Stress effects on the regulation of parturition in different domestic animal species

Effect of peripartum dexamethasone treatment on farrowing outcomes and newborn piglet traits in multiparous sows

This study assessed the effects of dexamethasone treatment on farrowing performance and piglet traits in the first 5 days of life in multiparous sows, a high-risk group for stillbirths and prolonged farrowing. In this study, 185 multiparous sows (parity 4.25 ± 0.14) were selected on the day of farrowing and divided into three treatments: CON - control, without dexamethasone treatment; DexaPF - treatment with dexamethasone (20 mg im per female) at the time of copious colostrum secretion (pre-farrowing); and DexaFO - treatment with dexamethasone (20 mg im per female) when the first piglet was born (farrowing onset). All sows and their litters were monitored for farrowing duration, obstetric interventions, colostrum yield and intake, newborn piglet traits, and piglet performance until 5 d of age. A subsample of 106 females (∼35 per treatment) had their blood glucose concentration checked hourly shortly after the first piglet was born until the end of farrowing. Additionally, blood samples from 42 litters were collected for immunocrit evaluation. The results showed no differences regarding farrowing duration (CON = 258.02 ± 13.81 min; DexaPF = 251.29 ± 13.60 min; DexaFO = 294.92 ± 13.89 min; P = 0.06) and obstetric intervention rates among treatments (CON = 36.58 ± 6.78 %; DexaPF = 42.16 ± 6.89 %; DexaFO = 48.05 ± 7.08 %; P = 0.45). The blood glucose concentration during farrowing was higher in DexaPF (94.56 ± 1.57 mg/dL; P < 0.001) than in CON (73.50 ± 1.72 mg/dL) and DexaFO (87.94 ± 1.80 mg/dL). No differences were observed regarding total piglets born and born alive, stillborn, newborn piglet vitality, colostrum intake, immunocrit, colostrum yield, and glycemia and rectal temperature at 24 h of age (P ≥ 0.13). Regarding meconium staining, higher percentages of piglets born without meconium staining were observed in DexaFO (54.77 ± 5.21 %; P = 0.02) compared with CON (48.58 ± 5.26 %), and no difference was observed for the DexaPF group (53.23 ± 5.21 %). In addition, a higher unbroken umbilical cord rate was observed in DexaFO (92.41 ± 1.31 %; P < 0.01) than the CON or DexaPF (86.91 ± 1.97 % and 89.31 ± 1.67 %, respectively). However, the treatments did not affect piglet performance (weight gain and survival) until 5 d of age (P ≥ 0.15). In summary, dexamethasone treatment in periparturient multiparous sows did not improve farrowing performance and key production parameters, such as the piglet weight gain and survival up to 5 d of age.

Localization of Catecholaminergic Neurofibers in Pregnant Cervix as a Possible Myometrial Pacemaker

In eutocic labor, the autonomic nervous system is dominated by the parasympathetic system, which ensures optimal blood flow to the uterus and placenta. This study is focused on the detection of the quantitative presence of catecholamine (C) neurofibers in the internal uterine orifice (IUO) and in the lower uterine segment (LUS) of the pregnant uterus, which could play a role in labor and delivery. A total of 102 women were enrolled before their submission to a scheduled cesarean section (CS); patients showed a singleton fetus in a cephalic presentation outside labor. During CS, surgeons sampled two serial consecutive full-thickness sections 5 mm in depth (including the myometrial layer) on the LUS and two randomly selected samples of 5 mm depth from the IUO of the cervix. All histological samples were studied to quantify the distribution of A nerve fibers. The authors demonstrated a significant and notably higher concentration of A fibers in the IUO (46 ± 4.8) than in the LUS (21 ± 2.6), showing that the pregnant cervix has a greater concentration of A neurofibers than the at-term LUS. Pregnant women's mechanosensitive pacemakers can operate normally when the body is in a physiological state, which permits normal uterine contractions and eutocic delivery. The increased frequency of C neurofibers in the cervix may influence the smooth muscle cell bundles' activation, which could cause an aberrant mechano-sensitive pacemaker activation-deactivation cycle. Stressful circumstances (anxiety, tension, fetal head position) cause the sympathetic nervous system to become more active, working through these nerve fibers in the gravid cervix. They might interfere with the mechano-sensitive pacemakers, slowing down the uterine contractions and cervix ripening, which could result in dystocic labor.

Heart rate variability and behavioral alterations during prepartum period in dairy cows as predictors of calving: a preliminary study

OBJECTIVE

Parturition is crucial for dams, their calves, and cow managers. The prediction of calving time, which assists cow managers to decide on the relocation of cows to maternity pens and necessity of human supervision, is a pivotal aspect of livestock farming. However, existing methods of predicting calving time in dairy cows based on hormonal changes and clinical symptoms are time-consuming and yield unreliable predictions. Accordingly, we investigated whether heart rate variability (HRV) which is a non-invasive assessment of autonomic nervous system (ANS) activity and behavior during the prepartum period would be useful for predicting calving time in dairy cows.

METHODS

Eight pregnant cows were surveilled under electrocardiogram and video recordings for HRV and behavioral analyses, respectively. HRV parameters in time and frequency domains were evaluated. A 24-h time budget was calculated for each of six types of behavior (standing and lying with or without rumination, sleeping, and eating).

RESULTS

Heart rate on calving day is considerably higher than those recorded on the days preceding calving. Low frequency power declined, whereas high frequency power escalated on the calving day compared to the period between 24 and 48 h before calving. The time budget for ruminating while lying decreased and that while standing increased markedly on the calving day compared to those allocated on the preceding days; nonetheless, the total time budget for ruminating did not differ during the prepartum period.

CONCLUSION

We elucidated the ANS activity and behavioral profiles during prepartum period. Our results confirm that HRV parameters and behavior are useful for predicting calving time, and interestingly indicate that the time budget for ruminating while standing (or lying) may serve as a valuable predictor of calving. Collectively, our findings lay the foundation for future investigations to determine other potential predictors and formulate an algorithm for predicting calving time.

