 0.3, LUP 8.0 ± 1.4, CLO 4.2 ± 0.7 ng/ml; time: p<0.01, treatment: p<0.001, time × treatment: p<0.001). Heart rate decreased over time (p<0.05) independent of treatment and no changes in heart rate variability were detected. Injection of the PGF2α analogs CLO and LUP reliably induced luteolysis and apart from a transient increase in salivary cortisol concentration no signs of a physiological stress response or apparent side effects occurred.
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Cloprostenol/farmacología , Dinoprost/agonistas , Luteólisis/efectos de los fármacos , Prostaglandinas F Sintéticas/farmacología , Animales , Conducta Animal/efectos de los fármacos , Cloprostenol/efectos adversos , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Caballos/fisiología , Fase Luteínica/efectos de los fármacos , Fase Luteínica/fisiología , Prostaglandinas F Sintéticas/efectos adversos , Temperatura Cutánea/efectos de los fármacos , Estrés Fisiológico/efectos de los fármacosRESUMEN
In this study, peripartum changes in complete blood count, plasma electrolyte concentrations, blood pressure, heart rate, and heart rate variability (HRV) were determined in pregnant Warmblood mares (n = 10). Blood was collected from Days 245 to 330 of gestation (phase A), 2Days 3 to 1 before foaling (phase B), repeatedly within 12 hours after foaling (phase C), and on Days 1 to 3 postpartum (phase D). On the same days as blood collection, blood pressure and cardiac beat-to-beat intervals were measured and time domain HRV variables were calculated. Blood pressure decreased during the past 3 months of gestation, reached a nadir at foaling and increased rapidly thereafter (P < 0.001). Heart rate increased in phase A, reached a maximum in phase B, and decreased directly after foaling (P < 0.001) while HRV increased transiently after foaling (P < 0.001). The number of polymorphonuclear granulocytes was higher during phases B, C, and D than that during phase A (P < 0.001) and total leukocyte numbers peaked in phase C (P < 0.001). Erythrocyte counts and hematocrit increased immediately after foaling with a rapid decrease thereafter (P < 0.001), while plasma total protein was highest 1 hour after foaling (P < 0.001). Sodium and chloride concentrations increased from phases A to C and decreased in phase D (P < 0.001). Calcium concentrations were lowest immediately after foaling. In conclusion, changes in cardiovascular function and a transient hemoconcentration occur in peripartum mares. These changes may favor adequate uterine perfusion.
Asunto(s)
Recuento de Células Sanguíneas/veterinaria , Presión Sanguínea/fisiología , Frecuencia Cardíaca/fisiología , Caballos/fisiología , Periodo Periparto/fisiología , Preñez , Animales , Electrólitos/sangre , Femenino , Embarazo , Preñez/fisiologíaRESUMEN
Increased cortisol release in parturient cows may either represent a stress response or is part of the endocrine changes that initiate calving. Acute stress elicits an increase in heart rate and decrease in heart rate variability (HRV). Therefore, we analyzed cortisol concentration, heart rate and HRV variables standard deviation of beat-to-beat interval (SDRR) and root mean square of successive beat-to-beat intervals (RMSSD) in dairy cows allowed to calve spontaneously (SPON, n = 6) or with PGF2α-induced preterm parturition (PG, n = 6). We hypothesized that calving is a stressor, but induced parturition is less stressful than term calving. Saliva collection for cortisol analysis and electrocardiogram recordings for heart rate and HRV analysis were performed from 32 hours before to 18.3 ± 0.7 hours after delivery. Cortisol concentration increased in SPON and PG cows, peaked 15 minutes after delivery (P < 0.001) but was higher in SPON versus PG cows (P < 0.001) during and within 2 hours after calving. Heart rate peaked during the expulsive phase of labor and was higher in SPON than in PG cows (time × group P < 0.01). The standard deviation of beat-to-beat interval and RMSSD peaked at the end of the expulsive phase of labor (P < 0.001), indicating high vagal activity. Standard deviation of beat-to-beat interval (P < 0.01) and RMSSD (P < 0.05) were higher in SPON versus PG cows. Based on physiological stress parameters, calving is perceived as stressful but expulsion of the calf is associated with a transiently increased vagal tone which may enhance uterine contractility.
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Glándulas Suprarrenales/fisiología , Bovinos/fisiología , Dinoprost/farmacología , Trabajo de Parto Inducido , Parto , Estrés Fisiológico/fisiología , Sistema Nervioso Simpático/fisiología , Animales , Peso al Nacer , Industria Lechera , Femenino , Frecuencia Cardíaca/fisiología , Homeostasis/fisiología , Hidrocortisona/análisis , Hidrocortisona/metabolismo , Trabajo de Parto Inducido/métodos , Trabajo de Parto Inducido/veterinaria , Parto/efectos de los fármacos , Parto/metabolismo , Embarazo , Nacimiento Prematuro/metabolismo , Nacimiento Prematuro/fisiopatología , Saliva/química , Saliva/metabolismoRESUMEN
This study tested the hypothesis of gestational age affecting fetal cardiac activity and the stress response at birth. Heart rate (HR), heart rate variability variables, SD of the beat-to-beat interval and root mean square of successive beat-to-beat differences, and postnatal salivary cortisol concentration were studied in calves born at term (Term, n = 7, gestation length 286.3 ± 2.1 days) or after induction of parturition (Preterm, n = 7, gestation length 279.6 ± 0.2 days). Observation periods covered the last month of gestation (phase A), the last hours before birth including the first stage of labor (phase B), and the neonatal period (phase C). Fetal HR decreased in phase A (P < 0.001) and did not differ between groups. During phase B, HR increased (P < 0.05) and was higher in Preterm than in Term calves in phases B (P < 0.05) and C (P < 0.01). In Term calves, heart rate variability increased from Day 6 until birth (P < 0.05). At birth, SD of the beat-to-beat interval was higher in Term than in Preterm calves (P < 0.01). On Day 1 after birth (phase C), HR accelerations were more frequent in Term than Preterm calves (P < 0.01), whereas decelerations were more frequent in Preterm calves (P < 0.05). Cortisol concentration increased postnatally (P < 0.001) and was correlated with gestation length (r ≥ 0.68, P < 0.01). Because of a certain degree of immaturity, the ability to cope with the stress of birth may be impaired in calves born 1 week before term.
