Document Detail

Effect of thermal stress on physiological parameters, feed intake and plasma thyroid hormones concentration in Alentejana, Mertolenga, Frisian and Limousine cattle breeds.
MedLine Citation:
PMID:  17578605     Owner:  NLM     Status:  MEDLINE    
The aim of the present study was to assess the heat tolerance of animals of two Portuguese (Alentejana and Mertolenga) and two exotic (Frisian and Limousine) cattle breeds, through the monitoring of physiological acclimatization reactions in different thermal situations characterized by alternate periods of thermoneutrality and heat stress simulated in climatic chambers. In the experiment, six heifers of the Alentejana, Frisian and Mertolenga breeds and four heifers of the Limousine breed were used. The increase in chamber temperatures had different consequences on the animals of each breed. When submitted to heat stress, the Frisian animals developed high thermal polypnea (more than 105 breath movements per minute), which did not prevent an increase in the rectal temperature (from 38.7 degrees C to 40.0 degrees C). However, only a slight depression in food intake and in blood thyroid hormone concentrations was observed under thermal stressful conditions. Under the thermal stressful conditions, Limousine animals decreased food intake by 11.4% and blood triiodothyronine (T3) hormone concentration decreased to 76% of the level observed in thermoneutral conditions. Alentejana animals had similar reactions. The Mertolenga cattle exhibited the highest capacity for maintaining homeothermy: under heat stressful conditions, the mean thermal polypnea increased twofold, but mean rectal temperature did not increase. Mean food intake decreased by only 2% and mean T3 blood concentration was lowered to 85,6% of the concentration observed under thermoneutral conditions. These results lead to the conclusion that the Frisian animals had more difficulty in tolerating high temperatures, the Limousine and Alentejana ones had an intermediate difficulty, and the Mertolenga animals were by far the most heat tolerant.
Alfredo M F Pereira; Flávio Baccari; Evaldo A L Titto; J A Afonso Almeida
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-06-20
Journal Detail:
Title:  International journal of biometeorology     Volume:  52     ISSN:  1432-1254     ISO Abbreviation:  Int J Biometeorol     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2007-12-18     Completed Date:  2009-04-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0374716     Medline TA:  Int J Biometeorol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  199-208     Citation Subset:  IM    
Instituto de Ciências Agrárias Mediterrânicas, Universidade de Evora, Portugal.
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MeSH Terms
Acclimatization / physiology*
Cattle / classification,  physiology*
Computer Simulation
Eating / physiology*
Heat-Shock Response / physiology*
Models, Biological*
Species Specificity
Thyroid Hormones / blood*
Reg. No./Substance:
0/Thyroid Hormones

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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