Large litters have a detrimental impact on litter performance and postpartum maternal behaviour in primiparous sows

BACKGROUND

Our previous study confirmed that large litter size adversely affects prepartum maternal hormones and behaviour, concurrently with heightened oxidative stress in primiparous sows. The purpose of this study was to examine the effect of large litter size on litter performance, postpartum maternal behaviour, salivary cortisol levels, and colostral immunoglobulin levels in sows, as well as investigate their correlations with the levels of oxidative stress parameters.

RESULTS

A total of 24 primiparous sows (Landrace[Formula: see text]Large white) and their offspring were categorised into two groups based on litter size: NORMAL (n = 8) with litter size ranging from 7 to 14 (mean 11.5[Formula: see text]2.7), and LARGE (n=16) with litter size ranging from 15 to 20 (mean 15.9[Formula: see text]1.4). All sows were housed in a group housing system during gestation and transitioned to an adaptable loose housing system (2.4[Formula: see text]2.3 m) during the farrowing and lactation periods. The nursing and carefulness behaviour of the sows was monitored over a 24-h period between 72 and 96 h after parturition. Saliva samples were collected for cortisol assay on 35, 21, and 7 days before parturition (D-35, D-21, and D-7, respectively), as well as on days 1, 7, and 28 after parturition (D1, D7, and D28, respectively). On D1, higher piglet mortality rates were observed among the LARGE group compared to the NORMAL group (p<0.01). The total and successful nursing behaviours of the sows were less frequent in the LARGE group than in the NORMAL group (p<0.05, for both), and the carefulness score of the LARGE group was also lower than that of the NORMAL group (p< 0.01). On D1, cortisol levels in LARGE sows were higher than those in NORMAL sows (p< 0.05), and for other time points (D-21, D-7, D7, and D28), cortisol levels in LARGE sows tended to be higher than those in NORMAL sows (p < 0.10, for all). Successful nursing behaviour displayed negative correlations with levels of salivary cortisol and certain oxidative stress parameters measured on D1.

CONCLUSIONS

These findings suggest that the strategy for alleviating physiological and oxidative stress during the peripartum periods could benefit potential postpartum maternal behaviour and litter performance in the sows with large litters.

The effect and mechanism of selenium supplementation on the proliferation capacity of bovine endometrial epithelial cells exposed to lipopolysaccharide in vitro under high cortisol background

Bovine endometritis severely inhibits uterine repair and causes considerable economic loss. Besides, parturition-induced high cortisol levels inhibit immune function, reduce cell proliferation, and further inhibit tissue repair. Selenium (Se) is an essential trace element for animals to maintain normal physiological function and has powerful antioxidant functions. This study investigated whether Se supplementation reduces endometrial damage and promotes tissue repair in cows with endometritis under stress and explored the underlying mechanism. Primary bovine endometrial epithelial cells were isolated and purified from healthy cows. The cells were treated with different combinations of lipopolysaccharide (LPS), cortisol, and various concentrations of Se. Data showed that LPS stimulation inhibited cell proliferation and increased cell apoptosis. High levels of cortisol further exacerbated these effects. Flow cytometry, scratch wound healing tests, and 5-ethynyl-2'-deoxyuridine (EdU) proliferation assays showed that Se supplementation promoted cell cycle progression, cell migration, and cell proliferation in the presence of LPS and cortisol. The quantitative PCR results showed that the expression of related growth factors was increased after Se supplementation. After administering various inhibitors, we further demonstrated that Se supplementation decreased the activity of glycogen synthetase kinase 3β (GSK-3β) through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway to reduce the degradation of β-catenin except the Wnt signal to promote cell proliferation. In conclusion, Se supplementation attenuated the cell damage induced by LPS at high cortisol levels and increased cell proliferation to promote uterine repair by elevating the mRNA expression of TGFB3 and VEGFA and activating the PI3K/AKT/GSK-3β/β-catenin signaling pathway.

Comparison of behavioral and physiological changes in postpartum healthy and inflammatory diseased cows

During parturition, cows often experience intense pain and stress, which increases the risk of inflammatory diseases. This study aimed to compare the postpartum health status between healthy cows and those diagnoses with inflammatory diseases by examining behavioral and heart rate (HR) variability (HRV) changes, to provide information before the onset of disease. Eight Holstein cows were used in this study. HR, parameters of HRV (low-frequency power: LF; high-frequency power: HF; LF/HF ratio, and total power) and time budget of individual maintenance behaviors (standing, recumbency, feeding, rumination while standing and lying, and sleep) were continuously recorded from 0 to 168 h postpartum. Milk and blood samples were collected daily. Cows were categorized as diseases based on the positive result of California mastitis test and/or serum haptoglobin concentration that exceeded 50 μg/ml after all blood samples have been collected. Compared to healthy individuals (n = 3), diseased cows (n = 5) exhibited higher HR, LF/HF, and lower total power (p < 0.05), suggesting the dominance of the sympathetic nervous system in cows with inflammatory diseases. Additionally, diseased cows showed an increased standing time budget and reduced recumbency (p < 0.05), which may be a behavioral strategy in response to discomfort from inflammation.

Transcriptome analysis of the Bactrian camel (Camelus bactrianus) reveals candidate genes affecting milk production traits

BACKGROUND

Milk production traits are complex traits with vital economic importance in the camel industry. However, the genetic mechanisms regulating milk production traits in camels remain poorly understood. Therefore, we aimed to identify candidate genes and metabolic pathways that affect milk production traits in Bactrian camels.

METHODS

We classified camels (fourth parity) as low- or high-yield, examined pregnant camels using B-mode ultrasonography, observed the microscopic changes in the mammary gland using hematoxylin and eosin (HE) staining, and used RNA sequencing to identify differentially expressed genes (DEGs) and pathways.

RESULTS

The average standard milk yield over the 300 days during parity was recorded as 470.18 ± 9.75 and 978.34 ± 3.80 kg in low- and high-performance camels, respectively. Nine female Junggar Bactrian camels were subjected to transcriptome sequencing, and 609 and 393 DEGs were identified in the low-yield vs. high-yield (WDL vs. WGH) and pregnancy versus colostrum period (RSQ vs. CRQ) comparison groups, respectively. The DEGs were compared with genes associated with milk production traits in the Animal Quantitative Trait Loci database and in Alashan Bactrian camels, and 65 and 46 overlapping candidate genes were obtained, respectively. Functional enrichment and protein-protein interaction network analyses of the DEGs and candidate genes were conducted. After comparing our results with those of other livestock studies, we identified 16 signaling pathways and 27 core candidate genes associated with maternal parturition, estrogen regulation, initiation of lactation, and milk production traits. The pathways suggest that emerged milk production involves the regulation of multiple complex metabolic and cellular developmental processes in camels. Finally, the RNA sequencing results were validated using quantitative real-time PCR; the 15 selected genes exhibited consistent expression changes.

