Lack of vegetation exacerbates exposure to dangerous heat in dense settlements in a tropical African city

Both climate change and rapid urbanization accelerate exposure to heat in the city of Kampala, Uganda. From a network of low-cost temperature and humidity sensors, operational in 2018-2019, we derive the daily mean, minimum and maximum Humidex in order to quantify and explain intra-urban heat stress variation. This temperature-humidity index is shown to be heterogeneously distributed over the city, with a daily mean intra-urban Humidex Index deviation of 1.2°C on average. The largest difference between the coolest and the warmest station occurs between 16:00 and 17:00 local time. Averaged over the whole observation period, this daily maximum difference is 6.4°C between the warmest and coolest stations, and reaches 14.5°C on the most extreme day. This heat stress heterogeneity also translates to the occurrence of extreme heat, shown in other parts of the world to put local populations at risk of great discomfort or health danger. One station in a dense settlement reports a daily maximum Humidex Index of >40°C in 68% of the observation days, a level which was never reached at the nearby campus of the Makerere University, and only a few times at the city outskirts. Large intra-urban heat stress differences are explained by satellite earth observation products. Normalized Difference Vegetation Index (NDVI) has the highest (75%) power to predict the intra-urban variations in daily mean heat stress, but strong collinearity is found with other variables like impervious surface fraction and population density. Our results have implications for urban planning on the one hand, highlighting the importance of urban greening, and risk management on the other hand, recommending the use of a temperature-humidity index and accounting for large intra-urban heat stress variations and heat-prone districts in urban heat action plans for tropical humid cities.

Efek Temperature Humidity Index terhadap Konsumsi Air Minum dan Performans Ayam Kampung Super dengan Pemberian Enkapsulasi Fitobiotik Minyak Buah Merah

Ayam kampung super merupakan salah satu ayam kampung yang ditingkatkan performannya dengan perkawinan silang. Akan tetapi, perkawinan silang tidak serta merta memperbaiki performan. Ada beberapa hal lain yang mempengaruhi performan yaitu lingkungan dan feed additive. Oleh karena itu, tujuan dari penelitian ini adalah untuk mengetahui pengaruh Temperature Humidity Index dan pemberian enkapsulasi fitobiotik minyak buah merah terhadap konsumsi air minum dan performans ayam kampung super. Materi yang digunakan adalah alat ekstraksi, alat dan bahan enkapsulasi, buah merah, kandang individu dan ayam kampung super serta pakan starter. Metode penelitian yang digunakan yaitu Rancangan Acak Lengkap 5 perlakuan dan 4 ulangan dengan uji lanjut Duncan Multiple Range Test. Pemeliharaan dilakukan selama 56 hari dengan Temperature Humidity Index yaitu 24,44 - 35,21 oC. Hasil penelitian menunjukan bahwa penambahan enkapsulasi buah merah tidak berpengaruh terhadap konsumsi air minum (P>0,05), konsumsi pakan (P>0,05), feed conversion ratio (P>0,05) dan berpengaruh nyata terhadap pertambahan bobot badan (P<0,05). Berdasarkan hasil penelitian dapat disimpulkan bahwa kondisi lingkungan dilokasi penelitian (Papua) relatif ekstrim dilihat dari selisih THI. Selain itu, berdasarkan uji lanjut bahwa penambahan enkapsulasi fitobiotik minyak buah merah terhadap penambahan bobot badan menghasilkan perlakuan terbaik pada penambahan 2,5% enkapsulasi minyak buah merah.

Comparative Analysis of the Cooling Efficiency in Tropical Climate of Three Alternative Materials for Evaporative Cooling Pads

A comparison between commercial cellulose evaporative cooling pad and pads manufactured with three alternative materials was made for environmental conditions typical of tropical countries. Wind tunnel tests were carried out to compute the convective heat and mass transfer coefficients and to measure the pressure drop across each pad, obtaining expressions that can be used as reference for future simulations. Using a mathematical model, a detailed analysis of the efficiency, Temperature–Humidity Index, temperature drop and relative humidity through the pads was performed in terms of different operative and constructive conditions, such as air velocities, dry-bulb temperatures, relative humidity and pad thickness. Significant differences between the pressure drop across the pads were found, which increases with the inlet air velocity and water flow. A weak relation between the analysed variables and the inlet air velocity was found, while a high correlation between the analysed variables, pad thickness and the external environmental conditions was established. Cooling efficiencies above 40% and a Temperature–Humidity Index below the mild zone of thermal stress were obtained for the alternative panels. Although the cellulose cooling pad showed the best behaviour in all aspects, the alternative pads can be used as substituted in specific applications to reduce the Temperature–Humidity Index inside agricultural facilities.

