Low Temperature-humidity Index Research Articles

Association between a pyroelectric infrared sensor monitoring system and a 3-dimensional accelerometer to assess movement in preweaning dairy calves

The objective of this study was to correlate movement assessed by a pyroelectric infrared sensor system in preweaning dairy calves with lying and standing time assessed by a 3D accelerometer considering the temperature-humidity index (THI). A total of 35 dairy calves (1–7 d of age) were enrolled in the study and 20 calves were included in the final analyses. The lying and standing time of the calves was monitored with a 3D accelerometer (Hobo Pendant G Data Logger, Onset Computer Corporation, USA), which was used as the gold standard reference. The infrared sensor monitoring system (IMS; Calf Monitoring System, Futuro Farming GmbH, Germany) was fixed to the fence of the calf hutch within the calf's reach. Temperature-humidity was monitored with 2 validated THI sensors inside and on outside of each calf hutch. Additionally, one THI sensor was located near the calf hutches. The observation period lasted 14 consecutive days. The average standing time assessed by the 3D accelerometer was 13.4 ± 12.7 (mean ± standard deviation) min/h and the average lying time was 46.6 (±12.7) min/h. The median (25th percentile; 75th percentile) number of movements measured by the IMS was 360 (60; 919) movements per hour. Number of movements per hour measured by the IMS was compared with data obtained with a validated 3D accelerometer. The Pearson correlation coefficient between both standing and lying time and the number of movements was r = 0.85 and r = −0.85, respectively. The Pearson correlation coefficients were only slightly influenced by THI (low THI [<68]: r = 0.86; medium THI [68–72]: r = 0.85; high THI [>72]: r = 0.81). Our data show that the number of movements of dairy calves measured by IMS were highly correlated with the chosen gold standard reference method. High THI slightly affects the measurement accuracy of IMS.

Comparing thermal conditions inside and outside lactating dairy cattle barns in Canada

The health, longevity, and performance of dairy cattle can be adversely affected by heat stress. This study evaluated the in-barn condition [i.e., temperature, relative humidity, and resulting temperature-humidity index (THI)] at 9 dairy barns with various climates and farm design-management combinations. Hourly and daily indoor and outdoor conditions were compared at each farm, including both mechanically and naturally ventilated barns. On-site conditions were compared with on-farm outdoor conditions, meteorological stations up to 125 km away, and NASA Power data. Canadian dairy cattle face periods of extreme cold and periods of high THI, dependent on the regional climate and season. The northernmost location (53°N) experienced about 75% fewer hours of THI >68 compared with the southernmost location (42°N). Milking parlors had higher THI than the rest of the barn during milking times. The THI conditions inside dairy barns were well correlated with THI conditions measured outside the barns. Naturally ventilated barns with metal roofs and without sprinklers fit a linear relationship (hourly and daily means) with a slope <1, indicating that in-barn THI exceeded outdoor THI more at lower THI and reached equality at higher THI. Mechanically ventilated barns fit nonlinear relationships, which showed the in-barn THI exceeded outdoor THI more at lower THI (e.g., 55-65) and approached equality at higher THI. In-barn THI exceedance was greater in the evening and overnight due to factors such as decreased wind speed and latent heat retention. Eight regression equations were developed (4 hourly, 4 daily) to predict in-barn conditions based on outdoor conditions, considering different barn designs and management systems. Correlations between in-barn and outdoor THI were best when using the on-site weather data from the study, but publicly available weather data from stations within 50 km provided reasonable estimates. Climate stations 75 to 125 km away and NASA Power ensemble data gave poorer fit statistics. For studies involving many dairy barns, the use of NASA Power data with equations for estimating average in-barn conditions in a population is likely appropriate especially when public stations have incomplete data. Results from this study show the importance of adapting recommendation on heat stress to the barn design and guide the selection of appropriate weather data depending on the aim of the study.

Haemo-thermoregulatory response of wallowed and non-wallowed geese during low temperature humidity index

Abstract Haemo-thermoregulatory response of twenty-six adult geese comprising of 12 males and 14 females randomly allotted to four groups (Wallowed males, non-wallowed males, wallowed females and non-wallowed females) in a completely randomized design for seven weeks was evaluated. Wallowing was done every alternate day. Respiratory rate (RR), rectal temperature (RT) and pulse rate (PUR) were recorded. On days 1 and 49, blood samples (3mL/geese) were collected from geese in each group and analysed for haematological parameters using standard procedures. There was no sex effect on the RR and PUR but significantly (p&lt;0.05) higher RT was observed in males (40.69°C) compared to females (40.53°C). The RR, RT and PUR were not significantly affected by wallowing. Interactions effect between sex and wallowing on RR, RT and PUR was not significant. Only platelet counts were significantly higher in females (17.70) than males (14.68). Wallowed Geese had significantly lower packed cell volume (37.46±5.13%), haemoglobin (11.85±1.69g/dl) and monocytes (2.81±0.63%) than other treatments. Wallowed Female geese had significantly lower haemoglobin (10.93g/dL) and monocytes (2.86%) compared to those without wallow treatment. Therefore, wallowing has mild influence on the thermoregulatory and haematological indices of geese reared under low temperature-humidity index during non-breeding season.

