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- ItemEffects of increasing air temperature on skin and respiration heat loss from dairy cows at different relative humidity and air velocity levels(Savoy, Ill. : ADSA, 2022) Zhou, M.; Huynh, T.T.T.; Groot Koerkamp, P.W.G.; van Dixhoorn, I.D.E.; Amon, T.; Aarnink, A.J.A.The focus of this study was to identify the effects of increasing ambient temperature (T) at different relative humidity (RH) and air velocity (AV) levels on heat loss from the skin surface and through respiration of dairy cows. Twenty Holstein dairy cows with an average parity of 2.0 ± 0.7 and body weight of 687 ± 46 kg participated in the study. Two climate-controlled respiration chambers were used. The experimental indoor climate was programmed to follow a diurnal pattern with ambient T at night being 9°C lower than during the day. Night ambient T was gradually increased from 7 to 21°C and day ambient T was increased from 16 to 30°C within an 8-d period, both with an incremental change of 2°C per day. A diurnal pattern for RH was created as well, with low values during the day and high values during the night (low: RH_l = 30-50%; medium: RH_m = 45-70%; and high: RH_h = 60-90%). The effects of AV were studied during daytime at 3 levels (no fan: AV_l = 0.1 m/s; fan at medium speed: AV_m = 1.0 m/s; and fan at high speed: AV_h = 1.5 m/s). The AV_m and AV_h were combined only with RH_m. In total, there were 5 treatments with 4 replicates (cows) for each. Effects of short and long exposure time to warm condition were evaluated by collecting data 2 times a day, in the morning (short: 1-h exposure time) and afternoon (long: 8-h exposure time). The cows were allowed to adapt to the experimental conditions during 3 d before the main 8-d experimental period. The cows had free access to feed and water. Sensible heat loss (SHL) and latent heat loss (LHL) from the skin surface were measured using a ventilated skin box placed on the belly of the cow. These heat losses from respiration were measured with a face mask covering the cow's nose and mouth. The results showed that skin SHL decreased with increasing ambient T and the decreasing rate was not affected by RH or AV. The average skin SHL, however, was higher under medium and high AV levels, whereas it was similar under different RH levels. The skin LHL increased with increasing ambient T. There was no effect of RH on the increasing rate of LHL with ambient T. A larger increasing rate of skin LHL with ambient T was observed at high AV level compared with the other levels. Both RH and AV had no significant effects on respiration SHL or LHL. The cows lost more skin sensible heat and total respiration heat under long exposure than short exposure. When ambient T was below 20°C the total LHL (skin + respiration) represented approx. 50% of total heat loss, whereas above 28°C the LHL accounted for more than 70% of the total heat loss. Respiration heat loss increased by 34 and 24% under short and long exposures when ambient T rose from 16 to 32°C.
- ItemThe physiological and productivity effects of heat stress in cattle : a review(Warsaw : De Gruyter Open, 2019) Herbut, Piotr; Angrecka, Sabina; Godyń, Dorota; Hoffmann, GundulaA trend of global warming has been observed over the last few years and it has often been dis-cussed whether there is an effect on livestock. numerous studies have been published about heat stress in cattle and its influence on the physiology and productivity of animals. Preventing the negative effects of heat stress on cattle is essential to ensure animal welfare, health and produc-tivity. Monitoring and analysis of physiological parameters lead to a better understanding of the adaptation processes. This can help to determine the risk of climate change and its effects on performance characteristics, e.g. milk yield and reproduction. This, in turn, makes it possible to develop effective measures to mitigate the impact of heat load on animals. The aim of this article is to provide an overview of the current literature. studies especially about the physiological and productive changes due to heat stress in cattle have been summarised in this review. The direction of future research into the aspect of heat stress in cattle is also indicated
- ItemEffect of two cooling frequencies on respiration rate in lactating dairy cows under hot and humid climate conditions(Warsaw : De Gruyter Open, 2019) Pinto, Severino; Hoffmann, Gundula; Ammon, Christian; Heuwieser, Wolfgang; Levit, Harel; Halachmi, Ilan; Amon, ThomasThe aim of this study was to evaluate the effects of evaporative cooling at two different frequen-cies per day on the respiration rate (rr) of lactating dairy cows, considering cow-related factors. twenty multiparous israeli holstein dairy cows housed in a naturally ventilated cowshed were di-vided randomly into two treatment groups. the cows of both groups were exposed to 3 or 8 cooling sessions per day (3xcool vs. 8xcool, respectively). the rr was observed hourly, with a maximum of 12 measurements per day. Body posture (standing vs. lying) was simultaneously documented. milk yield was recorded daily. coat color was determined from a digital photograph. the rr of standing and lying cows was lower in the 8xcool group (60.2 and 51.6 breaths per min (bpm), re-spectively) than in the 3xcool group (73.1 and 65.6 bpm, respectively). For each increment of five kilograms of milk produced, rr increased by one bpm, and the rr of cows in early days in milk (dim) was 12.3 bpm higher than that of cows in late dim. in conclusion, eight cooling sessions per day instead of three lead to a rr abatement in heat-stressed cows under hot conditions, and cow-related factors directly impact the rr during heat stress assessment
- ItemDeadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°C of Global Warming(Hoboken, NJ : Wiley, 2021) Saeed, Fahad; Schleussner, Carl‐Friedrich; Ashfaq, MoetasimSouth Asia (SA) is one of those hotspots where earliest exposure to deadly wet-bulb temperatures (Tw >35°C) is projected in warmer future climates. Here we find that even today parts of SA experience the upper limits of labor productivity (Tw >32°C) or human survivability (Tw >35°C), indicating that previous estimates for future exposure to Tw-based extremes may be conservative. Our results show that at 2°C global warming above pre-industrial levels, the per person exposure approximately increases by 2.2 (2.7) folds for unsafe labor (lethal) threshold compared to the 2006–2015 reference period. Limiting warming to 1.5°C would avoid about half that impact. The population growth under the middle-of-the-road socioeconomic pathway could further increase these exposures by a factor of ∼2 by the mid-century. These results indicate an imminent need for adaptation measures, while highlighting the importance of stringent Paris-compatible mitigation actions for limiting future emergence of such conditions in SA.