CONCLUSIONS

This study identified DEGs and metabolic pathways affecting maternal parturition and milk production traits. The results provides a theoretical foundation for further research on the molecular mechanism of genes related to milk production traits in camels. Furthermore, these findings will help improve breeding strategies to achieve the desired milk yield in camels.

Predicting labor onset relative to the estimated date of delivery using smart ring physiological data

The transition from pregnancy into parturition is physiologically directed by maternal, fetal and placental tissues. We hypothesize that these processes may be reflected in maternal physiological metrics. We enrolled pregnant participants in the third-trimester (n = 118) to study continuously worn smart ring devices monitoring heart rate, heart rate variability, skin temperature, sleep and physical activity from negative temperature coefficient, 3-D accelerometer and infrared photoplethysmography sensors. Weekly surveys assessed labor symptoms, pain, fatigue and mood. We estimated the association between each metric, gestational age, and the likelihood of a participant's labor beginning prior to (versus after) the clinical estimated delivery date (EDD) of 40.0 weeks with mixed effects regression. A boosted random forest was trained on the physiological metrics to predict pregnancies that naturally passed the EDD versus undergoing onset of labor prior to the EDD. Here we report that many raw sleep, activity, pain, fatigue and labor symptom metrics are correlated with gestational age. As gestational age advances, pregnant individuals have lower resting heart rate 0.357 beats/minute/week, 0.84 higher heart rate variability (milliseconds) and shorter durations of physical activity and sleep. Further, random forest predictions determine pregnancies that would pass the EDD with accuracy of 0.71 (area under the receiver operating curve). Self-reported symptoms of labor correlate with increased gestational age and not with the timing of labor (relative to EDD) or onset of spontaneous labor. The use of maternal smart ring-derived physiological data in the third-trimester may improve prediction of the natural duration of pregnancy relative to the EDD.

[Initiation and endocrine control of parturition in domestic mammals - Part 1]

Endocrine regulation of parturition is based on an intense exchange of signals between the fetus, placenta and mother. Apart from sheep, our knowledge of the endocrine control of parturition is still very incomplete. However, current observations suggest significant differences between the species. For the maintenance of pregnancy, progesterone (P4) is the crucial superordinate regulatory factor, although in some species, such as the horse, functions of P4 are at least partially fulfilled by other progestogens. In general, prepartum P4 withdrawal is considered a prerequisite for the onset of physiological birth. In species with exclusive (dog) or predominant (e. g., cattle, goat, pig) luteal P4 at the end of gestation, luteolysis is the crucial event. In sheep, where P4 is of placental origin prior to parturition, the prepartum P4 decline is due to a switch in placental steroid metabolism. The mechanism of prepartum progestogen withdrawal in the mare is still largely unclear. In sheep, initiation of parturition proceeds from maturation of the fetal hypothalamic-pituitary-adrenal (HPA) axis, which leads to a steep prepartum rise in fetal cortisol concentrations stimulating the collapse of placental P4 production. In cattle, fetal cortisol probably triggers luteolysis via stimulation of placental prostaglandin secretion. In several other domestic mammalian species, there is also evidence that the initiation of parturition proceeds from maturation of the fetal HPA axis. However, the functional relationships between fetal cortisol and prepartum P4 withdrawal are largely unknown in nonruminant species.

Hair cortisol concentration in postpartum dairy cows and its association with parameters of milk production

Hair cortisol concentration (HCC) is considered as an indicator for a minimally invasive assessment of long-term stress. In dairy cows, in addition to stress influences, changing physiological conditions during gestation and lactation (eg, due to varying energy requirements or fluctuating milk yield) may affect HCCs. Thus, the aim of our study was to investigate HCCs of dairy cows during different stages of lactation and to determine the relationship between milk production traits and hair cortisol levels. Samples of natural hair and regrown hair were collected from 41 multiparous Holstein Friesian cows at 100-d intervals from parturition to 300 d postpartum. All samples were analyzed for cortisol concentration and the association of HCC with milk productions traits was evaluated. Our results show that cortisol concentration in natural hair increased after parturition and was highest 200 d postpartum. Cumulative milk yield from parturition to 300 d showed moderate and positive correlation with HCC in natural hair at 300 d. There was a positive correlation between urea concentration in milk and cortisol levels in regrown hair at 200 d, and between somatic cell count in milk and HCC in natural and regrown hairs 200 d postpartum. Together, these findings suggest that physiological loads during lactation, eg, caused by metabolic stress and/or inflammation, may be associated with increased HCC levels. In addition, the results on hair color confirm previous findings in cattle that black hair has higher cortisol concentrations than white hair. Black hair therefore appears to be more suitable for hair cortisol analysis as it provides higher protection against photodegradation.

Relationship between dexamethasone treatment around parturition of primiparous sows and farrowing performance and newborn piglet traits

