Vaginal Temperature Research Articles

Comparation of Physiology, Diameter of Ovary and Follicle at PO Cows Treated Different Method of Estrus Synchronization

One of the biotechnology reproductive used is estrus synchronization. This study determined the body’s physiological, estradiol level, and ovarian and follicle diameter in Peranakan Ongole (PO) cow estrus synchronization using modified progesterone-PGF2α and double injection of PGF2α. This study used 10 PO cows which were divided into two groups. Group 1, cows were given a modified intravaginal sponge containing 250 mg progesterone/sponge for 6 days, followed by intramuscularly injection of PGF2ɑ 25 mg/cow on day sixth. Appearance of estrus was observed on day 7th -9th. Group 2, cows were given a double injection 25 mg/cow of PGF2ɑ intramuscularly at 14-day intervals, then estrus was observed on day 15th -17th. The vaginal temperature was checked using a thermometer, the respiratory frequency was checked by inspection of thorax movements, and the pulse rate was checked by palpation of the coccygeal artery. Ovarian and Graafian follicle diameters were examined using ultrasonography. The data were analyzed using either T-Test or descriptive test. The results showed that in cows that were synchronized to estrus using combination of modified progesterone-PGF2ɑ and double injection of PGF2ɑ, the vaginal temperature, pulse rate, and respiration frequency were 36.9±0.98 and 37.34±0.83, 57.60±12.52 and 74.80±26.59, 30.40±10.43 and 20.00±2.83 respectively. There was no significant difference in ovarian and follicle diameter (P>0.05). The conclusion was the results of body physiology were in normal conditions but still below the average of cows undergoing estrus, and there were no significant differences in ovarian and Graafian follicle diameters.

Measuring the effects of estrus on rumen temperature and environment, behavior and physiological attributes in Korean Native breeding cattle.

In this study, rumen temperature and environment in estral and non-estral Korean Native breeding cattle were evaluated by using a bolus sensor. Behavioral and physiological changes in study animals were also assessed. To assess the rumen temperature and environment, we inserted bolus sensors into 12 Korean Native cattle with an average age of 35.5 months, then measured temperature and activity within the rumen using the wireless bolus sensor. Drinking, feeding and mounting behavior, and measured vaginal temperature and levels of intravaginal mucus resistance were recorded. We found that cattle in estrus exhibited more acts of mounting (37.4 vs. 0 times/day), increased vaginal temperature (39.0°C vs. 38.4°C), and decreased vaginal mucus resistance (136.3 Ω vs 197.4 Ω), compared with non-estral animals. Furthermore, increased levels of rumen activity were most significant in estrus cattle at the highest activity levels (p < 0.01). Overall, the estrus group exhibited increased rumen temperature (p = 0.01), compared with the non-estrus group. In conclusion, the results of this study not only provide basic physiological data related to estrus in improved Korean Native breeding cattle, but also suggest that monitoring of rumen temperature and activity might be used as an effective smart device for estrus detection.

Differences in body temperature regulation during heat stress and seasonal depression in milk yield between Holstein, Brown Swiss, and crossbred cows

It is not clear whether cattle that are genetically superior in regulation of body temperature during heat stress are also better able to sustain milk production during hot conditions. Objectives were to evaluate differences in body temperature regulation during heat stress between Holstein, Brown Swiss, and crossbred cows under semi-tropical conditions and test whether the seasonal depression in milk yield was greater for genetic groups less able to regulate body temperature. For the first objective, conducted during heat stress, vaginal temperature was measured at 15-min intervals for 5 d in 133 pregnant lactating cows. Vaginal temperatures were affected by time and interaction between genetic group and time. Vaginal temperatures were higher for Holsteins for most times of the day. Moreover, the maximum daily vaginal temperature was higher for Holstein (39.8 ± 0.1°C) than for Brown Swiss (39.3 ± 0.2°C) or crossbreds (39.2 ± 0.1°C). For the second objective, 6,179 lactation records from 2,976 cows were analyzed to determine effects of genetic group and season of calving (cool season = Oct to March; warm season = April to Sept) on 305-d milk yield. Milk yield was affected by genetic group and season but not by the interaction of genetic group and season. The difference in average 305-d milk yield between cows calving in cool versus hot weather was 310 kg (4% decrease) for Holstein, 480 kg (7% decrease) for Brown Swiss, and 420 kg (6% decrease) for crossbreds. In conclusion, Brown Swiss and crossbreds regulated body temperature during heat stress better than Holsteins but these breeds were not more resistant to heat stress with respect to milk yield. Thus, genetic differences in thermotolerance are likely to exist that are independent of regulation of body temperature.