- ItemA systematic review of non-productivity-related animal-based indicators of heat stress resilience in dairy cattle(San Francisco, California, US : PLOS, 2018-11-1) Galán, Elena; Llonch, Pol; Villagrá, Arantxa; Levit, Harel; Pinto, Severino; del Prado, AgustínIntroduction Projected temperature rise in the upcoming years due to climate change has increased interest in studying the effects of heat stress in dairy cows. Environmental indices are commonly used for detecting heat stress, but have been used mainly in studies focused on the productivity-related effects of heat stress. The welfare approach involves identifying physiological and behavioural measurements so as to start heat stress mitigation protocols before the appearance of impending severe health or production issues. Therefore, there is growing interest in studying the effects of heat stress on welfare. This systematic review seeks to summarise the animal-based responses to heat stress (physiological and behavioural, excluding productivity) that have been used in scientific literature. Methods Using systematic review guidelines set by PRISMA, research articles were identified, screened and summarised based on inclusion criteria for physiology and behaviour, excluding productivity, for animal-based resilience indicators. 129 published articles were reviewed to determine which animal-based indicators for heat stress were most frequently used in dairy cows. Results The articles considered report at least 212 different animal-based indicators that can be aggregated into body temperature, feeding, physiological response, resting, drinking, grazing and pasture-related behaviour, reactions to heat management and others. The most common physiological animal-based indicators are rectal temperature, respiration rate and dry matter intake, while the most common behavioural indicators are time spent lying, standing and feeding. Conclusion Although body temperature and respiration rate are the animal-based indicators most frequently used to assess heat stress in dairy cattle, when choosing an animal-based indicator for detecting heat stress using scientific literature to establish thresholds, characteristics that influence the scale of the response and the definition of heat stress must be taken into account, e.g. breed, lactation stage, milk yield, system type, climate region, bedding type, diet and cooling management strategies. © 2018 Galan∗E.∗Elena et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- ItemEnhanced economic connectivity to foster heat stress-related losses(Washington, DC : American Association for the Advancement of Science, 2016) Wenz, Leonie; Levermann, AndersAssessing global impacts of unexpected meteorological events in an increasingly connected world economy is important for estimating the costs of climate change. We show that since the beginning of the 21st century, the structural evolution of the global supply network has been such as to foster an increase of climate-related production losses. We compute first- and higher-order losses from heat stress–induced reductions in productivity under changing economic and climatic conditions between 1991 and 2011. Since 2001, the economic connectivity has augmented in such a way as to facilitate the cascading of production loss. The influence of this structural change has dominated over the effect of the comparably weak climate warming during this decade. Thus, particularly under future warming, the intensification of international trade has the potential to amplify climate losses if no adaptation measures are taken.
- ItemThe role of city size and urban form in the surface urban heat island(London : Nature Publishing Group, 2017) Zhou, B.; Rybski, D.; Kropp, J.P.Urban climate is determined by a variety of factors, whose knowledge can help to attenuate heat stress in the context of ongoing urbanization and climate change. We study the influence of city size and urban form on the Urban Heat Island (UHI) phenomenon in Europe and find a complex interplay between UHI intensity and city size, fractality, and anisometry. Due to correlations among these urban factors, interactions in the multi-linear regression need to be taken into account. We find that among the largest 5,000 cities, the UHI intensity increases with the logarithm of the city size and with the fractal dimension, but decreases with the logarithm of the anisometry. Typically, the size has the strongest influence, followed by the compactness, and the smallest is the influence of the degree to which the cities stretch. Accordingly, from the point of view of UHI alleviation, small, disperse, and stretched cities are preferable. However, such recommendations need to be balanced against e.g. positive agglomeration effects of large cities. Therefore, trade-offs must be made regarding local and global aims.