This study evaluated the relationship between the steroidal anti-inflammatory action of dexamethasone treatment in primiparous sows and farrowing and piglet performance in the first 5 d of life. For this purpose, 234 gilts were selected on the day of farrowing and distributed among three treatments: CON - control, without dexamethasone treatment; DexaPF - treatment with dexamethasone (20 mg im) per female at the moment of copious colostrum secretion (pre-farrowing); and DexaFO - treatment with dexamethasone (20 mg im), per female when the first piglet was born (farrowing onset). All females and their litters were evaluated regarding farrowing duration, obstetric interventions, colostrum yield and intake, newborn piglet traits, and piglet performance until 5 d of age. A subsample of 79 females (∼26 per treatment) had their blood glucose concentration evaluated hourly shortly after the first piglet was born until the end of farrowing. Additionally, blood samples from 11 litters per treatment were collected for immunocrit evaluation. As a result, faster farrowing was observed in the DexaPF treatment (188.14 min; P = 0.002) compared with CON (229.99 min) and DexaFO (221.79 min). Additionally, lower obstetric intervention rates were observed in sows treated with dexamethasone (DexaPF = 7.69%; DexaFO = 5.13%) compared with CON (19.23%; P = 0.02). The sow's blood glucose concentration during farrowing was higher in DexaPF (90.55 mg/dL) than in CON (73.15 mg/dL) and DexaFO (80.06 mg/dL) treatments (P < 0.01). Besides the effect on farrowing duration, no differences among treatments were observed regarding piglets born alive and stillbirths, newborn piglet vitality, colostrum consumption, immunocrit, and colostrum yield (P ≥ 0.17). Regarding piglet traits, higher percentages of piglets born without meconium staining and lower percentages of piglets with meconium scores 2 and 3 were observed in the groups treated with dexamethasone (DexaPF and DexaFO; P < 0.01) compared with CON. However, piglet weight gain and survival rate until 5 d of age were not affected by the treatment (P ≥ 0.61). In summary, dexamethasone treatment before farrowing onset, in primiparous sows, had the potential to reduce the farrowing duration and the necessity of obstetric intervention, but it did not affect the main productive parameters such as the occurrence of stillbirths, piglet weight gain, and survival rates until 5 d of age.

Clinical Experiences and Mechanism of Action with the Use of Oxytocin Injection at Parturition in Domestic Animals: Effect on the Myometrium and Fetuses

Oxytocin is a key hormone for parturition and maternal traits in animals. During the peripartum period, the levels of endogenous oxytocin dictate physiological events such as myometrial contractions, prostaglandin production with the subsequent increase in oxytocin receptors, and the promotion of lactation when administered immediately after birth. While this hormone has some benefits regarding these aspects, the exogenous administration of oxytocin has been shown to have detrimental effects on the fetus, such as asphyxia, meconium staining, ruptured umbilical cords, and more dystocia cases in females. This review aims to analyze the main effects of oxytocin on myometrial activity during parturition, and its potential favorable and negative administration effects reflected in the fetus health of domestic animals. In conclusion, it is convenient to know oxytocin's different effects as well as the adequate doses and the proper moment to administrate it, as it can reduce labor duration, but it can also increase dystocia.

Dam parity affects fetal growth, placental size, and neonatal metabolism in spring-born beef calves

To determine effects of dam parity on perinatal nutrient availability in beef cattle, data and samples were collected from 18 primiparous and 35 multiparous spring-calving Sim-Angus dams and their calves. Time to stand was recorded and neonatal vigor assessed. Jugular blood was collected from a subset of calves at 0 (post-standing and pre-suckling) 6, 12, 24, 48, and 72 h of age, and blood chemistry panels were completed. Expelled placentas were dissected, dried, and weighed. Prepartum maternal circulating glucose, non-esterified fatty acids (NEFA), triglycerides, and urea N were analyzed. All statistical models included the fixed effect of dam parity, and calf sex (when P ≤ 0.25) was included for calf and placental variables. Effects of sampling hour, and parity × hour were included for calf metabolites over time using repeated measures. Multiparous dams had greater body weight prepartum (P < 0.001) but similar (P = 0.25) body condition score. Maternal circulating urea N and triglycerides were greater (P ≤ 0.05) in multiparous dams pre-calving. Calves born to primiparous dams weighed 10% less (P ≤ 0.04) at birth with smaller (P ≤ 0.01) heart and abdominal girths. Cotyledonary, intercotyledonary, and total placental masses were less (P ≤ 0.05) for primiparous dams. Dam parity did not affect (P ≥ 0.58) calf time to stand, vigor score at 10 min, or rectal temperature. Serum glucose was greater (P = 0.03) at 0 h but less (P ≤ 0.04) at all other hours in calves from primiparous dams. Calves from primiparous dams had greater (P ≤ 0.02) serum NEFA at 6, 12, and 24 h although plasma triglycerides were greater (P < 0.001) at 6 h. Calves from primiparous dams had greater (P ≤ 0.04) serum urea N at 12 h and creatinine at 12 and 24 h. Plasma insulin was greater (P ≤ 0.04) in calves from multiparous dams at 12, 48, and 72 h, but parity did not affect (P ≥ 0.18) serum total protein or plasma cortisol. Serum aspartate aminotransferase was greater (P ≤ 0.04) at 6 and 24 h, creatine kinase was greater at 24 h, and gamma-glutamyl transpeptidase was less (P ≤ 0.04) at 6, 12, and 24 h, for calves from primiparous dams. Calves born to primiparous dams had greater (P ≤ 0.02) total bilirubin and direct bilirubin at 12 and 24 h. Data indicate that calves born to first-parity heifers had decreased perinatal nutrient availability, resulting in reduced fetal and placental growth, as well as greater energy reserve mobilization and metabolic indicators of stress as neonates.

Intrinsic challenges of neonatal adaptation in swine

Abstract. The losses of piglets in commercial pig farming remain at concerning levels and need to be addressed through the implementation of new sustainable breeding and management strategies. In fact, piglets are especially at risk in the first days of life. Both genetics and the farrowing process have been shown to impact piglet vitality. In addition, knowledge of the animal-intrinsic responses in adapting to extra-uterine life is particularly important but is scarcely described in the scientific literature. In this review, the three phases that constitute neonatal adaptation in the pig are systematically presented. The first phase of early adaptation involves primarily the development of cardiorespiratory function (within the first 10 min of life) as well as thermoregulatory processes and acid–base balance (up to 24 h of life). In the second phase, homeostasis is established, and organ maturation takes place (up to 14 d post natum). The final third phase aims at the development of neurological, immunological and muscular features (up to 28 d of life). The involvement of aggravating and ameliorating factors such as dystocia, low colostrum yield and heat supply is key to the development of strategies to reduce piglet losses and increase vitality. The insights are of particular value in addressing current concerns in pig farming and to further improve animal welfare in pig production across different management types.