An automated system for cattle reproductive management under the IoT framework. Part I: the e-Synch system and cow responses

The objective of this manuscript was to present the e-Synch system, integrating an intravaginal electronically controlled hormone delivery and sensing device with an IoT platform for remote programming and monitoring. Secondary objectives were to demonstrate system functionality and cow responses to e-Synch. External components of e-Synch include a 3D-printed case with retention wings, a flexible wideband antenna, and silicone membrane for pressure balancing. Internal components include a central control board, battery, wireless charging coil, and two silicone hormone reservoirs connected to individual peristaltic pumps. An accelerometer and a high-accuracy temperature sensor are integrated in the custom printed circuit board (PCB). The IoT platform includes a gateway consisting of Raspberry PI 3 and a CC1352 radiofrequency module that collects sensor data at 915 mHz. Data is transferred to the Google Cloud utilizing the IoT Core service through TCP/IP, and then is pulled by the Pub/Sub service. After routing to a BigQuery table by the Dataflow service, data visualization is provided by Data Studio. Drug delivery protocols are selected using an IOS device app that connects to e-Synch through Bluetooth. Experiments with lactating Holsteins cows were conducted to demonstrate proof-of-concept system functionality and evaluate cow responses. Despite unstable communication and signal discontinuity because of signal strength attenuation by body tissue, devices (n=6) communicated with the IoT platform in 89% (24/27) of use instances. Temperature and accelerometer data were received for at least one 15 min period during an 8 h insertion period from all devices that communicated with the IoT platform. Variation in accelerometer data (± 8.565 m/s2) was consistent with cow activity during experimentation and mean vaginal temperature of 39.1 °C (range 38.6 to 39.5 °C) demonstrated sensor functionality. Hormone release was confirmed in all instances of device use except for one. Cow behavior evaluated through signs of discomfort and pain, and tail raising scores was mostly unaltered by e-Synch. Vaginal integrity and mucus scores also remained unaltered during and after device insertion. In conclusion, the e-Synch device integrated with a controlling app and IoT platform might be used to automate intravaginal hormone delivery and sensing for controlling the estrous cycle of cattle.

Predicting physiological responses of dairy cows using comprehensive variables

Heat stress is increasingly affecting the production, health, and reproduction of dairy cows. Previous studies used limited variables as predictors of physiological responses, and the developed models poorly predict animal responses in evaporatively cooled environments. The aim of this study was to build machine learning models using comprehensive variables to predict physiological responses of dairy cows raised on an actual dairy farm equipped with sprinklers. Four algorithms including random forests, gradient boosting machines, artificial neural networks (ANN), and regularized linear regression were used to predict respiration rate (RR), vaginal temperature (VT), and eye temperature (ET) with 13 predictor variables from three dimensions: production, cow-related, and environmental factors. The classification performance of the predicted values in recognizing individual heat stress states was compared with commonly used thermal indices. The performance on the testing sets shows that the ANN models yielded the lowest root mean squared error for predicting RR (13.24 breaths/min), VT (0.30 °C), and ET (0.29 °C). The results interpreted with partial dependence plots and Local Interpretable Model-agnostic Explanations show that P.M. measurements and winter calving contributed most to high RR and VT predictions, whereas lying posture, high ambient temperature, and low wind speed contributed most to high ET predictions. When determining the ground-truth heat stress state by the actual RR, the best classification performance was yielded by the predicted RR with an accuracy of 77.7%; when determining the ground-truth heat stress state by the actual VT, the best classification performance was yielded by the predicted VT with an accuracy of 75.3%. This study demonstrates the ability of ANN in predicting physiological responses of dairy cows raised on actual farms with access to sprinklers. Adding more predictors other than meteorological parameters into training could increase predictive performance. Recognizing the heat stress state of individual animals, especially those at the highest risk, based on the predicted physiological responses and their interpretations can inform better heat abatement decisions.

Short-term physiological responses to moderate heat stress in grazing dairy cows in temperate climate.

Even in temperate climate regions, an increase in ambient temperature and exposure to solar radiation can cause heat stress in lactating dairy cows. We hypothesised that grazing dairy cows exhibit short-term physiological changes due to increasing heat load under moderate climate conditions. Over two consecutive summers, 38 lactating Holstein dairy cows were studied in a full-time grazing system. Data were collected in 10 experimental periods of up to three consecutive days with a moderate comprehensive climate index (CCI). The individual animals' vaginal temperature (VT), heart rate, and locomotor activity data were automatically monitored with sensors. Blood samples and proportional whole milk samples were collected at afternoon milking. The concentrations of beta-hydroxybutyrate, glucose, non-esterified fatty acids, urea nitrogen, plasma thyroxine and triiodothyronine were analysed in blood plasma, and fat, protein, lactose, urea nitrogen, cortisol, Na+, K+, and Cl- concentrations were analysed in milk. The daily distribution of VT recordings greater than 39°C showed a circadian rhythm with a proportion of recordings of 2% and lower during the night and a percentage of 10% or higher in the afternoon. The cows' maximal daily vaginal temperature (VTMAX) between 0830 and 1430h was positively related to the mean daily CCI in the same time period (CCIMEAN; mean and SD 23.6±5.4°C). Cows with greater VTMAX had an increased mean heart rate, plasma glucose and milk cortisol concentrations and decreased concentrations of plasma thyroxine and triiodothyronine. The concentration of Na+ in milk was lower, and the concentration of K+ in milk tended to be higher in cows with increased VTMAX. For beta-hydroxybutyrate, non-esterified fatty acids and urea nitrogen concentrations in plasma and fat and lactose concentrations in milk no relationships were found in terms of increasing VT. For milk urea nitrogen and protein concentrations, the proportion of total variance explained by inter-individual or -period variance was high. In conclusion, changes observed in milk and blood likely reflected short-term physiological responses to moderate heat stress. In particular, milk cortisol and Na+ may be useful traits for timely monitoring of heat stress in individual cows because their inter-individual variances were relatively small and samples can be collected non-invasively.