Air Quality, Management Practices and Calf Health in Italian Dairy Cattle Farms.

Simple SummaryCalf mortality is an important factor of economic loss in dairy operations. Among the factors which can affect calf health, air quality in calf housing has rarely been studied. In the present research, the relations among air quality in the calf pens, management practices, microclimatic conditions and calf health and mortality were studied in 25 Italian dairy cattle farms. Microbial air quality in the calf pens was found to be related to temperature and humidity, design and position of the pen, some management practices and calf health and mortality. Maintaining dry bedding and controlling microclimatic conditions in the calf pen can be useful practices to promote good air microbiological quality in the calf pen, improving calf health and reducing mortality.Among factors that can affect calf health, microbial quality of the pen air is poorly studied. In 25 Italian dairy farms, data concerning air quality in the calf pens, hygiene of pens and equipment, microclimatic conditions, calf health and management were collected during the winter season (January-March 2020 and December-March 2021). The average air Standard Plate Count (SPC) of 85 pens was 4.51 (SD = 0.52) log10 cfu/m3 whereas the average air ammonia concentration was 0.66 (SD = 0.53) ppm. Positive correlations were found between average Temperature Humidity Index (THI) in the pen and air SPC, night maximum THI and air SPC and between SPC and yeast, mould and ammonia concentration in the pen air. The concentrations of E. coli, Enterobacteriaceae and yeasts in the pen air were higher and calf cough increased as the renewal interval of bedding material became longer. High bedding dry matter and low THI were associated with low air SPC, good calf health scores and low mortality. Maintaining low bedding humidity and controlling microclimatic conditions can contribute to enhancing air microbiological quality in the pen and reduce calf diseases and mortality.

Possible Consequences of Climate Change on Survival, Productivity and Reproductive Performance, and Welfare of Himalayan Yak (Bos grunniens).

Simple SummaryClimate change is a global issue, with a wide range of ecosystems being affected by changing climatic conditions including the Himalaya. Yak are exquisitely adapted to the high-altitude conditions of the Himalaya and are thus highly likely to be affected by climate change. This paper reviews the evidence of how the reported impacts of climate change on the environment and ecosystem of the Himalaya are affecting the survival, productivity and welfare of Himalayan Yak. This review identified that we do not know how big the impact of climate change is on yak as very few papers have measured that impact and, in many cases, potentially climate-change-related effects (such as changes in feed supply) are principally driven by human factors.Yak are adapted to the extreme cold, low oxygen, and high solar radiation of the Himalaya. Traditionally, they are kept at high altitude pastures during summer, moving lower in the winter. This system is highly susceptible to climate change, which has increased ambient temperatures, altered rainfall patterns and increased the occurrence of natural disasters. Changes in temperature and precipitation reduced the yield and productivity of alpine pastures, principally because the native plant species are being replaced by less useful shrubs and weeds. The impact of climate change on yak is likely to be mediated through heat stress, increased contact with other species, especially domestic cattle, and alterations in feed availability. Yak have a very low temperature humidity index (52 vs. 72 for cattle) and a narrow thermoneutral range (5–13 °C), so climate change has potentially exposed yak to heat stress in summer and winter. Heat stress is likely to affect both reproductive performance and milk production, but we lack the data to quantify such effects. Increased contact with other species, especially domestic cattle, is likely to increase disease risk. This is likely to be exacerbated by other climate-change-associated factors, such as increases in vector-borne disease, because of increases in vector ranges, and overcrowding associated with reduced pasture availability. However, lack of baseline yak disease data means it is difficult to quantify these changes in disease risk and the few papers claiming to have identified such increases do not provide robust evidence of increased diseases. The reduction in feed availability in traditional pastures may be thought to be the most obvious impact of climate change on yak; however, it is clear that such a reduction is not solely due to climate change, with socio-economic factors likely being more important. This review has highlighted the large potential negative impact of climate change on yak, and the lack of data quantifying that impact. More research on the impact of climate change in yak is needed. Attention also needs to be paid to developing mitigating strategies, which may include changes in the traditional system such as providing shelter and supplementary feed and, in marginal areas, increased use of yak–cattle hybrids.

