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Thermolysis capacity, reactivity and shade use in sheep


The main objective is to assess the thermolysis capacity in sheep breeds and investigate the influence on shade seeking. The work will consist of two stages held at the Faculdade de Zootecnia e Engenharia de Alimentos - FZEA/USP, located in Pirassununga, SP. 60 Santa Ines females White Dorper parous will be studied. In the first phase rectal temperatures will be recorded for the evaluation of heat tolerance, indicating thermolysis capacity. The rectal temperature is recorded for 13h, after two hours of rest in the shade, at 14h, one hour after sun exposure, and at 14:30h, after 30 minutes of rest in the shade. At the same time of rectal temperatures samples it will be measured surface temperature, sweating rate, respiratory rate, and blood will be taken for plasma cortisol samples and HSP70 will be also measured from leukocytes. The reactivity of animals will be evaluated by flight speed and responsiveness of management in the corral during samples collection. All analysis will be carried out using univariate procedures, CORR, GLM and MIXED (SAS). The second step will use the same 60 females and behavior will be observed on pasture for natural shade seeking. Behavioral variables will included: standing posture, stay in the shade and daily activities (eating, drinking, ruminating, idling), and they will be observed every 15 minutes during the day, starting after sunrise until sunset. It is expected to find relationships between the use of shade and thermolysis capacity. (AU)

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