Use of Solar Panels for Shade for Holstein Heifers.

Animal Agrivoltaics combines electric energy generation, animal thermal comfort, and sustainable production at the same time. This model of production can foster the sustainable intensification of dairy production in tropical areas where solar irradiance is high and nearly constant throughout the year. In this study, we propose Animal Agrivoltaics as an alternative practice to reduce the heat load and eCH4 emissions from dairy heifers in tropical areas. To attest this hypothesis, (1) the meteorological data and the behavioral and physiological responses of the animals were integrated in order to determine the benefits provided by the shade from the solar panels on the thermoregulation of the dairy heifers, and (2) measurements of the enteric methane emissions were taken to determine the potential of the solar panels to offset the GHG. Seven crossbred Holstein heifers (7/8, Holstein × Gyr) with a mean body weight of 242 kg (SD = 53.5) were evaluated in a paddock shaded with ten modules of solar panels. Miniature temperature loggers were used to record the body surface, skin and vaginal temperatures of the heifers every five minutes. The respiratory rate and the shade-use behavior were also monitored by two observers. These measurements were taken from 08:00 to 17:00 h for 18 consecutive days. After completing the field study, the heifers underwent for assessments of the daily oscillations of eCH4 emission using a flow-through respirometry system. The use of shade by the heifers was progressively increased (p < 0.01) with an increasing level of solar irradiance. Lying and ruminating were more likely (p < 0.01) to occur when the heifers were in the shade, especially when the solar irradiance exceeded 500 W m-2. Between 10:00 and 14:00 h, the heifers benefited from the shade produced by the solar panels, with a reduction of 40% in the radiant heat load. With an increasing intensity of solar irradiance, body surface temperature, skin temperature and respiratory rate of the heifers in the shade were lower (p < 0.01) compared to when they were exposed to the sun. The heifers had a daily methane emission total of 63.5 g per animal-1 or 1.7 kg of CO2-eq. Based on this emission rate and the amount of CO2-eq that was not emitted to the atmosphere due to the electricity generated by solar panels, 4.1 m2 of panels per animal (nominal power = 335 W) would be expected to obtain a net-zero eCH4 emission. Over a period of one year (from September 2018 to August 2019), a set of ten photovoltaic panels used in the study produced 4869.4 kWh of electricity, thereby saving US $970.00 or US $48.00 per m2 of solar panel. Based on the results of this study, it can be concluded that use of Animal Agrivoltaics, in addition to producing electricity, has significant potential benefit in providing better thermal comfort to cattle, as well as offsetting the enteric methane emissions released into the environment. In addition, the system would provide extra income to farmers, as well as a potential source of energy micro-generation.

Evaluating phenotypes associated with heat tolerance and identifying moderate and severe heat stress thresholds in lactating sows housed in mechanically or naturally ventilated barns during the summer under commercial conditions.

An accurate understanding of heat stress (HS) temperatures and phenotypes that indicate HS tolerance is necessary to improve swine HS resilience. Therefore, the study objectives were 1) to identify phenotypes indicative of HS tolerance, and 2) to determine moderate and severe HS threshold temperatures in lactating sows. Multiparous (4.10 ± 1.48) lactating sows and their litters (11.10 ± 2.33 piglets/litter) were housed in naturally ventilated (n = 1,015) or mechanically ventilated (n = 630) barns at a commercial sow farm in Maple Hill, NC USA between June 9 and July 24, 2021. In-barn dry bulb temperatures (TDB) and relative humidity were continuously recorded for naturally ventilated (26.38 ± 1.21°C and 83.38 ± 5.40%, respectively) and mechanically ventilated (26.91 ± 1.80°C and 77.13 ± 7.06%, respectively) barns using data recorders. Sows were phenotyped between lactation d 11.28 ± 3.08 and 14.25 ± 3.26. Thermoregulatory measures were obtained daily at 0800, 1200, 1600, and 2000h and included respiration rate, and ear, shoulder, rump, and tail skin temperatures. Vaginal temperatures (TV) were recorded in 10min intervals using data recorders. Anatomical characteristics were recorded, including ear area and length, visual and caliper-assessed body condition scores, and a visually assessed and subjective hair density score. Data were analyzed using PROC MIXED to evaluate the temporal pattern of thermoregulatory responses, phenotype correlations were based on mixed model analyses, and moderate and severe HS inflection points were established by fitting TV as the dependent variable in a cubic function against TDB. Statistical analyses were conducted separately for sows housed in mechanically or naturally ventilated barns because the sow groups were not housed in each facility type simultaneously. The temporal pattern of thermoregulatory responses was similar for naturally and mechanically ventilated barns and several thermoregulatory and anatomical measures were significantly correlated with one another (P < 0.05), including all anatomical measures as well as skin temperatures, respiration rates, and TV. For sows housed in naturally and mechanically ventilated facilities, moderate HS threshold TDB were 27.36 and 26.69°C, respectively, and severe HS threshold TDB were 29.45 and 30.60°C, respectively. In summary, this study provides new information on the variability of HS tolerance phenotypes and environmental conditions that constitute HS in commercially housed lactating sows.

