Thermoregulatory response of Brangus heifers to naturally occurring heat exposure on pasture
| Autor: | Raluca G. Mateescu, Heather Hamblen, Pascal A. Oltenacu, Peter J. Hansen, A. M. Zolini |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Coat Hot Temperature Biology Pasture Body Temperature 03 medical and health sciences Animal science Environmental Animal Science Genetics medicine Animals Relative humidity Animal Fur Temperament geography geography.geographical_feature_category Dry-bulb temperature 0402 animal and dairy science Humidity 04 agricultural and veterinary sciences General Medicine Repeatability Thermoregulation 040201 dairy & animal science 030104 developmental biology medicine.anatomical_structure Vagina Cattle Female Animal Science and Zoology Heat-Shock Response Body Temperature Regulation Food Science |
| Zdroj: | Journal of Animal Science. 96:3131-3137 |
| ISSN: | 1525-3163 0021-8812 |
| Popis: | Heat stress is a cause of major economic losses to cattle producers, especially in tropical and subtropical environments. The objectives of this study were to assess the phenotypic variability in core body temperature and sweating rate and to evaluate the effect of coat type, temperament, and BW on core body temperature and sweating rate in Brangus heifers. During August and September of 2016, 725 Brangus heifers were evaluated on pasture in four separate groups (n = 200, 189, 197, and 139). Environmental measurements of dry bulb temperature (T(db)) and relative humidity (RH) were measured every 15 min during the entire time of data collection and the temperature–humidity index (THI) was used to quantify heat-stress potential. Coat score, sweating rate, chute score, exit score, and live weight were recorded as the animals passed through the chute. Vaginal temperature was recorded every 5 min for five consecutive days. There was significant variation in vaginal temperature between heifers in the same environmental conditions (σ(2)(u) = 0.049), suggesting opportunities for selective improvements. A repeatability of 0.47 and 0.44 was estimated for sweating rate and vaginal temperature, respectively, suggesting that one measurement would be able to adequately describe the sweating capacity or ability to control the body temperature of an individual. Vaginal temperature increased as THI increased, with approximately 1 h lag time in the animal’s response. Vaginal temperature (−0.047 °C, P = 0.015) and sweating rate were lower (−5.49 ± 2.12 g/(m(2)·h), P < 0.01) for heifers that demonstrated a calmer behavior in the chute. Animals with shorter, smoother hair coats had significantly lower vaginal temperatures when compared to animals with longer hair coats (P < 0.01). Also, heavier heifers in this study maintained lower (P < 0.0001) vaginal temperature than the lighter heifers. Our results showed that hair coat, temperament, and weight influenced vaginal temperature regulation. |
| Databáze: | OpenAIRE |
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