Analgesia during Parturition in Domestic Animals: Perspectives and Controversies on Its Use

This article analyzes the physiological role of pain during parturition in domestic animals, discusses the controversies surrounding the use of opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local analgesics as treatments during labor, and presents the advantages and disadvantages for mother and offspring. Labor is a potentially stressful and painful event, due to the contractions that promote expulsion of the fetus. During labor, neurotransmitters such as the prostaglandins contribute to the sensitization of oxytocin receptors in the myometrium and the activation of nociceptive fibers, thus supporting the physiological role of pain. Endogenously, the body secretes opioid peptides that modulate harmful stimuli and, at the same time, can inhibit oxytocin's action in the myometrium. Treating pain during the different stages of parturition is an option that can help prevent such consequences as tachycardia, changes in breathing patterns, and respiratory acidosis, all of which can harm the wellbeing of offspring. However, studies have found that some analgesics can promote myometrial contractility, increase expulsion time, affect fetal circulation, and alter mother-offspring recognition due to hypnotic effects. Other data, however, indicate that reducing the number of uterine contractions with analgesics increases their potency, thus improving maternal performance. Managing pain during labor requires understanding the tocolytic properties of analgesics and their advantages in preventing the consequences of pain.

Welfare of cattle during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of the animal welfare legislation. The present Opinion deals with protection of cattle (including calves) during transport. Welfare of cattle during transport by road is the main focus, but other means of transport are also covered. Current practices related to transport of cattle during the different stages (preparation, loading/unloading, transit and journey breaks) are described. Overall, 11 welfare consequences were identified as being highly relevant for the welfare of cattle during transport based on severity, duration and frequency of occurrence: group stress, handling stress, heat stress, injuries, motion stress, prolonged hunger, prolonged thirst, respiratory disorders, restriction of movement, resting problems and sensory overstimulation. These welfare consequences and their animal-based measures are described. A variety of hazards, mainly relating to inexperienced/untrained handlers, inappropriate handling, structural deficiencies of vehicles and facilities, poor driving conditions, unfavourable microclimatic and environmental conditions, and poor husbandry practices leading to these welfare consequences were identified. The Opinion contains general and specific conclusions relating to the different stages of transport for cattle. Recommendations to prevent hazards and to correct or mitigate welfare consequences have been developed. Recommendations were also developed to define quantitative thresholds for microclimatic conditions within the means of transport and spatial thresholds (minimum space allowance). The development of welfare consequences over time was assessed in relation to maximum journey duration. The Opinion covers specific animal transport scenarios identified by the European Commission relating to transport of unweaned calves, cull cows, the export of cattle by livestock vessels, the export of cattle by road, roll-on-roll-off ferries and 'special health status animals', and lists welfare concerns associated with these.

Factors influencing ease of whelping and its relationship with maternal behaviour and puppy perinatal mortality in commercially bred dogs

For dog breeders, parturition is a critical stage in the reproductive cycle of the dam. Evidence in other mammals suggests that a difficult labour can influence maternal behaviour and offspring viability during the first hours postpartum. However, the effect of whelping difficulty on the onset of maternal behaviour has not yet been investigated in domestic dogs. Here we developed an ease of whelping (EoW) index in dams maintained within a Commercial dog Breeding Establishment (CBE) environment and investigated the relationship between intrinsic and extrinsic factors (breed group according to size/weight, litter size, parity, whelping season and origin of the dam), EoW, early maternal behaviour and puppy perinatal mortality. The behaviour of 30 dams was observed throughout the whelping process, starting 24 h before delivery of the first puppy until birth of the last puppy. Parturition duration, birth interval, and behaviours indicative of distress, restlessness, and general activity were scored and included in a Principal Component Analysis to construct the EoW index. Subsequently, mother-pup interactions and puppy perinatal mortality were recorded during the first 24 and 72 h postpartum respectively. Results showed that EoW was significantly affected by whelping season, litter size and origin of the dam (whether she was born and raised within the CBE or brought in). Furthermore, mothers that experienced more difficult parturitions (higher EoW score) spent more time lying in contact with their puppies during the first 24 h postpartum. Time in contact with puppies was also significantly affected by breed group. Nursing duration was significantly affected by breed group and origin of the dam. Additionally, medium-size breed (10-20 kg) puppies were significantly less likely to experience perinatal mortality than large breeds (> 20 kg). These findings are particularly relevant for the welfare of breeding dams maintained in large-scale CBEs where the staff-to-dog ratio might be insufficient to adequately manage multiple simultaneous parturitions.

Birth, love, and fear: Physiological networks from pregnancy to parenthood

Pregnancy and childbirth are among the most dramatic physiological and emotional transformations of a lifetime. Despite their central importance to human survival, many gaps remain in our understanding of the temporal progression of and mechanisms underlying the transition to new parenthood. The goal of this paper is to outline the physiological and emotional development of the maternal-infant dyad from late pregnancy to the postpartum period, and to provide a framework to investigate this development using non-invasive timeseries. We focus on the interaction among neuroendocrine, emotional, and autonomic outputs in the context of late pregnancy, parturition, and post-partum. We then propose that coupled dynamics in these outputs can be leveraged to map both physiologic and pathologic pregnancy, parturition, and parenthood. This approach could address gaps in our knowledge and enable early detection or prediction of problems, with both personalized depth and broad population scale.

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Giving birth and caring for offspring are dynamic processes that can instill both love and fear.

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Maternal physiology continuously integrates fetal, social, and environmental cues.

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The result is coupled change in hormonal, autonomic nervous, and emotional output.

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Coupling may allow internal state to be assessed from peripheral autonomic markers.

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Such markers may identify healthy or pathologic pregnancy, parturition, and parenting, and enable creation of real-world tools.

Parturition in Mammals: Animal Models, Pain and Distress

Parturition is a complex physiological process and involves many hormonal, morphological, physiological, and behavioural changes. Labour is a crucial moment for numerous species and is usually the most painful experience in females. Contrary to the extensive research in humans, there are limited pain studies associated with the birth process in domestic animals. Nonetheless, awareness of parturition has increased among the public, owners, and the scientific community during recent years. Dystocia is a significant factor that increases the level of parturition pain. It is considered less common in polytocous species because newborns' number and small size might lead to the belief that the parturition process is less painful than in monotocous animal species and humans. This review aims to provide elements of the current knowledge about human labour pain (monotocous species), the relevant contribution of the rat model to human labour pain, and the current clinical and experimental knowledge of parturition pain mechanisms in domestic animals that support the fact that domestic polytocous species also experience pain. Moreover, both for women and domestic animal species, parturition's pain represents a potential welfare concern, and information on pain indicators and the appropriate analgesic therapy are discussed.