Heat stress in a temperate climate leads to adapted sensor-based behavioral patterns of dairy cows

Most research on heat stress has focused on (sub)tropical climates. The effects of higher ambient temperatures on the daily behavior of dairy cows in a maritime and temperate climate are less studied. With this retrospective observational study, we address that gap by associating the daily time budgets of dairy cows in the Netherlands with daily temperature and temperature-humidity index (THI) variables. During a period of 4 years, cows on 8 commercial dairy farms in the Netherlands were equipped with neck and leg sensors to collect data from 4,345 cow lactations regarding their daily time budget. The time spent eating, ruminating, lying, standing, and walking was recorded. Individual cow data were divided into 3 data sets: (1) lactating cows from 5 farms with a conventional milking system (CMS) and pasture access, (2) lactating cows from 3 farms with an automatic milking system (AMS) without pasture access, and (3) dry cows from all 8 farms. Hourly environment temperature and relative humidity data from the nearest weather station of the Dutch National Weather Service was used for THI calculation for each farm. Based on heat stress thresholds from previous studies, daily mean temperatures were grouped into 7 categories: 0 = (<0°C), 1 = (0-12°C, reference category), 2 = (12-16°C), 3 = (16-20°C), 4 = (20-24°C), 5 = (24-28°C), and 6 = (≥28°C). Temperature-humidity index values were grouped as follows: 0 = (THI <30), 1 = (THI 30-56, reference category), 2 = (THI 56-60), 3 = (THI 60-64), 4 = (THI 64-68), 5 = (THI 68-72) and 6 = (THI ≥72). To associate daily mean temperature and THI with sensor-based behavioral parameters of dry cows and of lactating cows from AMS and CMS farms, we used generalized linear mixed models. In addition, associations between sensor data and other climate variables, such as daily maximum and minimum temperature, and THI were analyzed. On the warmest days, eating time decreased in the CMS group by 92 min/d, in the AMS group by 87 min/d, and in the dry group by 75 min/d compared with the reference category. Lying time decreased in the CMS group by 36 min/d, in the AMS group by 56 min/d, and in the dry group by 33 min/d. Adaptation to daily temperature and THI was already noticeable from a mean temperature of 12°C or a mean THI of 56 or above, when dairy cows started spending less time lying and eating and spent more time standing. Further, rumination time decreased, although only in dry cows and cows on AMS farms. With higher values for daily mean THI and temperature, walking time decreased as well. These patterns were very similar for temperature and THI variables. These results show that dairy cows in temperate climates begin to adapt their behavior at a relatively low mean environmental temperature or THI. In the temperate maritime climate of the Netherlands, our results indicate that daily mean temperature suffices to study the effects of behavioral adaptation to heat stress in dairy cows.

Impact of heat stress on reproductive performance of Sahiwal cows

The objective of the present study was to investigate the effect of temperature humidity index (THI) and indicator of heat stress on reproductive performance i.e. calving interval, conception rate and pregnancy rate of Sahiwal cows maintained under Livestock Research Center, National Dairy Research Center, Karnal. A total calving record pertaining to 3000 lactations of 847 Sahiwal cows, spread over 26 years from 1990 to 2015 from were considered for the present study. The daily ambient temperature and relative humidity records were collected from Central Soil Salinity and Research Institute, Karnal and NICRA center (Climate Resilient Livestock Research Center), NDRI, Karnal. All statistical procedures were performed using SAS Statistical Package. A univariate logistic regression model was fitted to assess the effect of independent variable THI on the dependent variables conception and pregnancy status. A distinct relationship between THI and calving interval was observed in the present study, the cows had a significant longer calving interval at high THI as compared with low THI. It was observed that the average calving interval was increased by 2 days with per unit increase in THI value. Pregnancy rate and Conception rate of Sahiwal animals was significantly reduced from 35% at low THI to 18% at high THI and from 55% at low THI to 26% at high THI respectively with decreasing odd ratio. In conclusion high environmental temperature reduces the reproductive performance of animals and significantly influences the animal productivity.

