Responses of dairy cows to short-term heat stress in controlled-climate chambers

Garner, J. B., Douglas, M., Williams, S. R. O., Wales, W. J., Marett, L. C., DiGiacomo, K., Leury, B. J. and Hayes, B. J. (2017) Responses of dairy cows to short-term heat stress in controlled-climate chambers. Animal Production Science, 57 7: 1233-1241. doi:10.1071/AN16472

Author Garner, J. B.
Douglas, M.
Williams, S. R. O.
Wales, W. J.
Marett, L. C.
DiGiacomo, K.
Leury, B. J.
Hayes, B. J.
Title Responses of dairy cows to short-term heat stress in controlled-climate chambers
Journal name Animal Production Science   Check publisher's open access policy
ISSN 1836-5787
Publication date 2017-01-01
Sub-type Article (original research)
DOI 10.1071/AN16472
Open Access Status Not yet assessed
Volume 57
Issue 7
Start page 1233
End page 1241
Total pages 9
Place of publication Clayton, VIC, Australia
Publisher C S I R O Publishing
Language eng
Abstract The objective of the present research was to describe the physiological and production responses of lactating dairy cows during and after sudden exposure to temperate-climate heat-wave conditions, compared with cows in thermoneutral conditions. Twelve lactating multiparous Holstein-Friesian dairy cows were housed in controlled-climate chambers for 4 days. Six were exposed to a short-term temperature and humidity challenge (THc, diurnal temperature and humidity fluctuations inducing moderate heat stress; temperature humidity index 74-84) and six cows were exposed to thermoneutral conditions (THn, temperatur humidity index 55-61). Cows were also measured during a 7-day pre-experimental and 14-day post-experimental period. Physiological indicators of heat stress were measured, including rectal and vaginal temperature and respiration rate, which indicated that the THc in controlled-climate chambers induced moderate heat stress. The cows exposed to the 4-day THc reduced their milk yield by 53% and their dry-matter intake by 48%, compared with the cows in the THn treatment. Milk yield of THc cows returned to pre-experimental milk yield by Day 7 and dry-matter intake by Day 4 of the post-experimental period. The short-term heat challenge induced metabolic adaptations by mobilising adipose tissue, as indicated by increased non-esterified fatty acids, and amino acids from skeletal muscle, as indicated by increased urea nitrogen to compensate for reduced nutrient intake and increased energy expenditure. Endocrine responses included greater prolactin concentrations, which is associated with thermoregulation and water metabolism. The cows exposed to THc displayed production and physical responses that facilitated lower metabolic heat production and greater heat dissipation in an attempt to maintain homeostasis during the short-term heat exposure. These results indicated that the conditions imposed on the cows in the controlled-climate chambers were sufficient to induce heat-stress responses and adversely affected production in the lactating dairy cow, and the delay between the return to normal feed intake and milk yield following the heat challenge suggests a period of metabolic recovery was occurring.
Keyword Endocrine regulation
Heat acclimation
Moderate heat stress
Stress responses
Thermal physiology
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
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Queensland Alliance for Agriculture and Food Innovation
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