Evaluation of Phule Amrutkal mobile application for estimation of Temperature Humidity Index (THI) in cattle

Introduction

Climate change, predicted to raise global temperatures by about 0.2 °C per decade, poses a major challenge to livestock production worldwide. Rising temperature, humidity, and solar radiation directly affect animal growth, productivity, and welfare, with heat stress being the most critical factor in tropical and subtropical regions. When exposed to excessive heat, cattle struggle to maintain thermal balance, leading to elevated body temperature, increased respiration and pulse rate, reduced feed intake, and higher water consumption.

Once environmental temperatures exceed the upper critical limits (24-26 °C for crossbred/exotic cattle, 33 °C for Zebu cattle, and 36 °C for Water buffalo), their evaporative cooling mechanisms fail, causing hyperthermia. The combined effect of air temperature and humidity on thermal stress is expressed as the Temperature-Humidity Index (THI). THI values below 72 indicate no stress, 73-77 mild, 78-89 moderate, and ≥ 90 severe stress. Elevated humidity further reduces heat dissipation through evaporation, aggravating thermal load. Heat stress impairs immunity, lowers feed intake and milk yield, and disrupts reproductive efficiency, with crossbred and Bos taurus cattle being more vulnerable than indigenous Bos indicus breeds, which have lower metabolic rates and better heat tolerance but lower productivity. THI is widely used to assess livestock thermal comfort (Yousef, 1985; Thom, 1959; Mader, 2006; Berman, 2016) [36,34,30,9] . Understanding physiological, haematological, and biochemical responses such as changes in rectal temperature, respiration, sweating, blood flow, hormones, and metabolites helps explain heat adaptation mechanisms and their impacts on productivity (Silanikove et al., 1997; Ganaie et al., 2013) [32, 23] . To address rising heat stress risks, the Phule Amrutkal mobile application has been developed as a climate-smart advisory tool. Using open-source weather data and THI models (National Research Council [NRC], 1971; Mader, 2006; Berman, 2016) [30,9,31,30] , it estimates THI in real time and issues automatic livestock management advisories on feeding, watering, housing, and health. With a simple, multilingual interface and color-coded stress categories (Normal, Alert, Danger, Emergency), it enables farmers to take timely preventive measures. The app's integration of meteorological data and threshold-based advisories promotes climate-resilient livestock farming by safeguarding cattle health and productivity. In this study, ambient temperature and relative humidity data from the India Meteorological Department observatory were used to compute THI (NRC 1971; Mader 2006; Berman 2016) [31,30,9] across summer, rainy, and winter seasons. These values validated the THI outputs from the Phule Amrutkal app and were compared with real-time sensor data from the experimental farm.

Materials and Methods

The present study entitled "Evaluation of Phule Amrutkal mobile application for estimation of Temperature-Humidity Index (THI) in Cattle" was carried out during 2024-2025 at the Indigenous Cattle Research cum Training Centre (ICRTC), Division of Animal Husbandry and Dairy Science, College of Agriculture, Pune, under Mahatma Phule Krishi Vidyapeeth (MPKV), Rahuri. The site is located at 18.5447° N latitude and 73.8496° E longitude, at an elevation of 530-570 m above sea level. The region experiences temperatures ranging from 5 °C to 46 °C (mean 24.3 °C), relative humidity averaging 60-63% (up to 81-83% in monsoon), and annual rainfall averaging 722 mm, mostly during June-September. Thirty clinically healthy cattle (five animals from each of six breeds, including indigenous and crossbred types) of similar age and managed under uniform housing, feeding, and watering conditions were selected. The Phule Amrutkal mobile application uses open-source meteorological data to provide temperature and relative humidity, computing THI to assess livestock heat stress and offering weather-based advisories. Data was collected during morning (8 AM) and afternoon (2 PM) in summer, rainy, and winter seasons. THI Estimation: THI was calculated using model National Research Council (NRC, 1971) [31]: THI=(1.8×T+32)-[(0.55-0.0055×RH/100)×(1.8×T-26)]

Physiological Parameters

The physiological parameters respiration rate, rectal temperature, pulse rate, skin temperature and thermographic image was recorded in every week of interval in adhering to standard clinical procedure.