PSXII-6 Landscape genetics used to identify gene bank beef cattle collection completeness and gaps

Abstract Gene banks (GB) primary goal is to capture genetic diversity among livestock breeds. Genetic diversity assessments by US GB have used pedigrees and genetic markers. Landscape genetics (LG), is a third approach for evaluating germplasm collections and genetic resources. We evaluated the GB’s beef collection using LG for the purpose of assessing collection gaps/completeness by using geographic information systems. The current beef cattle collection contains 3,916 animals from 11 Bos indicus (including composite, BI), and 40 Bos taurus British (BTB) and Bos taurus continental (BTC) breeds. Each GB animal was georeferenced by latitude and longitude. In addition, county level satellite imagery of the continental US was obtained and included: temperature, humidity, precipitation, and normalized difference vegetation index (NDVI). Temperature–humidity index (THI) was computed from temperature and humidity by county. In addition, USDA beef cattle statistics by county were used in mapping overlays. There was a high correspondence between in-situ cattle density and GB collection throughout the mid-west and extending to both borders. Evaluating genetic groups demonstrated that BI were derived from the Gulf Coast region, while BTB and BTC shared a distribution throughout the mid-west. The collection’s BTB were also sourced from the inter-mountain west. All environmental parameters were combined to identify similar environmental conditions where germplasm had already been collected. Through this process future geographies for sampling genetic groups were apparent. New collection areas should include the Great Basin, west Texas, New Mexico and Arizona. Further BI collections should be performed in low THI score areas and BTB and BTC collections in high THI areas is needed. Using GIS/LG adds a new perspective and resolution for future collections to ensure cattle that are adapted to a particular environment are added to the collection.

The impact of weather on the incidence of dark cutting in Australian feedlot cattle.

This study conducted a retrospective analysis of historical Meat Standard Australia (MSA) carcass data in combination with Bureau of Meteorology (BOM) weather data, to evaluate the relationship between climatic conditions prior to feedlot departure on the incidence of dark cutting grain-fed beef. Data records for 2,795,754 carcasses from 17 commercial feedlots over a 6-year period were evaluated within this study. Carcasses were consigned to 16 abattoirs. Weather data from BOM were recorded at 30-min intervals and were obtained from weather stations with the closest proximity to each feedlot. These data were used to calculate the Temperature Humidity Index (THI). Climatic data were amalgamated into daily observations and a series of predictors including ambient temperature (TA, °C), relative humidity (RH, %), wind speed (WS, m/s), rainfall (mm) and THI. In addition, lag interactions from 24h out to 28days prior to exiting the feedlot were generated. The incidence of dark cutting was determined as percentage per cohort with an ultimate pH > 5.7. Data were analysed using three models: model 1 included feedlot, abattoir, hormone growth promotant status and sex as fixed effects. Model 2 incorporated the fixed effects within model 1 and minimum, maximum and standard deviation (SD) of TA and RH, daily range in TA, average WS and rainfall as random effects. Model 3 incorporated minimum, maximum, range and SD of THI, average WS and rainfall as random effects in addition to the fixed effects of model 1. The incidence of dark cutting within feedlot had a 10.1% range in estimated means with the lowest incidence was observed at feedlot 17 (0%) and highest incidence at feedlot 10 (10.1%). The inclusion of the climatic variables in model 2 and model 3 accounted for an additional 0.1 to 0.2% of the incidence of dark cutting carcasses. Higher maximum TA, RH and THI in the 3 to 28days prior to consignment were all associated with an increased incidence of dark cutting (P < 0.05), but not in the 48h preceding consignment (P > 0.05). Low minimum TA and low THI were also associated with an increase the incidence of dark cutting across all lag periods (P < 0.05). Increased variation in THI and TA in the 48h prior to consignment increased dark cutting (P < 0.05) while increased standard deviation (SD) of temperature and THI range also increased dark cutting in the 14 and 28day prior to feedlot exit (P < 0.05). Smaller minimum ranges in TA in the 28days prior to consignment also reduced dark cutting (P < 0.05). Climatic conditions accounted for a further 0.1 to 0.2% of the incidence of dark cutting, whereas animal management factors, feedlot and abattoir were able to account for 21% of dark cutting. These data suggest that climatic conditions appear to have an inherent role in the incidence of dark cutting, albeit a small impact. Regardless, understanding the influence of climatic conditions on dark cutting allows for the implementation of management strategies within the supply chain to further reduce the impact of climatic conditions on grain-fed cattle.

Semen analysis of boars under intertropical conditions reveals the relevance of proximal and distal cytoplasm droplets for sperm functional integrity.