Research of the influence of Melanizol pessaries on background of “chemical” vaginitis in rats

The aim. to study the therapeutic influence of new pessaries Melanizol based on metronidazole and tea tree oil on the background of model of “chemical” vaginitis in female rats.&#x0D; Materials and methods. The therapeutic effect of pessaries Melanizol was studied in female rats on the model of "chemical" vaginitis with using argentum nitrate, which provokes vaginitis not burdened by infection. Against the background of vaginitis, the general condition of animals, the dynamics of body weight, the morphological composition of peripheral blood and the erythrocyte sedimentation rate (ESR), pH, biochemical parameters (total protein, ALT and glucose), temperature in the vagina of rats, macroscopically assessed changes in the vaginal mucosa (VM) were studied.&#x0D; Results and discussion. Against the background of pathology in the animals, a shift in the studied indicators was observed. Pessaries Melanizol at the dose of 21 mg/kg make a therapeutic effect on the model of experimental "chemical" vaginitis, caused by argentum nitrate, as indicated by the restoration of the VM state, reduced the number of leukocytes, restored the percentage composition of the leukocyte formula, reduced the amount of total protein and the cytolytic enzyme ALT in blood serum and vaginal contents, which indicates the anti-inflammatory and cytoprotective effect of the studied agent. The recovery of vaginal temperature, pH and the amount of glucose in the vaginal contents was also observed, which indicates the normalization of homeostasis in the vagina of experimental animals. According to these effects, the studied pessaries Melanizol were superior to the reference drug "Gravagin" at the dose of 30 mg/kg and were not inferior to the reference drug Hippophaes oleum pessaries (HOP) at the dose of 17.64 mg/kg.&#x0D; Conclusions. The therapeutic effect of new pessaries Melanizol based on metronidazole and tea tree oil on the model of "chemical" vaginitis in female rats has been proven. The investigated pessaries Melanizol are a promising drug for the treatment of non-specific vaginitis and require further research in this direction

Bio-loggers inserted in intravaginal sponges, or subcutaneously, as tools to measure body temperature

The body temperature of animals can be measured by thermistors, thermocouples, or radiotelemetry devices that are implanted surgically under the skin, although the suitability of subcutaneous temperature as an indicator of core temperature can be limited because of abnormal temperature readings, probably affected by ambient temperature and animal inactivity. This study compared the use of bio-loggers designed to monitor subcutaneous temperature (Tsub), with their use embedded in intravaginal sponges to measure vaginal temperature (Tvag). Three ewes were implanted with a subcutaneous temperature bio-logger that was configured to record Tsub every 30 min for a month. Ewes were given an intravaginal sponge for 12 days two days later. Inside the sponges were installed programmed bio-loggers that measured Tvag every 5 min. The ambient temperature (Tamb) and relative humidity were monitored using mini data-loggers. Mean Tsub was lower (P < 0.001) during the day (38.02 ± 0.02 °C) than at night (38.10 ± 0.02 °C), with maximum Tsub (38.57 °C) at 20:00 h and minimum temperature (37.36 °C) at 08:00 h; however, mean Tvag was higher (P < 0.001) during the day (38.71 ± 0.01 °C) than at night (38.62 ± 0.01 °C), with maximum Tsub (39.02 °C) at 20:55 h and minimum temperature (38.33 °C) occurred at 08:25 h. Mean Tsub (38.08 ± 0.02 °C) was lower (P < 0.0001) than was Tvag (38.65 ± 0.10 °C) in the daytime and at night (P < 0.001). Both temperatures had a 24-h rhythm (P < 0.0001), but differed (P < 0.001) in the mean midline estimating statistic of rhythm (MESOR) (Tvag: 38.67 ± 0.02 °C, Tsub: 38.09 ± 0.02 °C), amplitude (Tvag: 0.21° ± 0.01C; Tsub: 0.25 ± 0.01 °C), and acrophase (Tvag: 18:27 ± 0.38 h, Tsub: 20:48 ± 0.44 h). The coefficient of correlation between the two temperatures, measured simultaneously for 12 d was 0.644 (P < 0.01), and between Tamb and the two physiological temperatures, measured at the same time throughout the 12 d experiment, was 0.319 (P < 0.01) for Tsub and 0.287 (P < 0.01) for Tvag. The linear regression analysis of the 24 h circadian rhythm in Tsub and Tvag indicated a high coefficient of determination with Tvag (0.9255) and a lower coefficient of determination with Tsub (0.4292). In conclusion, the integration of a mini body temperature logger into a vaginal sponge, or their subcutaneous insertion, provided a continuous and accurate record of body temperature. Furthermore, the strong correlation between mean 24 h circadian Tvag and Tamb, demonstrated the usefulness of Tvag in biometeorological studies in sheep. As an alternative to employing these devices subcutaneously, they can also can be utilized as a biomarker of core body temperature inserted in vaginal sponges.

