Article (Scientific journals)
Thermotolerance indicators related to production and physiological responses to heat stress of holstein cows
Amamou, Hajer; Beckers, Yves; Mahouachi, M. et al.
2019In Journal of Thermal Biology, 82, p. 90-98
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Keywords :
Heat stress; Heat-tolerance; Holstein cattle; Individual responses; Physiological trait; Production trait; Article; Tunisia; Animals; Cattle; Female; Heat Stress Disorders; Heat-Shock Response; Humidity; Lactation; Milk; Thermotolerance
Abstract :
[en] Heat stress (HS) adversely influences dairy cattle welfare and productivity. This study aimed to investigate the effects of HS on production and physiological parameters of Holstein cows. Two experiments each lasted 6 weeks were conducted in four Tunisian farms, firstly during summer under HS (n = 80, THI = 77) and later during autumn under thermo-neutral (n = 80, THI = 54) conditions. Respiration rate (RR), skin temperature (ST), rectal temperature (RT) and milk yield were measured, and milk samples were collected on 2 days every week during each experimental period. Temperature and relative humidity were measured inside the barn to calculate the temperature-humidity index (THI). Mixed models were used to evaluate the effects of period and the relationships between THI and physiological and production traits. Reaction norm models were applied to quantify the individual responses of cows across the trajectory of THI during the HS period. A clustering methodology was developed to identify tolerant and sensitive cows to HS based on their slope for response of physiological and production traits during HS period. In summer, RR (61 breaths/min) and ST (37.7 °C) were 2.3- and 1.3-fold higher, whereas milk yield per milking was 24% lower compared with thermo-neutral conditions. Linear relationship between THI and RR, ST and RT was observed and showed increases by 2 breaths/min, 0.5 °C and 0.04 °C per increase in one THI unit, respectively. Inversely, milk, fat and protein yields showed a drop of 0.13 kg, 0.4 g and 0.3 g per milking per increase in one THI unit, respectively. Cows qualified to be heat tolerant by our work tended to have higher RR, ST, and RT and lower to almost no decay in milk yield compared to cows qualified to be heat sensitive. Specifically, RR could be used as a reliable indicator for thermotolerance. The results of this study deepen our understanding of different aspects of HS resilience. © 2019 Elsevier Ltd
Disciplines :
Animal production & animal husbandry
Author, co-author :
Amamou, Hajer ;  Université de Liège - ULiège > Terra
Beckers, Yves  ;  Université de Liège - ULiège > Département GxABT > Ingénierie des productions animales et nutrition
Mahouachi, M.;  High School of Agriculture of Kef, University of Jendouba, Le Kef, 7119, Tunisia
Hammami, Hedi ;  AgroBioChem, Gembloux Agro-Bio Tech, University of Liège, Passage des Déportés 2, Gembloux, 5030, Belgium
Language :
English
Title :
Thermotolerance indicators related to production and physiological responses to heat stress of holstein cows
Publication date :
2019
Journal title :
Journal of Thermal Biology
ISSN :
0306-4565
Publisher :
Elsevier Ltd
Volume :
82
Pages :
90-98
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
MHESR - Ministère de l'Enseignement Supérieur et de la Recherche Scientifique [TN]
Available on ORBi :
since 13 March 2020

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