This work aimed to establish whether the temperature humidity index (THI) under different intertropical zones affects the retention of cytoplasmic droplets (CDs), sperm function and DNA integrity in boars. With this purpose, two separate studies were devised. In the first one, 49 boars from six farms were collected every 45days (230 ejaculates). THI were measured daily, and sperm parameters were evaluated. Boars were classified into three groups based on the incidence of ejaculates having more than 25% spermatozoa with CDs: persistent (at least three consecutive ejaculates), moderate (less than three ejaculates) and absent (no ejaculate having ≥25% spermatozoa with CDs). Farms were classified based on THI through cluster analysis into two groups. In the second study, 32 liquid-stored semen samples were classified based on three cluster analysis: low and high incidence of proximal (PCDs), distal (DCDs) CDs and a combination of PCD and DCDs. high THI farms presented significantly (p<.05) higher proportions of boars with moderate and persistent incidence of CD than those with low THI. In study 2, the presence of PCDs was negatively correlated with sperm DNA integrity (r=-0.691; p<.01). However, differences between groups were more apparent when ejaculates were classified based on both PCDs and DCDs than when PCDs or DCDs were considered separately. In conclusion, classification of boars according to the severity and persistence of CDs in boars allows understanding more clearly the dynamics of CD retention and the effects of ambient temperature and relative humidity. Additionally, the joint analysis of both PCDs and DCDs is necessary in routine sperm quality analyses.

Climate sensitivity of milk production traits and milk fatty acids in genotyped Holstein dairy cows

The aim of this study was the evaluation of climate sensitivity via genomic reaction norm models [i.e., to infer cow milk production and milk fatty acid (FA) responses on temperature-humidity index (THI) alterations]. Test-day milk traits were recorded between 2010 and 2016 from 5,257 first-lactation genotyped Holstein dairy cows. The cows were kept in 16 large-scale cooperator herds, being daughters of 344 genotyped sires. The longitudinal data consisted of 47,789 test-day records for the production traits milk yield (MY), fat yield (FY), and protein yield (PY), and of 20,742 test-day records for 6 FA including C16:0, C18:0, saturated fatty acids (SFA), unsaturated fatty acids (UFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). After quality control of the genotypic data, 41,057 SNP markers remained for genomic analyses. Meteorological data from the weather station in closest herd distance were used for the calculation of maximum hourly daily THI. Genomic reaction norm models were applied to estimate genetic parameters in a single-step approach for production traits and FA in dependency of THI at different lactation stages, and to evaluate the model stability. In a first evaluation strategy (New_sire), all phenotypic records from daughters of genotyped sires born after 2010 were masked, to mimic a validation population. In the second strategy (New_env), only daughter records of the new sires recorded in the most extreme THI classes were masked, aiming at predicting sire genomic estimated breeding values (GEBV) under heat stress conditions. Model stability was the correlation between GEBV of the new sires in the reduced data set with respective GEBV estimated from all phenotypic data. Among all test-day production traits, PY responded as the most sensitive to heat stress. As observed for the remaining production traits, genetic variances were quite stable across THI, but genetic correlations between PY from temperate climates with PY from extreme THI classes dropped to 0.68. Genetic variances in dependency of THI were very similar for C16:0 and SFA, indicating marginal climatic sensitivity. In the early lactation stage, genetic variances for C18:0, MUFA, PUFA, and UFA were significantly larger in the extreme THI classes compared with the estimates under thermoneutral conditions. For C18:0 and MUFA, PUFA, and UFA in the middle THI classes, genetic correlations in same traits from the early and the later lactation stages were lower than 0.50, indicating strong days in milk influence. Interestingly, within lactation stages, genetic correlations for C18:0 and UFA recorded at low and high THI were quite large, indicating similar genetic mechanisms under stress conditions. The model stability was improved when applying the New_env instead of New_sire strategy, especially for FA in the first stage of lactation. Results indicate moderately accurate genomic predictions for milk traits in extreme THI classes when considering phenotypic data from a broad range of remaining THI. Phenotypically, thermal stress conditions contributed to an increase of UFA, suggesting value as a heat stress biomarker. Furthermore, the quite large genetic variances for UFA at high THI suggest the consideration of UFA in selection strategies for improved heat stress resistance.

Effect of seasonal thermal stress on oxidative status, immune response and stress hormones of lactating dairy cows.

This study aimed to assess the impact of seasonal thermal stress on oxidative stress, immune response, and stress hormones of lactating dairy cows in subtropical regions with different levels of temperature-humidity index (THI). A total of 32 healthy lactating Holstein dairy cows experienced 4 seasons (8 cows/season). The physiological parameters were categorized into low THI (LTHI, THI = 42.97 ± 0.95) in winter, moderate THI (MTHI, THI = 61.84 ± 0.42) in spring and autumn, and high THI period (HTHI, THI = 86.09 ± 0.23) in summer. The blood samples were collected twice in each season to measure oxidative stress, inflammatory and hormonal parameters. Our results showed THI had a positive correlation with the rectal temperature (R2 = 0.821, P < 0.001) and respiratory rate (R2 = 0.816, P < 0.001). Dry matter intake, milk yield and fat percentage also significantly differed among groups (P < 0.05). Compared with the MTHI group, the LTHI group exhibited a significant increase in malondialdehyde (MDA) level (P < 0.001), and the HTHI group displayed a significant increase in levels of cortisol, interleukin (IL)-10, IL-1β and tumor necrosis factor-α (P < 0.001). Opposite changes in serum endotoxin and immunoglobulin G levels were observed with the increasing THI (P < 0.001). LTHI notably increased the triiodothyronine level, although the thyroxine level was reduced by LTHI and HTHI compared with the MTHI group. In conclusion, LTHI and HTHI conditions may induce different degrees of oxidative stress, inflammation response, and stress hormone imbalances on lactating dairy cows, therefore environmental management is necessary for the health of dairy cows in extreme weather conditions.

