The aim of this study was to assess the impact of heat stress in dairy cows on test-day records for production traits and somatic cell score (SCS) in the state of Lower Saxony, Germany. Three different production systems were defined: A production system characterized by intensive crop production (=indoor housing), a pasture based production system, and a maritime region. Heat stress was assessed by two temperature-humidity indices (THI) modelled as random regression coefficients in an analysis of variance: One (THI Bo ) was defined as an average of hourly THI, calculated from hourly recorded temperatures and humidities, the other (THI Ra ) was based on daily maximal temperature and daily minimal humidity. In all production systems, THI Bo =60 and THI Ra =70 were identified as general thresholds denoting a substantial decline in test-day milk yield. For daily fat and protein percentage, no universally valid thresholds were identified. In contrast for SCS, especially in the maritime region, heat stress as well as cold stress thresholds were found. Regression analysis was used to study the change in test day milk yield in response to THI of those THI ranges with an obvious decline in milk yield. Regression coefficients were −0.08 kg/THI Bo and −0.16 kg/THI Ra for the crop production system, −0.17 kg/THI Bo and −0.23 kg/THI Ra for the pasture based system, and −0.26 kg/THI Bo and −0.47kg/THI Ra for the maritime region. Based on statistical information criteria, identified thresholds for THI Bo should be given preference over THI Ra when applying genetic studies on heat stress in German Holstein cows.

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Information on equine stress levels are important in evaluating many aspects of horse management and training. For example, for correct assessment of equine welfare, implications of training and handling procedures, success of training and the interpretation of equine temperament. Stress is a generic concept describing the body's reaction to external stimuli, including both physiological and psychological factors. Therefore, by definition, the assessment of psychological stress in the exercising horse encompasses the problem of teasing apart the psychological and physiological factors both of which result in stress responses.. The present paper reviews the existing literature on various measures of stress taken specifically in the context of equitation science. Particular attention has been paid to short-term effects, and commonly used measurements of short-term stress include heart rate, a number of heart rate variability parameters, blood or saliva cortisol levels, eye temperature, and various behaviour parameters including in particular behaviour patterns presumably indicative of conflict with the rider's/trainer's aids. Inspection of the individual studies' results revealed that disagreement between these different measures of stress is commonplace. For physiological parameters, the largest proportion of agreement (i.e. both parameters simultaneously indicated either higher, non-significant or lower stress compared to a control treatment) was found for heart rate and heart rate variability parameters, while generally limited agreement was found for cortisol and cardiovascular parameters. It appears that cortisol levels may not be particularly useful for assessment of the valence of a situation in the exercising horse as cortisol levels are predominantly linked to activity and exercise levels. Although heart rate variability parameters reflect in theory more closely sympathovagal balance compared to cortisol levels, great care has to be taken regarding the use of appropriate equipment, time-frames, as well as raw data correction. In spite of its widespread and apparently successful use, popular equipment may in fact not be accurate enough under 2 field conditions. Eye temperature is another promising parameter for assessment of psychological stress, but the technique is likewise susceptible to application errors. Given the high susceptibility of physiological parameters to errors at various experimental stages, behavioural rather than physiological parameters may in fact provide more accurate measures of valence when conducting experiments in the exercising horse. Behavioural parameters that appear to be particularly practical in assessing stress in ridden horses' behaviour are frequencies of behaviour patterns indicative of conflict. However, while increased frequencies of behaviour patterns indicative of conflict are a good indicator of stress, the absence of conflict behaviour does not provide proof of the absence of stress due to the possible occurrence of conditions such as Learned Helplessness. In future...

von Borstel (2010). A comparison of rein tension of the rider's dominant and non-dominant hand and the inuence of the horse's laterality. AbstractThe purpose of the present study was to investigate the effect of the horse's laterality on the symmetry of rein tension in right-handed riders. Eleven right-handed riders rode both a right-lateralized (RL) and a left-lateralized (LL) horse. Rein tension was measured during three circles of walk, trot and canter and four walk-halt transitions in each direction. Tensions were recorded continuously using a rein tension meter. The LL horse was ridden with significantly stronger mean tension in the left rein than in the right rein (1.5 vs. 1.4 kg; P ¼ 0.0352). Significantly more tension was applied to the outside rein in a clockwise (1.4 vs. 1.2 kg; P ¼ 0.0202), but not in a counterclockwise, direction (1.3 vs. 1.2 kg; P ¼ 0.49). Less minimum tension (0.06 vs. 0.29 kg) and greater maximum (6.4 vs. 3.9 kg) and range of tension (6.3 vs. 3.6 kg) occurred in the left rein of the RL horse (P , 0.0001) and the right rein of the LL horse (0.37 vs. 0.08 kg, 4.8 vs. 7.4 kg, 4.3 vs. 7.3 kg respectively; P , 0.0001). The results of the present study indicate that the different utilization of both reins is likely to be influenced by the laterality of both horse and rider. These findings may have important implications for equine training, since consistency of reinforcement is an important factor for equine learning success.

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