Effect of Temperature-Humidity-Index on Milk Performances of Local Born Holstein Dairy Cows Under Saharan Climate

The objective is to study the effect of heat stress on milk yield (MY) relative to milking records (n=18178) of native Holsteins (n=187), in the region of Ghardaia, according to periods of HS, using the temperature-humidity index (THI). With THI >72 during 07 months in the study area, which significantly (P<0.001) decrease the MY (-15.5% corresponding to 21.73 kg). Also, calving periods led to a significant drop (P < 0.001) in overall MY (7030.35 kg) of the order of (-14.6%), and over the lactation length (353.43 d), which explains 41% of the variations in MY. In addition, the non-significant effect (P=0.212) of the lactation range on the increase in MY, moreover, the lactation length shows a non-significant (P = 0.108) decrease (-4.68%) during heat stress (HS). Furthermore, the significant effect (P <0.001) of the interaction (Milking frequency × THI) on MY, when THI variates from < 74 to > 84, with regression of (-16.82% and -08.82%) of the MF (2X and 3X), respectively. Again, the NH cow is less sensitive to hyperthermia, so THI explains only 2% of the variation in MY levels. Thus, NH in arid regions have the ability to acclimatize to Saharan environmental conditions.

Relationship of the Temperature-Humidity Index (THI) with Ovarian Responses and Embryo Production in Superovulated Thai-Holstein Crossbreds under Tropical Climate Conditions

Heat stress strongly negatively affects reproductive traits in dairy cattle. The purpose of the present study was to investigate the effect of heat stress in superstimulated Thai-Holstein crossbreds under tropical climate conditions. Data included 75 records from 12 superovulated Thai-Holstein crossbreds between 2018 and 2020. Cows were superstimulated with conventional treatment. The mean temperature-humidity index (THI) was evaluated for three data collection periods: during the 9, 21 and 42-day periods before the insemination day to determine the period in which THI mostly affected superstimulation responses. The THI levels/thresholds were determined and interpreted together with the superovulatory response. A significantly negative correlation was obtained for the THI during the period 9 days before insemination. Negative effects on the number of large follicles and corpora lutea began at a THI of 72 and were apparently severe after a THI of 77, similar to the ovulation rate, fertilized ova and transferable embryos (p < 0.05). Meanwhile, more degenerated embryos were found with THI values (p < 0.05). The superovulatory response in Thai-Holstein crossbreds under tropical climate conditions is highly affected by heat stress starting at a THI of 72 and becomes more severe at a THI higher than 77.

Heat Stress Mitigation with Fogging System of Anatolian Water Buffaloes

This research was carried out to investigate the possibilities of removing the heat stress that may occur in Anatolian water buffaloes with a fogging system and to determine the cooling efficiency of the system. In this context, two 24-headed groups were formed among the water buffaloes that were considered to have the same genetic similarities, were born in the same period and have the same lactation number. One group was housed under controlled shelter conditions (Shelter-I), where the ambient temperature can be controlled, and the other group was housed in existing farmer-raising conditions (Shelter-II). The same feed rations were applied to both buffalo groups. The cooling efficiency of the fogging system established in Shelter-I was between 45.6% and 85.7% positive. Temperature-Humidity Index values changed between 19.9 and 23.1 in Shelter-I and 19.5 and 26.4 in Shelter-II according to the maximum average data. According to these values, the level of stress in Shelter-II has reached very serious levels and affected the milk yield of buffaloes negatively. The corrected 305-day lactation milk yields were calculated as 1965.4 kg in Shelter-I and 1757.1 kg in Shelter-II. The differences between all data obtained for Shelter-I and Shelter-II were found statistically significant.

Critical Temperature-Humidity Index Thresholds Based on Surface Temperature for Lactating Dairy Cows in a Temperate Climate

Detecting the early signs of heat stress is highly important in dairy farming. The surface temperature (ST) of cattle can reflect their thermal status and using such a measuring method can be efficient and non-invasive. However, few studies have reported the temperature-humidity index (THI) thresholds for ST. This study aimed to identify the critical THI thresholds for the ST of dairy cows and to evaluate the effects of the lactation stage and the lactation number. The study included 233 Holstein lactating cows from July 2020 to October 2020 in a temperate climate in China. There were 1556 records of the rectal temperature, and the maximum ST (STmax) and average ST (STave) of the head, eye, cheek, ear, neck, trunk, udder, foreleg, and hindleg were recorded. Air temperature and relative humidity were recorded to calculate the average THI. Physiological data were collected twice daily (08:00–12:00, 14:00–16:00). The critical THI thresholds were determined using the breakpoints of piecewise linear models. The significance of breakpoints was tested using the Davies test. A one-way ANOVA was used to test the effect of the lactation stage (0–60 DIM, 61–200 DIM, 201–300 DIM, DIM is days in milk) and the lactation number (1, 2, 3+) on the THI thresholds. The results showed that the rectal temperature was significantly positively correlated with all the ST variables (0.57 ≤ r ≤ 0.71, p < 0.01). The critical THI thresholds for STmax (mean of 76.1 THI, range of 73.6 to 77.9 THI) were significantly higher than those for STave (mean of 72.6 THI, range of 69.1 to 77.2 THI) (p < 0.01). The lactation stage only significantly affected the thresholds for STmax (p < 0.05), and the lactation number did not significantly influence the thresholds for both STmax and STave (p > 0.05). This study concluded that the STave was more appropriate to define thresholds than the STmax. The threshold for the STave of the cheek (69.1 THI) was the lowest among the thresholds, indicating that the STave of the cheek could be a prior ST variable to determine critical THI thresholds. Our findings demonstrated the potential of using ST variables to define critical THI thresholds.