Association of β-casein gene polymorphism with milk composition traits of Egyptian Maghrebi camels (Camelus dromedarius).

The objectives of this study were to detect the polymorphism of 2126 SNP in the -casein (CSN2) gene among Egyptian Maghrebi camels and to investigate the association of 2126 SNP genotypes, parity, lactation stage, and temperature–humidity index (THI) with the milk composition traits of Maghrebi camels. Sixty-eight hair samples were collected from three different populations of Maghrebi camels for DNA extraction. Fat, protein, total solids, solids-not-fat, and lactose percentages were determined in Maghrebi camel milk using an automatic milk analyzer device. Three different genotypes – A/A, A/G, and G/G – were identified in the 5 flanking region of -casein gene by using PCR-RFLP method with the A/G genotype showing the highest frequency. Association among these three genotypes with milk composition traits suggests a positive effect of A/A genotype on acidity and protein percentage. Higher protein and acidity values were observed in the milk of individuals carrying the A/A genotype. The protein percentage of this study significantly increased from the first till the fourth parity and then decreased. Fat and total solid percentages were significantly higher in the late stage of lactation, while lactose showed a decreasing trend from the early till the late stages of lactation. Fat and protein percentages were highest in the low THI class. Our results encourage the utilization of Maghrebi camel milk for cheese and butter processing at the late lactation stages of the middle parities of their productive life. Moreover, the A/G SNP of the CSN2 gene may be used as a DNA marker in selection programs for the improvement of camel milk composition. Further studies are needed in order to fully explore the variation in the chemical composition of camel milk due to the effect of CSN2 gene, parity, lactation stage, and THI factors.

Rumen-Reticular Temperature During Estrus and Ovulation Using Automated Activity Monitors in Dairy Cows.

This study aimed to determine changes in rumen-reticular temperature (RRT) at estrus or ovulation and determine if these changes are associated with the intensity of estrous expression. Cows were equipped with an automated activity monitor (AAM) and a rumen-reticular bolus thermometer. A total of 190 estrus episodes were used where physical activity data was recorded using the AAM and ovulation was determined via ultrasonography of the ovaries at alert and twice daily, for a maximum of 60 h. Estrous expression was assessed using the maximum activity and duration in which activity remained above the AAM threshold; both characteristics were categorized using the median. Temperature data was collected for the duration of estrus, as well as for the interval of time where ovulation was determined to occur. Three measures of temperature were calculated: (1) positive area under the curve (AUC), (2) maximum positive temperature change (PTC), (3) maximum negative temperature change (NTC) at estrus (AUCE/ PTCE/ NTCE) and around ovulation (AUCO/PTCO/ NTCO). Both AUC and PTC were greater during estrus than around ovulation (2.7 ± 0.2 and 1.1 ± 0.3°C2 for AUCE and AUCO; 0.55 ± 0.03 and 0.26 ± 0.04°C for PTCE and PTCO, respectively). In contrast, NTC was lower around ovulation than estrus (−0.28 ± 0.05 and −0.60 ± 0.06°C for NTCE and NTCO). Cows with greater estrous expression had greater AUC and PTC during estrus than around ovulation, but cows with lesser estrous expression had similar AUC and PTC. Increases in AUC [High THI (Temperature Humidity Index): High activity: 4.7 ± 0.5, Low activity: 1.5 ± 0.4; Low THI: High activity: 3.1 ± 0.2, Low activity: 1.4 ± 0.2 °C2] and PTC (High THI: High activity: 0.79 ± 0.08, Low activity: 0.36 ± 0.07; Low THI: High activity: 0.60 ± 0.04, Low activity: 0.47 ± 0.04°C) associated with estrous expression were found to be greater on days with higher THI. Alerts created using standard deviations from the mean were unable to detect estrus or ovulation with acceptable precision. Further research is required to determine how changes in RRT can be used successfully to predict estrus and ovulation.