Asunto(s)
Animales Recién Nacidos/fisiología , Bovinos , Edad Gestacional , Frecuencia Cardíaca Fetal/fisiología , Frecuencia Cardíaca/fisiología , Estrés Fisiológico/fisiología , Animales , Peso al Nacer , Femenino , Hidrocortisona/análisis , Trabajo de Parto Inducido/veterinaria , Trabajo de Parto/fisiología , Parto/fisiología , Embarazo , Saliva/químicaRESUMEN
Transrectal palpation and ultrasonography of the genital tract in mares are first-day skills for equine veterinarians. In this study, the learning outcome in equine gynecology after four times training on horses (group H4, n = 8), training on horses once (group H1, n = 9), and four times simulator-based training (group Sim, n = 8) was assessed in third-year veterinary students with two tests in live mares 14 days apart. The students of group H4 always scored better for transrectal palpation than students of group Sim and H1 (P < 0.05). Overall, the students reached better results for palpating the left versus the right ovary (P < 0.001), but group H1 students were least successful in obtaining correct ovarian findings (P < 0.05 vs. both other groups). Students' self-assessment reflected test results with palpation of the right ovary experienced as most difficult for group H1 students (P < 0.01 vs. both other groups). Groups did not score differentially for ultrasound examinations. Sim students were nearly as successful in transrectal palpation of the genital tract in mares as H4 students, and for most parameters assessed, they performed better than H1 students. After training four times on horses, students scored best but nevertheless the overall effect of intensive training was limited. Repeated simulator-based training is a useful tool to prepare veterinary students for transrectal palpation of the genital tract in mares and is more effective than one training session on horses.
Asunto(s)
Educación en Veterinaria/métodos , Caballos , Entrenamiento Simulado , Animales , Tacto Rectal , Femenino , Genitales Femeninos , Ovario/diagnóstico por imagen , Examen Físico/veterinaria , Ultrasonografía , Medicina VeterinariaRESUMEN
In this study, fetomaternal electrocardiograms were recorded once weekly in cattle during the last 14 weeks of gestation. From the recorded beat-to-beat (RR) intervals, heart rate and heart rate variability (HRV) variables standard deviation of the RR interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated. To differentiate between effects of lactation and gestation, pregnant lactating (PL) cows (n = 7) and pregnant nonlactating (PNL) heifers (n = 8) were included. We hypothesized that lactation is associated with stress detectable by HRV analysis. We also followed the hypothesis that heart rate and HRV are influenced by growth and maturation of the fetus toward term. Maternal heart rate changed over time in both groups, and in PL cows, it decreased with drying-off. During the last 5 weeks of gestation, maternal heart rate increased in both groups but was lower in PL cows than in PNL heifers. Maternal HRV did not change over time, but SDRR was significantly higher in PL cows than in PNL heifers, and significant interactions of group × time existed. On the basis of HRV, undisturbed pregnancies are thus no stressor for the dam in cattle. Fetal heart rate decreased from week 14 to week 1 before birth with no difference between groups. Gestational age thus determines heart rate in the bovine fetus. The HRV variables SDRR and RMSSD increased toward the end of gestation in fetuses carried by cows but not in those carried by heifers. The increase in HRV indicates maturation of fetal cardiac regulation which may be overrun by high sympathoadrenal activity in fetuses carried by heifers as suggested by their low HRV.
Asunto(s)
Bovinos/fisiología , Frecuencia Cardíaca Fetal , Frecuencia Cardíaca , Preñez/fisiología , Animales , Electrocardiografía/veterinaria , Femenino , Edad Gestacional , Lactancia , EmbarazoRESUMEN
External and internal stressors prolong parturition in different species. At parturition, sympathoadrenal activation should be avoided because an increased sympathetic tone may cause uterine atonia via ß2-receptors. We hypothesized that at physiological parturition, horses are under parasympathetic dominance, and stress-response mechanisms are not activated during delivery of the foal. To evaluate stress responses, heart rate, heart rate variability, catecholamines, and cortisol were analyzed in mares (n = 17) throughout foaling. Heart rate decreased from 2 hours before (51 ± 1 beats/minute) to 2 hours after delivery (41 ± 2 beats/minute; P < 0.05). Heart rate variability variables, standard deviation of the beat-to-beat interval, and root mean square of successive beat-to-beat differences, changed over time (P < 0.05) with the highest values within 15 minutes after delivery. The number of mares with atrioventricular blocks and the number of atrioventricular blocks per mare increased over time (P < 0.01) and were significantly elevated from 15 minutes before to 45 minutes after birth of the foal. Salivary cortisol concentrations increased to a maximum at 30 minutes after delivery (25.0 ± 3.4 ng/mL; P < 0.01). Plasma epinephrine and norepinephrine concentrations showed significant fluctuations from rupture of the allantochorion to expulsion of the fetal membranes (P < 0.01) but were not markedly elevated at any time. In conclusion, mares give birth under high parasympathetic tone. Cortisol release during and after foaling is most likely part of the endocrine pathways regulating parturition and not a labor-associated stress response.