Author : Catherine Lussier
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (129 download)
Book Synopsis Impacts of Summer Outdoor Access on the Heat Stress and Panting Behaviour of Lactating Holstein Cows Housed in Tie-stall by : Catherine Lussier
Download or read book Impacts of Summer Outdoor Access on the Heat Stress and Panting Behaviour of Lactating Holstein Cows Housed in Tie-stall written by Catherine Lussier and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Heat stress affects the overall profitability of dairy producers as it leads to severe detrimental impacts on milk production, reproduction, and general health and welfare of husbandry animals, with estimated losses to be between $897 to $1500 million per year for the U.S. dairy industry. Based on the information gathered in our literature review, the heat load of dairy cows can be evaluated by looking at predictors of heat stress (e.g., Temperature-Humidity Index (THI)) and at clinical signs of heat stress, such as physiological responses (e.g., respiration rate) and behavioural responses (e.g., panting). The objectives of the study were to; (1) measure the impact of duration of outdoor access (1 h vs. 2 h) on the thermal comfort of lactating cows assessed through the frequency and duration of panting behaviours, and (2) evaluate the heat load status of dairy cows assessed through the frequency and intensity of panting behaviour, as well as the measure of the duration of other heat stress-related behaviours (eating, ruminating, and others) throughout the day. For this study, 15 cows paired by parity and days in milk were enrolled into one of two treatment groups: cows provided with outdoor access (Treatment; 7 cows) and cows that remained in tie stall (Control; 8 cows). Indoor and outdoor ambient temperature and relative humidity, recorded continuously every 5 min intervals, were used to calculate the THI. To assess heat load, (1) both treatment and control cows were observed simultaneously for panting behaviour using instantaneous live scan sampling (7 scans/h) for the duration of outdoor access (1 or 2 hour/day), 3 days/week for 3 consecutive weeks, and (2) all cows were recorded for 10 min at 4 specific times of the day (before outings, 30 minutes after outings, before afternoon milking, and late evenings), one day a week for 3 consecutive weeks. All Control and Outdoor cows were observed during 3 specific bouts of 1 min per video for the description of panting behaviour. Indoor and outdoor THI values were on average (± SD) 70.8 ± 2.4 and 69.0 ± 2.9, respectively. The THI values during video observations were on average 73.6 ± 3.4. Descriptive results from live scan sampling observations showed that 50% of the observations corresponded to panting cows, while that proportion reached 64% for video recording observations. Rapid movement of flanks was the most observed panting behaviour during instantaneous live scan sampling (46% of panting cows), while the most observed panting behaviour during video observations corresponded to the simultaneous movements of the flanks, head, and body (52% of panting cows). Results from our statistical analysis showed no difference for panting frequencies between the 1-hour Outdoor cows and 1-hour Control cows and the 2-hour Outdoor cows and 2-hour Control cows (LSmean ± SE; -0.5 ± 6.38; P = 0.93 and -1.3 ± 6.73; P= 0.85, respectively. Even though a numerical difference is noticeable when comparing the first hour to the second hour of treatment application of Control and Outdoor cows for the proportion of scans in which they were observed panting, no statistically significant difference application was found for both Outdoor and Control cows after correction for multiple comparisons (-27.5 ± 7.35; P = 0.0003 (n.s), and 3.9 ± 6.35; P = 0.5395, respectively. Providing lactating cows with 1 h of outdoor access in mild THI does not seem to impact their heat load status. This research study provides new information about dairy cow's thermal comfort when provided with short duration of outdoor access during the summer. Ultimately, this study contributes to the development of a new heat load assessment tool that could be routinely used by dairy producers"--