Results and Discussion

The above In Indigenous cattle, the morning respiration rate was largely independent of THI (r=-0.17), whereas the afternoon respiration rate showed a stronger positive correlation with THI (r=0.46). This indicates that Indigenous cattle are less responsive to morning fluctuations but exhibit a more pronounced response during afternoon heat stress. In crossbred cattle, both morning (r=0.33) and particularly afternoon respiration rates (r=0.82) demonstrated significant positive correlations with THI, thereby highlighting their higher susceptibility to thermal stress throughout the year. Indigenous cattle displayed a negative correlation with THI in the morning, which suggests effective thermoregulatory adaptation during the early hours when ambient heat stress is relatively low. However, the moderate positive correlation observed in the afternoon indicates that these animals become more susceptible once the thermal load accumulates. In contrast, crossbred cattle exhibited a consistent positive correlation with THI, which was more pronounced during the afternoon period. The strong correlation observed in the afternoon (r=0.82) emphasizes their heightened vulnerability to heat stress. During the summer season, the peak in afternoon respiration rate indicates that heat stress is most severe during this period, particularly in crossbred cattle. In the monsoon season, although THI levels moderate slightly, the persistently high humidity continues to impose stress on crossbreds, while Indigenous breeds demonstrate better adaptability with relatively stable respiration rates. In the post-monsoon and winter seasons, afternoon respiration rates increase again, particularly in February, suggesting the influence of seasonal transition stress. In the morning period, Indigenous cattle exhibited an almost negligible association with THI (r=0.15), whereas crossbred cattle showed a moderate positive correlation (r=0.57), reflecting their greater thermal sensitivity during the early hours of the day. In the afternoon period, both Indigenous cattle (r=0.14) and crossbred cattle (r=0.28) demonstrated weak positive correlations, suggesting that rectal temperature in the afternoon is less directly governed by THI, likely due to compensatory physiological adjustments that moderate internal body temperature under elevated thermal load.

In the morning, rectal temperature exhibited stronger alignment with THI, particularly in crossbred cattle. This finding suggests that morning rectal temperature reflects the accumulation of overnight heat load and serves as a reliable early indicator of thermal stress. In the afternoon, the correlations weakened for both Indigenous and crossbred cattle, highlighting the influence of adaptive physiological responses such as increased respiration rate and sweating, which help to maintain rectal temperature within a narrow range despite elevated THI levels.

During the summer season, both crossbred and indigenous cattle exhibited a gradual rise in rectal temperature, with morning values showing a relatively higher sensitivity to increasing THI levels. In the monsoon season, the combined effect of elevated humidity and moderate ambient temperatures contributed to maintaining rectal temperatures within a narrow range, with only weak correlations observed between THI and afternoon rectal temperature. In the postmonsoon period, rectal temperature patterns remained largely stable, indicating a possible acclimatization of cattle to the prevailing moderate THI conditions. During winter, morning rectal temperature tended to decline, particularly in February, while afternoon rectal temperature showed a slight increase, reflecting the influence of diurnal thermal variations even under comparatively mild THI conditions. Crossbred cattle were consistently more responsive to changes in THI during the morning (r=0.57), whereas Indigenous cattle exhibited minimal fluctuations, indicating their higher adaptive thermotolerance. Morning rectal temperature in crossbred cattle serves as a reliable indicator of thermal load and is useful for identifying animals that are more vulnerable to heat stress. In contrast, afternoon rectal temperature alone is not sufficient for accurate heat stress assessment, as compensatory physiological mechanisms tend to dampen its correlation with THI. Under such conditions, respiration rate (RR) emerges as a more sensitive and reliable indicator during the afternoon period.