Synthetic Olfactory Agonist Use in the Farrowing House to Reduce Sow Distress and Improve Piglet Survival

The aim of the study was to investigate if the application of a synthetic olfactory agonist (SOA) would reduce indicators of stress in sows, in response to a stressor prior to parturition, and if it would improve farrowing house performance of sows and their piglets. Two studies were conducted: an intensive study with 47 sows, either having their first or second litter (Control n = 24; SOA n = 23); and a commercial validation study with 418 sows, either having their first litter or have had multiple litters (Control n = 210; SOA n = 208). Within the intensive study, sows were housed with or without a synthetic olfactory agonist suspended in the creep area of the farrowing crate, whereas within the commercial validation study, sows were housed with or without a synthetic olfactory agonist suspended over the adjoining creep area of two farrowing crates. Within the intensive study, despite a discernible increase in cortisol concentration in response to a stressor (snout rope test), cortisol response was not different between treatments (p > 0.05). Farrowing duration in first-litter sows exposed to the SOA was decreased (p < 0.001) whilst there was no impact on farrowing duration in second litter sows. Piglets were not attracted by the SOA to increase their utilisation of the creep area and spent more time in proximity to the sow (p < 0.05). Within the commercial validation study, no impacts were seen on piglet production measures (p > 0.05). Largely the use of an SOA within the farrowing house did not impact the sow or her piglets in either the intensive study or commercial validation study. Based on these current results, the use of SOA within the farrowing house is not supported.

Circulating oxidative stress status in Bedouin she-camels (Camelus dromedarius) during the peripartum period

This study aimed to assess the oxidative stress status in blood plasma of nomadic she-camels (Camelus dromedarius) during transition from late pregnancy to early lactation. From 12 late pregnant she-camels, blood was sampled weekly as they progressed from the third week prepartum up to the third week postpartum. Levels of albumin, uric acid, and malondialdehyde (a biomarker of lipid peroxidation) concentrations were fairly constant (P > 0.05) throughout the sampling times. Compared to the initial time (third week prepartum), values of the superoxide anion, total peroxides, and protein carbonyl (a biomarker of protein peroxidation) increased (P < 0.05) by more than 67%, 43%, and 23%, respectively, at parturition and this increase extended to the first week postpartum. Ascorbic acid concentration lost more than 20% (P < 0.05) of its value at parturition. Bilirubin value increased as camels progressed from the first week pre- up to the first week postpartum, and reached its maximum value (~ 2.5 fold) at parturition. Superoxide dismutase activity increased (P < 0.05) by 71.7% at the first week pretpartum and by 57% at parturition. Total antioxidant capacity level increased (P < 0.05) by ~ 25% at the first week prepartum and remained at this high level up to the second week postpartum. It seems that periparturient camels experience a substantial oxidative stress particularly at parturition and the week after calving as indicated by the increased peroxidative by-products of proteins in parallel to the enhanced production of pro-oxidants.

Low CLOCK and CRY2 in 2nd trimester human maternal blood and risk of preterm birth: A nested case-control study

Previous studies have observed an association between maternal circadian rhythm disruption and preterm birth (PTB). However, the underlying molecular mechanisms and the potential of circadian clock genes to serve as predictors of PTB remain unexplored. We examined the association of 10 core circadian transcripts in maternal blood with spontaneous PTB (sPTB) vs term births using a nested case-control study design. We used a public gene expression dataset (GSE59491), which was nested within the All Our Babies (AOB) study cohort in Canada. Maternal blood was sampled in trimesters 2-3 from women with sPTB (n = 51) and term births (n = 106), matched for 5 demographic variables. In 2nd trimester maternal blood, only CLOCK and CRY2 transcripts were significantly lower in sPTB vs term (p = 0.02 ~ 0.03, FDR < 0.20). A change of PER3 mRNA from trimesters 2 to 3 was significantly associated with sPTB (decline in sPTB, p = 0.02, FDR < 0.20). When CLOCK and CRY2 were modeled together in 2nd trimester blood, the odds ratio of being in the low level of both circadian gene transcripts was greater in sPTB vs term (OR = 4.86, 95%CI = (1.75,13.51), p < 0.01). Using GSVA and Pearson correlation, we identified 98 common pathways that were negatively or positively correlated with CLOCK and CRY2 expression (all p < 0.05, FDR < 0.10). The top three identified pathways were amyotrophic lateral sclerosis, degradation of extracellular matrix, and inwardly rectifying potassium channels. These three processes have previously been shown to be involved in neuron death, parturition, and uterine excitability during pregnancy, respectively.

Assessments of Heart Rate and Sympathetic and Parasympathetic Nervous Activities of Normal Mouse Fetuses at Different Stages of Fetal Development Using Fetal Electrocardiography

Heart rate is controlled by the activity of the autonomic nervous system: the sympathetic and parasympathetic nervous systems increase and suppress heart rate, respectively. To evaluate the activity of the autonomic nervous system, it is possible to determine heart rate variability using electrocardiography (ECG). During the fetal period, the heart and autonomic nerves develop in coordination; however, physiological changes, including autonomic nervous activities that occur during the fetal stage, remain largely unknown. Therefore, in this study, we measured ECG signals of mouse fetuses using our established method to evaluate the development of heart rate and autonomic nervous activity at different fetal developmental stages. We found that heart rate was significantly increased in fetal mice at embryonic day (E) 18.5 compared with that at E13.5, E15.5, and E17.5, indicating that fetal heart rate increases only at the stage immediately prior to birth. Interestingly, fetal parasympathetic nervous activity was reduced at E17.5 and E18.5 compared with that at E13.5, whereas fetal sympathetic nervous activity remained unchanged, at least from E13.5 to E18.5. These results indicate that parasympathetic activity rather than sympathetic activity affects fetal heart rate and that the decrease in parasympathetic activity toward the end of pregnancy could result in the observed increase in fetal heart rate.