Exploring the pattern of outdoor thermal comfort (OTC) in a tropical planning region of eastern India during summer

Assessment Outdoor Thermal Comfort (OTC) level in urban environment is necessary for effective climate sensitive planning. Particularly in Indian context it is important due to unplanned and haphazard urban expansion. This study aims to assess OTC using a micro level land use and land cover (LU/LC) classification system known as Local Climatic Zones (LCZs) on Sriniketan-Santiniketan Planning Area (SSPA) in Eastern India. Two thermal indices - Universal Thermal Climate Index (UTCI) and Temperature Humidity Index (THI) as well as several statistical tools (coefficient of variation, ANOVA and correlation) have been used to assess OTC. The result of the study showed that there were a variation of thermal comfort level over LCZs. Result of UTCI and THI recorded that highest maximum UTCI and THI were found over LCZ3, LCZ6 and LCZ9 that largely dominated by built up. On the other hand, relatively low UTCI and THI were recorded over natural land covers such as forest cover, water bodies. In all the built up LCZs, thermal sensation of the respondents ranges from warm to very hot because of impervious surface cover. The result of the study can contribute a lot in understanding the thermal comfort of a sub-tropical planning region and it may also inspire planners and policy makers to integrate OTC into proposed planning strategies for the improvement of thermal ambiance.

Effect of season and SNPs of HSP90 and HSP70 genes on the biochemical traits in Indian sheep (Ovis aries) breeds

Heat shock proteins (HSPs) are evolutionary conserved family of proteins produced by living cells in response to various biological stresses, including heat shock. Heat stress affects the productivity of the livestock species, which causes severe economic losses to the animal keepers. The present study was undertaken to establish reference baseline values for thyroid (T3 and T4) and adrenal gland (cortisol) hormones in four indigenous sheep breeds (Chokla, Marwari, Magra and Madras Red). The effect of the seasons and genotypes of the HSP90 and HSP70 genes on the functions of the thyroid gland as well as cortisol levels were examined in plasma samples of these sheep breeds. A total of 80 plasma samples (10 animals per breed for the summer and winter season) were analyzed. The least square analysis revealed significant seasonal effect on Triiodothyronine (T3) and Thyroxine (T4). Significantly higher T3 and T4 levels were observed in the winter with a low temperature humidity index (THI) than in summer with high THI. Cortisol was non-significantly higher in the summer than in winter season. Overall, the influence of the breeds on these three parameters was non-significant. Genotypes of SNP1 (HSP90 gene) and SNP2 (HSP70 gene) had significant effect on T3 level. These SNP markers may be useful for identifying animals that are more adaptable to heat stress following a thorough association analysis over a large sample size.

Fertility traits of recipient cows raised in the Amazon biome

This study aimed to evaluate a correlation between environmental temperature-humidity index (THI), rectal temperature (RT) and plasmatic concentration of cortisol in pregnancy rates of recipient cows in the Amazon biome. Recipient cows (n = 235) were submitted to an estrus synchronization simplified P36 protocol for a Fixed-Time Embryo Transference (FTEF). Rectal temperature of recipient cows and ambient temperature, relative humidity (RH) and dry-bulb temperature ( °C) were recorded on day zero (D0), eight (D8) and 16 (D16) of the protocol. On D16, each recipient received an embryo after the confirmation of a corpus luteum. At this moment, a blood sample was collected and cortisol concentration was evaluated in the sample with radioimmunoassay. On D41 (D33 embryo), pregnancy diagnosis was assessed (PD). The yield rates of recipient cows and pregnancy after the protocol were 66.81% (151/226) and 35.76% (54/151), respectively. Cows that became pregnant presented lower means in RT, plasmatic cortisol and THI parameters (P < 0.05) in comparison to non-pregnant group. The percentage of pregnant cows at Day 41 was higher (P < 0.0001) for cows that had RT ≤ 39.1 °C in all the days analyzed (D0, D8 and D16). Likewise, cows that entered the chute area under a low THI (< 74) had better (P < 0.005) pregnancy rates when compared with cows that were at the chute under a higher THI. This was observed on the three days evaluated throughout the protocol. The correlation coefficient between cortisol, RT and THI was above 59%. In addition, cortisol was lower in the PG cows. In conclusion, THI, RT and cortisol level are directly related to pregnancy success. Furthermore, this study could validate the use of THI as an auxiliary tool to assess thermal comfort and stress, which may reflect in the pregnancy outcome of recipient cows in the Amazon biome.