Meta-analysis and meta-regression of core body temperature in taurine and zebuine cattle under different environmental conditions

Heat stress affects livestock productivity and is often determined by an increase in the core body temperature (CBT). To evaluate the latter, both vaginal and rectal temperatures can be used. The aims of this study were (1) to perform a meta-analysis in order to evaluate the impact of heat stress in comparison to thermoneutral conditions on CBT in Bos taurus and Bos taurus indicus cattle, and (2) to evaluate the effects of genetic group, sex, productive purpose, climate zone, and temperature-humidity index (THI class) heat stress on the vaginal and rectal temperatures of cattle. Eighty-nine studies were included in this meta-analysis. Systematic review and meta-analysis were performed following the PRISMA guidelines. The standardized mean difference (SMD) in CBT between the heat stress (HS) and thermoneutral (TN) environments was used as a measure of effect size, considering a 95% confidence interval (CI). Cochran's Q test and I² statistic indicated high variability among studies; thus, a random effects model was used. Subgroup and meta-regression analysis were performed to investigate the source of heterogeneity. Genetic group, sex, productive purpose, climate zone, and THI class were included as covariates. The SMD in CBT between the HS and TN environments was 7.45 °C (95%CI: 5.89;9.02 °C, P = 0.0001), indicating a physiological response to the heat stress condition. The SMD in CBT was 3.92 °C higher in Bos taurus than Bos taurus indicus animals (P < 0.05). Animals in climate zone D (warm temperate zone) showed a lower SMD in CBT than those in climate zone B (arid zone) (SMD = 4.04 ºC vs 12.38 ºC). The THI class affected the SMD in CBT (P < 0.05). The genetic group, climate zone, THI class and interaction between genetic group and climate zone explained 29.89% of the heterogeneity observed among studies. In conclusion, heat stress exposure affects the vaginal and rectal temperatures of cattle. The CBT measured by rectal and vaginal temperatures can be used to detect heat stress-induced changes in CBT. Bos taurus and Bos taurus indicus animals seem to respond differently to heat stress in terms of CBT.

PSIII-A-19 Thermotolerance and Residual Feed Intake in Bos-Indicus Influenced Beef Heifers

Abstract This study investigated the relationship between thermotolerance and residual feed intake (RFI) in Bos-indicus influenced replacement beef heifers. Multiple individual vaginal temperatures (VT) collected during the summer in Florida were used to select the most (n = 14; thermotolerant) and least (n = 13; non-thermotolerant) heat tolerant heifers to undergo a feed efficiency test in the fall. The maximum initial VT difference between groups was of 0.19 and 1.2 ± 0.065 °C (P &amp;lt; 0.01) for thermotolerant and non-thermotolerant heifers, respectively. Heifers (398 ± 11.3 kg; approximately 720 d of age) were randomly allocated to four concrete-floored pens equipped with two GrowSafe feed bunks each and received a common ad libitum total mixed ration (16.9% crude protein and 52% total digestible nutrients) for 56 d (14 d adaptation and 42 d evaluation period). Body weight (BW) was collected on d -1, 0, 14, 28, 41, and 42, while VT was recorded (10 min intervals for 4 consecutive d) from d 29 to 32, using temperature probes placed intravaginally with a hormone-free controlled internal drug release device. Final BW, average daily gain (ADG), dry matter intake (DMI), DMI as a percentage of BW, RFI, and VT were analyzed as a completely randomized design. Final BW, ADG, DMI, and VT collected during the feeding period were not affected by thermotolerance phenotype (P ≥ 0.42); however, heifers previously classified as thermotolerant had decreased RFI (P = 0.01; -1.32 vs. 1.27 ± 3.31 kg, respectively) and DMI as a percentage of BW (P = 0.01) when compared with non-thermotolerant heifers. In conclusion, Bos-indicus influenced replacement beef heifers previously classified as thermotolerant based on multiple vaginal temperature measurements collected throughout the summer had decreased residual feed intake when measured in the fall, indicating the potential of more heat tolerant heifers to be more feed efficient.