The effect of stocking density and a blind on the behavior of Holstein dairy cows in group maternity pens. Part II: Labor length, lying behavior, and social behavior

In natural settings, dairy cows separate from the herd to give birth. When kept indoors, seeking isolation before calving may be restricted and may depend on space and resources provided in maternity housing. The effect of group maternity pens on behavior around calving and labor progress is unknown. Therefore, the objective of this study was to determine the effects of stocking density and provision of a blind in group bedded pack maternity pens on lying and social behavior as well as length of labor of preparturient dairy animals. The study was conducted as a complete randomized block design with a 2 × 2 factorial arrangement of treatments including stocking density and presence or absence of a blind, resulting in a total of 4 treatments: (1) high stocking density (7.7-12.9 m² lying space/cow) with a blind, (2) low stocking density (15.4-25.8 m²) with a blind, (3) high stocking density without a blind, and (4) low stocking density without a blind. A total of 127 primiparous heifers and 247 multiparous cows were housed in mixed-parity groups from approximately 3 wk before and immediately after calving. During the 4 h before calving, lying behavior (lying time and bouts) was collected automatically using accelerometers, and social behavior (agonistic interactions, allogrooming, and attention from other cows), stage II labor duration, and frequency of position change during stage II labor were collected using video. Lying behavior was collected with accelerometers. Regardless of treatment, lying time and bouts increased as calving approached. Cows and heifers performed more lying bouts in low stocking density pens compared with high stocking density pens. Agonistic interactions and allogrooming were not different between treatments. Other cows spent more time paying attention to focal animals regardless of stocking density as calving approached, but time spent paying attention was reduced by the presence of a blind during h -2 before calving. The hazard of calving unassisted was greater for cows and heifers in low stocking density pens with a blind compared with all other treatments. Further, animals in pens with a blind tended to change positions fewer times during stage II labor. These results suggest that providing a blind in group maternity pens may improve the calving environment for cows and heifers and, in combination with low stocking density, may reduce the amount of time spent in labor.

Stress reactivity near birth affects nest building timing and offspring number and survival in the European rabbit (Oryctolagus cuniculus)

The physiological response to stressors has great importance, and its variance has an adaptive role in the survival of individuals. This study describes the effects of stress-axis activation on maternal behavior during the birthing process (parturition) in captive rabbits (Oryctolagus cuniculus). In this species, chances of survival are strongly influenced by nest quality. Thus, maternal care is initiated with nest preparation in late pregnancy, which itself is subject to strict and complex hormonal regulation. Among these hormones, progesterone is one of the most dominant in the process of nest construction. We have demonstrated that its level is altered by the level of cortisol elevation in the animal in question, potentially having an influence on the preparation of the nest for the newborn kittens. We found that does that had a constant and un-elevated level of cortisol metabolite while delivering their litters performed better than those individuals that showed an increased corticoid response around parturition. The latter group exhibited a perceptible delay in the building of their nests, and in addition, further losses were also experienced in their already smaller litters. As the quality of the nest itself proved to be was in no way inferior to those of the other group, this higher kitten-mortality rate may be attributed to impaired maternal behavior. Individual variances in cortisol levels may also result in subtle changes in hormonal regulation, potentially affecting the expression of maternal behavior. We have concluded that the higher level of cortisol detected in more-sensitive does effectively disrupts the natural hormonal regulation involved in their nest-building processes.

The Role of Oxytocin and the Effect of Stress During Childbirth: Neurobiological Basics and Implications for Mother and Child

The neuropeptide oxytocin acts as a hormone and a neuromodulator, influencing a multitude of human social behaviors, including reproduction. During childbirth and the postpartum period, it plays a key role in regulating and controlling processes that ensure a safe birth and the health of mother and child. Especially the onset of labor, the progress of labor and initial breastfeeding are mediated by oxytocin. In the maternal brain it controls the initiation of the mother-infant bond and the mother's emotional responses towards her child. In this review we summarize the current state of knowledge about the role of oxytocin during the different aspects and mechanisms of human childbirth, combining research from human and animal studies. Physiological and psychological stress during childbirth and lactation can have negative effects on the progress of labor, breastfeeding and bonding. We discuss how maternity caregivers can support the positive effects of oxytocin and minimize the effects of stress. Furthermore, we highlight aspects of the basic neurobiological principles and connections where further research is needed to improve our understanding of the regulation and the effects of oxytocin to support maternal and infant health.

Effects of uterotonics on farrowing traits and piglet vitality: A systematic review and meta-analysis

Uterotonics are widely used in the pig industry but their effects have not been investigated critically. The objective was to evaluate the effects of oxytocin and carbetocin on farrowing duration, birth interval, farrowing assistance, stillbirth rate, and piglet viability traits by performing a systematic review and a meta-analysis. The search for studies was performed during January 2020 using the PubMed, ISI Web of Science, Science Direct, and Scopus databases. The literature search was conducted using the key words: oxytocin, pig, farrowing, stillbirth, piglet, dose, and carbetocin. Studies which evaluated the effects of oxytocin or carbetocin on farrowing duration, birth interval, stillbirth rate, and farrowing assistance were included in the review. Of 1215 articles, 23 (1.9%) were selected for fulfilling the criteria for inclusion in the present study. A high variety of doses was observed among studies. Oxytocin increased (30%; P < 0.05) the stillborn proportion in the litters compared to control sows. Both oxytocin and carbetocin increased the need of farrowing assistance by 137% (P < 0.01) and 40% (P < 0.05), respectively, compared to control. The use of oxytocin reduced the farrowing duration by 18% and the birth interval by 17%, while carbetocin reduced the same responses by 27 and 23%, respectively (P < 0.01). When used judiciously, uterotonics are a valuable tool to shorten farrowing duration of hyperprolific sows. However, the treatment is not exempt of deleterious effects for piglets and sows. Therefore, the criteria to use these drugs should be based on individual cases and not as part of hormonal protocols for all parturient sows.