Correlation Between Blood Parameters, Physiological and Liver Gene Expression Levels in Native Laying Hens Under Heat Stress

The heat stress plays an important role in feed efficiency, blood profile, rate metabolism. Growth performance, health and its influence economic loss of layin hens can be strongly affected by climate. The study to investigate the effect of the heat stress on blood parameters (White Blood Cells/WBC, lymphocytes, neutrofils, glucose, creatinine, creatinine kinase/CK), physiological status (rectal temperature/RT, heart rate/HR), and liver gene expression (Glutamate pyruvate transaminase/GPT, Glutamate oxaloacetate transaminase/GOT, Threonine dehydrogenase/TDH, heat shock protein 70/HSP70) in laying hens. Two hundred native laying hens were randomly assigned to 10 groups of temperature humidity Index (THI), with 20 animals per group. They were kept in environmental condition with temperature humidity index (THI) ranging from 65.50 to 85.72 in temperature humidity. Blood plasma samples were used to determine the concentration of blood biochemical parameters, using a commercial kit by an automatic biochemical analyser. Liver gene expression levels were analyzed by Real-time PCR. The results showed that their RT, HR, WBC, neutrophilis, creatinine, CK, liver gene expression levels were increased in high THI compared to at low THI. In contrast, glucose and lymphocytes levels was decreased in high THI. In addition, HR, RT, WBC, neutrophilis, creatinine, CK, liver gene expression were positively correlated with THI. On the other hand, negatively correlated with THI were showed by glucose and lymphocite. As conclusion, based on these results, it can be concluded that all parameters in this study are closely associated with heat stress. These parameters can be consolidated to heat stress biomarkers in native laying hens.

EFFECTS OF CLIMATE CHANGE ON MILK YIELD AND MILK COMPOSITION IN THAI CROSSBRED HOLSTEIN COWS

The purpose of this research was to study effects of climate changes on milk yield and milk composition of Holstein crossbred . This study uses data recording total milk production per farm each day and milk composition (from 2013–2017): fat percentage (% Fat), protein percentage (% Pro), solid not fat percentage (% SNF) and total solid percentage (% TS) from 79 farmers in Mahasarakham Province, Thailand. The temperature and humidity data were obtained from records of meteorological center. Using temperature and relative humidity for calculate temperature humidity index (THI). The effects of THI on milk yield and milk composition were assessed by procedure REG using SAS. The study indicated that, the weather was hot and humid. The temperature ranged from 20.88 – 33.01 ° C. and average humidity was 72.59%. The highest THI (82.07) was in May. The relationship between THI and milk yield was negatively related. The slope value was -0.099, it meaning that when the THI value increased by 1 unit the milk yield decreased by 0.099 kg / cow / day. The THI group for effect of THI on milk yield and milk composition was set 4 groups (THI 1 = THI ≤70, THI 2 = 74 ≤THI 78). The highest THI effect on low milk yield. In contrast, low THI (THI 1 and THI 2) effect on high milk yields. The climate change, temperature and humidity increase effects on milk production of dairy cows to decrease.

PSXI-37 Differences in thermoregulation ability and genetic parameters of skin traits in Angus, Brahman and their Crossbreds

Abstract Thermoregulation is important for beef cattle but tends to be negatively correlated with production traits. The objective of this study was to determine the variation in core body temperature and to estimate genetic parameters of skin traits in Angus, Brahman, and different levels of crossbred heifers (n = 337) reared in hot and humid conditions. Core body temperature was recorded as vaginal temperature every 15 minutes for 5 consecutive days. Dry bulb temperature and relative humidity in the pasture were also measured every 15 min and used to calculate a temperature-humidity index (THI). Five mm skin biopsies were collected from the right side of sixth thoracic bone of each heifer. Cross-sections of biopsy samples with a thickness of 7 µm were stained with Hematoxilin–Eosin technique. The number and area of sweat and sebaceous glands, and the thickness of dermis and epidermis were determined using the ImageJ program. Data were analysed using PROC MIXED in SAS 9.4 with a model including the effect of breed, year, and their interaction. Genetic parameters were estimated using WOMBAT. Average core body temperature of Angus, 25%, 37.5%, 50%,75% and 100% Brahman were 39.50±0.05, 39.30±0.04, 39.15±0.05, 39.2±0.0, 39.03±0.05, 39.04±0.05, respectively. Brahman heifers had lower core body temperature compared to Angus heifers (P = 0.0006). Heifers with smaller and more numerous sweat glands had higher (P &amp;lt; 0.01) and more variable core body temperature (P &amp;lt; 0.0001). Heritability of core body temperature under high and low THI was 0.44±0.006 and 0.61±0.003, respectively. Dermis and epidermis thickness had the lowest heritability (0.231±0.002) and the highest heritability (0.75±0.007), respectively. Heritabilities for the number of sweat glands and total sweat gland area were 0.375±0.02 and 0.432±0.006, respectively. In conclusion, thermoregulation was highly correlated with breed composition, number of sweat glands and the average size of sweat glands.