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End date: 2021 × Subject: heat stress ×

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Now showing 1 - 4 of 4
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    The physiological and productivity effects of heat stress in cattle : a review
    (Warsaw : De Gruyter Open, 2019) Herbut, Piotr; Angrecka, Sabina; GodyƄ, Dorota; Hoffmann, Gundula
    A 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
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    Effect 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, Thomas
    The 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
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    Enhanced economic connectivity to foster heat stress-related losses
    (Washington, DC : American Association for the Advancement of Science, 2016) Wenz, Leonie; Levermann, Anders
    Assessing 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.
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    The 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.