Porcine soluble CD83 alleviates LPS-induced abortion in mice by promoting Th2 cytokine production, Treg cell generation and trophoblast invasion

CD83, either in its membrance-bound form (mCD83) or soluble form (sCD83), is an important immunomodulatory molecule in humans and mice. While mCD83 is immunostimulatory, sCD83 exhibits striking immunosuppressive activities, suggesting that sCD83 may be used to combat inflammatory diseases, such as rheumatoid arthritis, graft-versus-host disease and habitual abortion. Although many studies had shed lights on the role of CD83 in humans and mice, little is known about CD83 in other animals. Recently, we showed that porcine CD83 had similar biochemical characteristics and immunoregulatory functions as its human counterpart. However, whether porcine sCD83 (psCD83) is involved in maintaining the immunological tolerance at the maternal-fetal interface and thereby prevents embryo loss and abortion during pregnancy is unclear. In this study, we used LPS-induced animal model to analyze the effect of porcine sCD83 on the mouse abortion. Results showed that psCD83 could significantly alleviate LPS-induced abortion in mice, indicating that the psCD83 had the function of fetal protection. Mechanically, psCD83-mediated fetal protection was related to the promotion on Th2 cytokine production, Treg cell differentiation and trophoblast invasion. This study provides a molecular basis for the fetal protection of psCD83, as well as a potential target for the regulation of maternal-fetal interfacial immune tolerance.

Zoo-housed mammals do not avoid giving birth on weekends

There is evidence that zoo visitor presence can influence the behaviour and, in some cases, adrenal response of zoo animals, and can sometimes compromise animal welfare. In some laboratory studies, significantly more primate births have been reported on weekends, when fewer people are working there, compared with weekdays when staffing levels are at their highest. Here, we investigate whether there is evidence of a "weekend effect" on births in zoo animals as a result of visitor numbers. Unlike laboratories, zoos are typically busier with visitors on weekends than on weekdays, although staffing levels remain fairly consistent across days of the week. If zoo animal parturition is sensitive to human presence, then fewer births would be expected on weekends compared with weekdays. We tested this using birth data and visitor numbers on the entrance gate from zoo records across 16 species representing artiodactyls, perissodactyls, carnivores and primates at four British zoos, to see whether there is an association between mean daily birth rates and average visitor numbers. We predict that, if there is a visitor effect, daily births should be lower on weekends than weekdays and should correlate with mean daily visitor numbers. Results showed that births for all 16 species were randomly distributed through the week, and there was no significant decline in births on weekends. We conclude that the "weekend effect", if such a thing exists, does not appear to be a feature of zoo births, suggesting that elevated weekend visitor numbers are not sufficiently stressful to trigger delayed parturition.

Differences in Endocrine and Cardiac Changes in Mares and Her Fetus before, during, and after Parturition in Horses of Different Size

Simple Summary

Monitoring of the pregnant mare and her fetus is based on hormone analysis and heart rate recordings 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 before and at foaling. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares. The concentrations of progestins (hormones that maintain pregnancy) and cortisol (a hormone involved in the onset of foaling but also in an animal’s response to stress) was highest in full-size mares. Progestin concentration decreased towards foaling while cortisol concentration increased. Heart rate of mares increased before foaling with the most pronounced increase in small mares. Overall, Shetland mares foaled earlier than larger-size mares. At foaling, atrio-ventricular blocks (physiological omission of heart beats) regularly occurred in full-size mares but only occasionally in medium-size and small mares, reflecting differences in heart efficiency. In conclusion, some differences exist before and at foaling in horses of different size.

Abstract

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.

Exploring the Genetic Background of the Differences in Nest-Building Behavior in European Rabbit

Once a day, nursing and absentee mothering make the wild rabbit (Oryctolagus cuniculus) an ideal model animal for measuring differences in maternal behavior. Behavioral events and their hormonal regulation leading to parturition are well documented; however, the genetic background behind individual differences in this complex process is unknown. Decreased progesterone hormone level and the reduction of progesterone receptor activity are crucial to initiating the collection of nest material. The progesterone receptor gene is a likely candidate affecting nest-building behavior. In addition to several known point mutations in the progesterone receptor gene of the European wild rabbit, we have found a new mutation in the promoter region of the gene at 2682 T > C. Although this new single nucleotide polymorphism (SNP) was not involved in the formation of the nest-building behavior, an SNP (2464G > A) already described in the promoter region showed an association with individual differences in the initiation of hay carrying. The distribution of this SNP delivered an opposite result compared to domestic rabbits. Genotype (GG) with high uterine capacity was most frequent; the hereditary value of the trait was h² = 0.10. Thus, progesterone receptor gene polymorphism may manifest in individual differences affecting breeding success in this species.

Prenatal Maternal Stress Causes Preterm Birth and Affects Neonatal Adaptive Immunity in Mice

Maternal stress is a well-established risk factor for preterm birth and has been associated with adverse neonatal outcomes in the first and subsequent generations, including increased susceptibility to disease and lasting immunological changes. However, a causal link between prenatal maternal stress and preterm birth, as well as compromised neonatal immunity, has yet to be established. To fill this gap in knowledge, we used a murine model of prenatal maternal stress across three generations and high-dimensional flow cytometry to evaluate neonatal adaptive immunity. We report that recurrent prenatal maternal stress induced preterm birth in the first and second filial generations and negatively impacted early neonatal growth. Strikingly, prenatal maternal stress induced a systematic reduction in T cells and B cells, the former including regulatory CD4+ T cells as well as IL-4- and IL-17A-producing T cells, in the second generation. Yet, neonatal adaptive immunity gained resilience against prenatal maternal stress by the third generation. We also show that the rate of prenatal maternal stress-induced preterm birth can be reduced upon cessation of stress, though neonatal growth impairments persisted. These findings provide evidence that prenatal maternal stress causes preterm birth and affects neonatal immunity across generations, adverse effects that can be ameliorated upon cessation.

Road Transport of Late-Pregnant Mares Advances the Onset of Foaling

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.

Controlled delay of the expulsive phase of foaling affects sympathoadrenal activity and acid base balance of foals in the immediate postnatal phase

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 5 min by transferring mares to an unfamiliar environment at rupture of the allantochorion (group delay, n = 6) while control mares (n = 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 30 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 15 min postnatum (p < 0.001) while HRV decreased during the first hour of life in foals of both groups (p < 0.05). Immediately after birth, actual base excess was lower in foals with delayed birth than in control foals (p < 0.05). Epinephrine concentration immediately after birth was higher in group delay foals and increased from 0 to 30 min after birth in control foals (time p < 0.001, time x group p = 0.001). Cortisol concentration peaked at 1 h after birth in both groups (p < 0.001). Leukocyte and PMN count decreased from 0 to 30 min after birth (p < 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.