SciELO - Scientific Electronic Library Online

 
vol.34 issue6Reproductive performance of beef heifers bred at 18 or 24 months of ageRelationship between ultrasound measurements and fat thickness or rib eye area in carcass of beef cattle author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

Related links

Share


Revista Brasileira de Zootecnia

Print version ISSN 1516-3598On-line version ISSN 1806-9290

Abstract

STARLING, Josiane Maria Cardoso et al. Seasonal variation of thyroid hormones and cortisol of sheep in tropical environment. R. Bras. Zootec. [online]. 2005, vol.34, n.6, pp.2064-2073. ISSN 1516-3598.  http://dx.doi.org/10.1590/S1516-35982005000600032.

The variation of cortisol and thyroid hormones in Corriedale sheep bred in a tropical environment was evaluated. Fourteen males and seven females were observed in a climatic chamber at 45ºC for nine days, eight hours per day. Rectal temperature (TR), respiratory rate (FR), air temperature (TA) and air humidity (PV) were recorded. The animals were ranked according to their responses for TR and FR and then the five highest (A group) and five lowest (NA group) ranked animals were selected. These ten animals were moved to a pen where they were observed along one year for TR and FR two times a day, and blood-sampled once a week. The results showed differences for T3, T4, and cortisol concentrations, which were attributed to variations in TA and PV. Cortisol concentrations were higher and T3 and T4 ones were lower under increased TA and PV. Correlations of TA and PV with cortisol values were r = .224 and r = .395 respectively. The negative correlations of TA with T3 (r = -.151) and T4 (r = -.156) showed that increase in TA may be followed by decrease in the metabolic rate. No significant difference for all variables investigated was found between the two groups, thus it is not recommended the use of TR and FR as the only criteria to evaluate sheep performance in tropical environments.

Keywords : cortisol; sheep; thyroid hormones; tropical environment.

        · abstract in Portuguese     · text in Portuguese     · Portuguese ( pdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License