PSXIII-B-5 Early Gestation Heat Stress Improved Measures of sow Growth Performance but did not Impact Fetal Growth

Abstract In utero heat stress negatively impacts fetal development and alters postnatal phenotypes in swine. However, the effects of heat stress (HS) on fetal growth during early gestation is relatively unknown. The study objective was to evaluate the effects of gestational HS on measures of fetal growth in early gestation. Twenty-three gestating gilts were exposed to HS (n = 12; cyclic 26-38°C) or thermoneutral (TN; n = 11; 18.5 ± 1.2°C) conditions from gestation d 6 ± 0.9 to 33 ± 1.7. Vaginal temperature was recorded in 15 min intervals using data loggers. Respiration rates (RR) were recorded daily at 0800, 1200, 1600, and 2000 h. All gilts were individually-housed, and limit-fed 1.82 kg/d. Gilt body weights (BW) were measured weekly and average daily gain and gain:feed were calculated. At gestation d 33 ± 1.7, gilts were harvested and fetal weights and counts were recorded. Data were analyzed using PROC GLIMMIX. Vaginal temperatures and RR were greater (P &amp;lt; 0.01) in HS (38.5 ± 0.1°C and 59 ± 2 bpm, respectively) versus TN gilts (38.0 ± 0.1°C and 29 ± 2 bpm, respectively). Although no initial BW differences were observed (P = 0.39; 148.8 ± 4.1 kg), final BW tended to be greater (P &amp;lt; 0.07) for HS (166.5 ± 3.8 kg) versus TN (156.8 ± 4.0 kg) gilts. Average daily gain was increased (P &amp;lt; 0.01) for HS (0.5 ± 0.1 kg/d) versus TN (0.3 ± 0.1 kg/d) gilts. Gain:feed was greater (P &amp;lt; 0.01) for HS (0.27 ± 0.03) versus TN (0.16 ± 0.03) gilts. No fetal weight (P = 0.23; 4.3 ± 0.2 g/fetus) or count (P = 0.15; 15.2 ± 0.9 fetuses/gilt) differences were detected. In conclusion, HS-exposure during early gestation improved measures of growth performance in gestating gilts but did not impact fetal growth or count.

PSIV-A-3 Body Temperature Monitoring Using Subcutaneously and Vaginal Sensors in Grazing Cows

Abstract Body temperature is an indicator of animal health and can be used to detect harmful physiological events in advance of clinical symptoms. Traditionally, body temperature in cattle is determined with a rectal thermometer and requires the animal to be restrained. Although systems to automatically monitor cattle health in confinement operations exist, assessing the real-time temperature of grazing cows is not common. Our object was to demonstrate an integrated sensor network for monitoring pastured cattle body temperature in comparison with temperature measured by a vaginal logger. The integrated sensor network (Mahindra &amp; Mahindra; Mumbai, India) communicates with the data obtained from a subcutaneous temperature sensor (EmbediVet, Livestock Labs Inc.; Pittsburg, PA) to a cloud-based data storage platform. The vaginal temperature was measured by an implantable temperature logger (Micro-T 16-bit; Star Oddi, Iceland). Vaginal devices were inserted into the vagina using a controlled internal drug release (CIDR) cleaned of progesterone. The subcutaneous temperature sensors were surgically implanted through a 2cm vertical incision in the neck. Data from the implantable sensor were transmitted via Bluetooth communication to a solar-powered base station. The subcutaneous sensors and vaginal loggers were deployed on 10 grazing cattle over a period of 6 months. Data from only 4 subcutaneous sensors consistently reported data. Temperature values measured by the subcutaneous sensors had no statistical relationship (P=0.595) with body temperature measured by the vaginal temperature loggers. However, the subcutaneous sensors were able to detect changes in body temperature over time within-animal, indicating that errors in predicting temperature were more likely due to frameshift issues than an inability to track true temperature. Further improvements in data-processing and higher sample size are needed to maximize the usability of this sensor network for monitoring cattle body temperature.

PSVI-20 Effect of Skin Thickness and Rumen-Protected Methionine on Body Temperature of Nelore Cows Keep on Tropical Environment

Abstract The aim of this study was to evaluate the effect of rumen-protected (RPM) supplementation on body temperature, as well as the relationship between skin thickness and body temperature of Nelore cows in a tropical climate. The study was carried out at the Hildegard Georgina Von Pritzelwitz Agrozootechnical Experimental Station (Fazenda Figueira), located in southern Brazil (23º34'26" S; 50º58'14" W), during the 2020/2021 breeding season. In the period from d-28, 28 days after the FTAI protocol, the animals were divided into 2 treatments: the Control Group (CG) receiving 100g/cow/day of mineral salt, and the Methionine group (MG) with the same mineral salt supplementation plus 3g RPM. Between d-9 and d-2 FTAI the body temperature was measured using a data logger coupled to the progesterone device, with assessment of vaginal temperature every 30 minutes. The skin was measured in millimeters (mm) with a cutimeter in the scapular region at the same day of pregnancy diagnosis (d28). The mean plus one standard deviation of the skin thickness was used to categorize the animals with thick skin and thin skin corresponding to (CG: 5.09% of 530 animals; GM: 5.28% of 530 animals) leaving a total of 55 animals in total, GC=27 and MG=28. Data were analyzed using Mixed Models in JMP, considering the body temperature as the random variable; group, day, quartile and their interactions with fixed effects; animals were included as a random effect. Body temperature was different between GC (38.878±0.028) and GM (38.784±0.028), P&amp;lt; 0.05. The interaction between group and skin category was different between GC-thin skin (38.92±0.041) and MG-thin skin (38.74±0.037; P&amp;lt; 0.05), the other categories showed no difference (P &amp;gt; 0.05). The other evaluations did not show difference (P &amp;gt;0.05). In conclusion, methionine was able to reduce the internal body temperature of Nelore cows at tropical temperatures, mainly in those with thin skin thickness.

