Pupillary stress index: A new thermal comfort index for crossbred goats/Indice de estresse pupilar: Um novo indice de conforto termico para caprinos mesticos

Goats are homeothermic animals considered as rustic from the bioclimatic point of view, but the reduction of their productive efficiency may occur in unfavorable thermal conditions. The present study was carried out to evaluate pupil dilation as an indicator of thermal stress in Boer crossbred goats...

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Published in:Revista brasileira de engenharia agrícola e ambiental 2018-12, Vol.22 (12), p.866
Main Authors: Lopes Neto, Jose P, Marques, Jordanio I, Furtado, Dermeval A, Lopes, Fernanda F. de M, Borges, Valeria P, Araujo, Tiago G.P
Format: Article
Language:English
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Summary:Goats are homeothermic animals considered as rustic from the bioclimatic point of view, but the reduction of their productive efficiency may occur in unfavorable thermal conditions. The present study was carried out to evaluate pupil dilation as an indicator of thermal stress in Boer crossbred goats maintained under controlled environmental conditions. Six male crossbred goats of the Boer breed were distributed in a completely randomized design submitted to temperatures of 26, 29 and 33 [degrees]C. The pupillary dilation and pupillary temperature, respiratory frequency, heart rate, surface and rectal temperatures were monitored. The significant increase in physiological responses occurred in response to the increase in air temperature. An increase of pupillary dilation was observed in the animals with the elevation of the air temperature, with an increase of 26.96 mm2 in pupillary area when comparing the temperatures 26 and 33 [degrees]C, and it was possible to establish a correlation between air temperature and pupillary diameter increase, named pupillary stress ratio (PSR). Key words: Physiology pupillometry thermal stress physiological responses Os caprinos sao animais homeotermicos considerados rusticos do ponto de vista bioclimatico. Porem, em condicoes termicas desfavoraveis, pode ocorrer a reducao de sua eficiencia produtiva. Realizou-se o presente estudo com o objetivo de avaliar a dilatacao pupilar como indicador do estresse termico em caprinos mesticos Boer, mantidos em condicoes ambientais controladas. Seis caprinos machos mesticos da raca Boer foram distribuidos em delineamento inteiramente casualizado e submetidos as temperaturas de 26, 29 e 33 [degrees]C. Foram monitoradas a dilatacao e temperatura pupilar, frequencia respiratoria, frequencia cardiaca, temperatura superficial e retal. Ocorreu a elevacao nas respostas fisiologicas em razao do aumento da temperatura do ar. Constatou-se aumento da dilatacao pupilar dos animais com a elevacao da temperatura do ar, observando-se um acrescimo de 26,96 mm2 de area pupilar quando comparadas as temperaturas de 26 e 33 [degrees]C, sendo possivel estabelecer uma correlacao entre temperatura do ar e aumento do diametro pupilar chamado de razao de estresse pupilar (REP). Palavras-chave: Fisiologia pupilometria estresse termico respostas fisiologicas
ISSN:1415-4366
1807-1929
DOI:10.1590/1807-1929/agriambi.v22n12p866-871