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DDC: 630 × Subject: Heat stress ×

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    The effects of heat stress on the behaviour of dairy cows – a review
    (Warsaw : De Gruyter Open, 2021-5-8) Herbut, Piotr; Hoffmann, Gundula; Angrecka, Sabina; Godyń, Dorota; Vieira, Frederico Márcio Corrêa; Adamczyk, Krzysztof; Kupczyński, Robert
    Heat stress in livestock is a function of macro- A nd microclimatic factors, their duration and intensity, the environments where they occur and the biological characteristics of the animal. Due to intense metabolic processes, high-producing dairy cows are highly vulnerable to the effects of heat stress. Disturbances in their thermoregulatory capability are reflected by behavioural, physiological and production changes. Expression of thermoregulatory behaviour such as reduction of activity and feed intake, searching for cooler places or disturbances in reproductive behaviours may be very important indicators of animal welfare. Especially maintenance of standing or lying position in dairy cattle may be a valuable marker of the negative environmental impact. Highly mechanized farms with large numbers of animals have the informatic system that can detect alterations automatically, while small family farms cannot afford this type of equipment. Therefore, observing and analysing behavioural changes to achieve a greater understanding of heat stress issue may be a key factor for developing the effective strategies to minimize the effects of heat stress in cattle. The aim of this review is to present the state of knowledge, over the last years, regarding behavioural changes in dairy cows (Bos taurus) exposed to heat stress conditions and discuss some herd management strategies providing mitigation of the overheat consequences.
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    Optimization of short-term hot-water treatment of apples for fruit salad production by non-invasive chlorophyll-fluorescence imaging
    (Basel : MDPI AG, 2020) Herppich, Werner B.; Maggioni, Marco; Huyskens-Keil, Susanne; Kabelitz, Tina; Hassenberg, Karin
    For fresh ]cut salad production, hot-water treatment (HWT) needs optimization in terms of temperature and duration to guarantee a gentle and non-stressing processing to fully retain product quality besides an effective sanitation. One major initial target of heat treatment is photosynthesis, making it a suitable and sensitive marker for HWT effects. Chlorophyll fluorescence imaging (CFI) is a rapid and non ]invasive tool to evaluate respective plant responses. Following practical applications in fruit salad production, apples of colored and of green ]ripe cultivars ( eBraeburn f, eFuji f, eGreenstar f, eGranny Smith f), obtained from a local fruit salad producer, were hot ]water treated from 44 to 70 °C for 30 to 300 s. One day after HWT and after 7 days of storage at 4 °C, CFI and remission spectroscopy were applied to evaluating temperature effects on photosynthetic activity, on contents of fruit pigments (chlorophylls, anthocyanins), and on various relevant quality parameters of intact apples. In eBraeburn f apples, short ]term HWT at °C for 30 to 120 s avoided any heat injuries and quality losses. The samples of the other three cultivars turned out to be less sensitive and may be short-term heat-treated at temperatures of up to 60 °C for the same time. CFI proved to be a rapid, sensitive, and effective tool for process optimization of apples, closely reflecting the cultivar-or batch-specificity of heat effects on produce photosynthesis. © 2020 by the authors.