395 Young Scholar Award Talk: Melatonin: A Promising Therapeutic for Compromised Pregnancies

Abstract Poorly functioning placenta restricts oxygen and nutrient supply to the fetus resulting in fetal nutrient deficiency and intrauterine growth restriction. Intrauterine growth restriction dramatically increases neonatal mortality and those who survive are more prone to experience metabolic diseases such as cardiovascular diseases, hypertension, and type 2 diabetes in later life. Therefore, the placenta plays a critical role in the developmental origins of health and diseases. Currently, there is a vast effort evaluating the effects of compromised pregnancies such as maternal undernutrition, overnutrition, and heat stress on fetal development; however fewer studies have evaluated potential therapeutics to enhance placental efficiency and offspring performance. Melatonin, a hormone that modulates circadian rhythms, has shown to increase umbilical and uterine blood flow in pregnant dams. Moreover, a recent study observed that melatonin therapeutic effects during compromised pregnancies are seasonally dependent. Dietary melatonin supplementation to pregnant beef cattle increased uterine blood flow, rescued fetal weights, increased angiogenic factors in the placenta, and reduced vaginal temperatures in the summer, but not in the fall. The same study found that maternal nutrient restriction was more detrimental during the fall reducing uterine blood flow. Additionally, it was observed that dams that are nutrient restricted during the summer exerted a compensatory mechanism at the placentome level where they exhibited greater placentome vascularity and increased placental capillary size and angiogenic factors. Lastly, bovine placental circadian rhythms have been identified and interestingly, temporal increases in placental vascularity occur concomitantly with greater melatonin receptor 1A transcript abundance. In conclusion, these findings provide a better understanding of placental insufficiency and impaired fetal growth during maternal nutrient restriction, while temporal alterations in the placenta could lead to the development of proper guidelines for administration of placental blood flow therapeutics such as melatonin. Future studies should evaluate melatonin impacts on offspring organ development and potential for mitigating heat stress in livestock.

Effectiveness of the Australian breeding value for heat tolerance at discriminating responses of lactating Holstein cows to heat stress.

Heat stress has negative consequences for milk production and reproduction of dairy cattle. These adverse effects are likely to increase because of climate change and anticipated increases in milk yield. Some of the variation among cows in ability to resist effects of heat stress is genetic. The current objective of this observational study was to assess the effectiveness of the Australian breeding value for heat tolerance (ABVHT) based on the decline in milk yield with heat stress for predicting cow differences in effects of heat stress on regulation of body temperature, milk production, and reproductive function. Genomic breeding values for heat tolerance were calculated for 12,487 cows from a single California dairy farm. Rectal temperature in the afternoon (1100-2045 h) was measured on a subset of 626 lactating cows with ABVHT ≥102 (heat tolerant) or <102 (heat sensitive). Rectal temperature was 0.12°C lower for heat-tolerant cows than heat-sensitive cows. Vaginal temperatures were measured every 15 min for 5 d in 118 cows with ABVHT ≥108 (extreme heat tolerant) or <97 (extreme heat sensitive). Vaginal temperature was 0.07°C lower for extreme heat-tolerant cows than extreme heat-sensitive cows. Lactation records for 4,703 cows with ABVHT were used to evaluate seasonal variation in first 90-d milk yield, fat percent, and protein percent for each ABVHT quartile. Overall, cows with higher ABVHT had lower milk yield, fat percentage, and protein percentage and higher first service pregnancy rate. There was no summer depression in production or reproduction or interactions between season and ABVHT quartile. We observed that ABVHT can successfully identify heat-tolerant cows that maintain lower body temperatures during heat stress. The lack of a pronounced seasonality in milk production or reproduction precluded evaluation of whether ABVHT is related to the magnitude of effect of heat stress on those traits.

