Assessment of welfare from physiological and behavioural responses of New Zealand dairy cows exposed to cold and wet conditions
There is a need to assess the welfare of dairy cows that live outdoors under cold and wet conditions. This study combined a number of techniques to measure stress and make an assessment of welfare in this situation. Two groups of ten non-pregnant, non-lactating Holstein Friesian cows were exposed to a week of wind and rain (WR) or housed indoors (I) with pre- and post-treatment weeks indoors in a cross-over design. Wind and rain consisted of continual air movement (7.1 kph) using fans, water sprinkling for 15 min (3.0 mm) per hour, a mean temperature of 3.4°C and wind chill of –0.3°C. Internal body temperature was recorded every ten min and behaviour for 16 h per day. Blood, faeces and infrared temperatures were sampled at 0800h each morning during treatment weeks, and three times per week during pre- and post-treatment weeks. All cows were challenged with 2 ml Leptoshield Vaccine (CSL Animal Health, Australia) subcutaneously after 3 days of cold exposure to test immune responses. During WR, cows spent a greater proportion of time standing and less time lying down and eating than during I. Infrared temperatures were lower during WR than I in both dorsal and orbital (eye) regions. There was a distinct diurnal pattern of internal body temperature which had a greater amplitude during WR than I resulting from both a lower minimum and a higher maximum. The time of the minimum was 40 min later for WR than I. The overall mean body temperature was 0.07°C higher in WR than I. There were greater increases in plasma and faecal cortisol during WR than I, respectively. Total T4 was higher during WR than I. Non-esterified fatty acid concentration was higher in the week following WR than I. Total white blood cell numbers were lower during WR than I. No treatment differences were found for creatine kinase or for tumour necrosis factor, heat shock protein 90, interleukin 6 or interferon gamma expression in response to vaccination. In conclusion, this study applied a suite of stress measures to dairy cows exposed to extreme cold and wet conditions. Together, these measures indicated activation of the stress axis, physiological and behavioural adaptations to cold and a reduction in welfare. A number of these measures could be used to assess welfare under cold conditions on farms.
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