Similar finding was also given by Bhan et al., (2013) [12] found that RT in Karan Fries cattle increased by ~0. [2,3] demonstrated that crossbred cows in tropical climates recorded significantly higher RT in summer (THI ~80.9) compared to winter (THI ~65.7). Reported that RT in crossbred cows increased significantly with rises in air temperature, humidity, and THI, emphasizing their greater vulnerability to thermal stress compared to indigenous breeds. The temperature-humidity index (THI) of the same and the previous day on morning (a.m.) and afternoon (p.m.) rectal temperatures (RT). Physiological responses showed a diurnal pattern, being lower in the mornings than the afternoons. The objective of this study was to evaluate relationships between measurements of Temperature-Humidity Index (THI) and rectal temperatures in lactating cows exposed to Heat Stress (HS). It showed increase in rectal temperature with increasing THI. In Indigenous cattle, the morning pulse rate (PR) showed minimal association with THI (r=0.05), while the afternoon correlation was slightly higher (r=0.16). In crossbred cattle, the morning PR exhibited a moderate positive correlation (r=0.44), indicating higher thermal sensitivity, whereas the afternoon correlation remained weak (r=0.23). Morning PR in Indigenous cattle showed weak dependency on THI, indicating greater thermotolerance and adaptive stability. In contrast, crossbred cattle exhibited a moderate positive correlation (r=0.44), suggesting that morning PR serves as a reliable stress indicator in this group. During the afternoon, both breeds showed weaker correlations with THI, as adaptive mechanisms such as increased respiration and peripheral blood flow helped modulate the cardiovascular response. Nevertheless, afternoon PR values remained elevated, particularly during summer and late winter, reflecting the accumulation of diurnal stress. During summer, afternoon Pulse Rate (PR) was highest, particularly in crossbred cattle, highlighting the peak of heat stress, while Indigenous cattle remained relatively stable but still exhibited mild increases. In the monsoon season, despite moderate THI values, high humidity contributed to elevated PR, with crossbreds showing a distinct peak in September. In the post-monsoon period, PR values stabilized, with Indigenous cattle displaying comparatively less variation. During winter, afternoon PR increased again, particularly in February, suggesting that bright sunny days induced transient thermal stress despite lower THI levels. Indigenous cattle maintained relatively stable pulse rates (PR) across varying THI ranges, reflecting higher adaptability and thermotolerance. In contrast, crossbred cattle consistently exhibited higher PR values with stronger correlations to THI, indicating a greater cardiovascular response to heat stress and comparatively lower thermal resilience. Morning Pulse Rate (PR) in crossbred cattle can serve as a sensitive physiological marker of thermal stress. Although afternoon PR is less reliable as a standalone indicator due to adaptive regulatory mechanisms, its assessment in combination with respiration rate (RR) offers valuable insight into the overall stress load. Similar trend was observed by Joshi et al., (1982) moderate increases in pulse rate (PR) in Murrah buffalo heifers exposed to hot arid and humid ambiences, establishing PR as a sensitive heat stress indicator. Reported a positive correlation between THI and heart rate in Holstein-Friesian cows under Mediterranean conditions, with PR increasing by 6 beats/min as THI rose from 68 to 78, supporting the positive THI-PR association in crossbreds. Found that PR in Karan Fries cattle rose significantly during hot-humid and summer seasons compared to spring, with strong positive correlation with THI, confirming your finding of higher PR in crossbreds under summer and monsoon stress. Demonstrated a highly significant positive correlation between THI and PR in both buffalo (r=0.921) and crossbred calves (r=0.925) under Kerala's hot-humid climate, consistent with your results showing moderate positive correlations for crossbreds. Reported that crossbred cows housed with cooling (foggers + fans) exhibited significantly lower PR compared to control cows under high THI, highlighting the cardiovascular stress of crossbreds during summer. Aggarwal et al., (2019) [5] observed significant seasonal variations in PR across Sahiwal, Tharparkar, Gir, and Karan Fries breeds, with crossbreds showing higher PR in summer compared to indigenous breeds, validating breed-based differences in cardiovascular sensitivity. Found that PR increased markedly during summer compared to winter in both Sahiwal and Karan Fries, with crossbreds showing a stronger rise, supporting your seasonal trend of elevated afternoon PR. documented that exposure of Tharparkar (indigenous) and Karan Fries (crossbreds) to THI 91 increased PR significantly more in Karan Fries (+14 beats/min) than Tharparkar (+13 beats/min), affirming crossbred vulnerability. Determined THI thresholds for PR in goats, with values between 71-79 depending on breed, showing that PR responds early to thermal stress and confirming its role as a reliable physiological marker, especially in more sensitive breeds. Reported that high summer THI values in Bulgarian dairy goats significantly elevated PR (p<0.001), supporting the general principle that PR is a strong indicator of heat stress across livestock species. Murrah buffaloes and Karan fries cattle and in their studies they observed that average maximum temperature was (40.8 °C) at 2 pm and THI at that time was 85, the physiological responses like RT, RR, PR were increased significantly (p<0.01) at 2 pm as compared to the respective values at 2 am. They reported that different indices have been used to measure the impact of heat stress but the most widely used indicator is THI. [12] seasonal variability in Karan Fries cattle and found that physiological parameters, including skin temperature, increased significantly during summer and hot-humid seasons compared to spring. They also reported strong positive correlations between Temperature Humidity Index (THI) and surface temperatures, confirming that peripheral indicators such as muzzle or skin temperature reflect heat load. found that cooling interventions (foggers and fans) significantly reduced physiological responses such as respiration rate, rectal temperature, and pulse rate in crossbred cows during high THI, further indicating that crossbreds exhibit higher peripheral heat stress markers like muzzle temperature unless managed. Reported strong correlations between surface/ muzzle temperatures and THI, highlighting the reliability of peripheral temperatures as non-invasive heat stress indicators. showed that indigenous Tharparkar cattle recorded smaller rises in surface body temperature at THI 91 compared to crossbred Karan Fries, who exhibited sharper increases. Indigenous breeds show stable MT, while crossbreds are more sensitive. highlighted seasonal effects on peripheral temperatures and blood flow in multiple indigenous (Sahiwal, Tharparkar, Gir) and crossbred (Karan Fries) breeds. Crossbreds showed significantly higher thermal load indicators during summer, confirming the breed-based differences in muzzle/surface temperature. Studied on goat in high summer THI (32-33 °C inside barns) significantly elevated peripheral body temperatures (p<0.001). Their findings support the broader principle that muzzle and skin temperatures rise proportionally with THI under tropical heat stress. [12] reported that Karan Fries cattle. Rise in ET with higher [5] noted that skin temperature was significantly higher in crossbreds (Karan Fries) compared to indigenous breeds (Sahiwal, Gir, Tharparkar) during summer and post-monsoon, confirming breed differences in thermotolerance. Skin temperature, increases with increasing THI in dairy cows, especially in high-yielding or crossbred animals. Reported that summer THI values (32-33 °C indoors) significantly elevated peripheral skin/body temperature in dairy goats (p<0.001), confirming the principle that ST rises disproportionately under high THI and reflects seasonal stress. Reported that Skin temperature emerged as the most sensitive indicator of environmental stress, with THIadj (Mader et al., 2006) [30] showing the strongest correlations.

Effect of THI on

Effect

Effect of THI on ear temperature (℃) of cattle in morning and afternoon (Ideal range of Ear temp. in cattle 35-38°)

Effect of THI

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