The protective role of wallowing against heat stress in gestating and lactating sows housed outdoors

The objective of this study was to describe the physiological response of gestating and lactating sows to naturally-occurring environmental conditions, and to identify factors that may contribute to or prevent heat stress, while being kept outdoors in Québec, Canada during the summer. Six groups of 4 Yorkshire-Landrace sows lived in outdoor pens equipped with a wallow, shade structure, farrowing huts and access to a pasture from July to September 2018. Between week 15 of gestation and week 3 of lactation (inclusive), we recorded the location of each sow 5 days/week during 5 daily 15-min observation periods, and additionally measured the sow's respiratory rate and mud cover at the end of each observation period. Simultaneously, we collected sow body temperature data with vaginal temperature loggers 24 h/d on week 15 of gestation and week 2 of lactation, and monitored environmental conditions with temperature and humidity loggers to calculate the temperature humidity index (THI). Sows had significantly higher and more variable body temperatures during lactation compared to gestation (P ≤ 0.0001), and when THI was analysed as a continuous variable, it was positively associated with sow body temperature during the night in lactation. During gestation, neither respiratory rate nor body temperature were associated with high or low levels of THI (P = 0.15 and 0.79, respectively) or mud cover (P = 0.29 and 0.94, respectively). However, in lactation, respiratory rate was higher when, simultaneously, THI exceeded 74 and mud cover was low (P = 0.006), while a THI higher than 74 and a low mud cover had independent effects on body temperature (P = 0.012 and 0.004, respectively). In lactation, sows that spent an entire observation period in the farrowing hut also had a higher respiratory rate than sows that left the hut at least once (P = 0.009). In summary, lactating sows were more likely to show increases in respiratory rate and body temperature in warmer conditions than gestating sows, and our findings also suggest that time in the farrowing hut may be a risk factor for heat stress. However, mud cover may limit these physiological consequences when sows have access to a wallow.

191 Improving Climatic Resilience in Pigs Through Physiological Genomics

Abstract Breeding programs have improved productive and reproductive efficiency in worldwide swine populations. However, greater performance is often accompanied by reduced climatic resilience due to greater metabolic heat production. Genomic selection is an effective tool for alleviating the negative effects of heat stress, but it requires traits that effectively capture the physiological, behavioral, and morphological mechanisms regulating the heat stress response. In this presentation we will first describe the genetic background of heat tolerance based on routinely recorded phenotypes (growth, carcass composition, and reproduction) and climatic variables obtained from public-weather-station databases. There are clear genotype-by-environment interactions across environmental conditions and the definition of the critical periods for quantifying the environmental gradient directly impacts the accuracy of genomic prediction of breeding values for heat tolerance. Secondly, we will describe the genetic background of various behavioral, physiological, and morphological indicators of heat stress in maternal line pigs, including automatically recorded vaginal temperature, skin temperature measured in different body locations and times of the day, respiration rate, panting score, body condition score, hair cortisol, hair density, and ear area. These traits are heritable and can be successfully included in genomic breeding programs. Furthermore, we will discuss the transgenerational effects of heat stress in maternal-line pigs, including an epigenomic analyses of in-utero heat stress that identified over 200 genomic regions that are differentially methylated. In summary, we will: 1) provide a comprehensive description of the environmental-gradient variables and critical periods fitted in genomic evaluations of heat tolerance; 2) describe the genetic background of various indicators of heat tolerance, including heritability, genetic correlations, candidate genes, differentially-methylated regions, and metabolic pathways associated with the significant genomic regions; 3) present the accuracies of genomic predictions for each indicator trait; and, 5) make recommendations for the implementation of genomic selection for improved heat tolerance in pigs. This research was supported by the Agriculture and Food Research Initiative (AFRI) Competitive Grants number 2020-67015-31575 and 2021-67015-34458 from the USDA National Institute of Food and Agriculture.

Evaluation of environmental and physiological indicators in lactating dairy cows exposed to heat stress.

This study aimed to better understand environmental heat stress and physiological heat strain indicators in lactating dairy cows. Sixteen heat stress indicators were derived using microenvironmental parameters that were measured at the surrounding of cows and at usual fixed locations in the barn by using handheld and fixed subarea sensors, respectively. Twenty high-producing Holstein-Friesian dairy cows (> 30.0kg/day) from an intensive dairy farm were chosen to measure respiration rate (RR), vaginal temperature (VT), and body surface temperature of forehead (FT), eye (ET), and muzzle (MT). Our results show that microenvironments measured by the handheld sensor were slightly warmer and drier than those measured by the fixed subarea sensor; however, their derived heat stress indicators correlated equally well with physiological indicators. Interestingly, ambient temperature (Ta) had the highest correlations with physiological indicators and the best classification performance in recognizing actual heat strain state. Using segmented mixed models, the determined Ta thresholds for maximum FT, mean FT, RR, maximum ET, mean ET, VT, mean MT, and maximum MT were 24.1°C, 24.2°C, 24.4°C, 24.6°C, 24.6°C, 25.3°C, 25.4°C, and 25.4°C, respectively. Thus, we concluded that the fixed subarea sensor is a reliable tool for measuring cows' microenvironments; Ta is an appropriate heat stress indicator; FT, RR, and ET are good early heat strain indicators. The results of this study could be helpful for dairy practitioners in a similar intensive setting to detect and respond to heat strain with more appropriate indicators.