Investigação

Início / Investigação / Apresentações / Effect of shade after exposure to direct solar radiation on body temperature dynamic responses in Alentejana and Limousine beef cattle

Effect of shade after exposure to direct solar radiation on body temperature dynamic responses in Alentejana and Limousine beef cattle

Ano
2001
Abstract

The study concerns a comparative evaluation of the heat loss capacity of Alentejana and Limousine cattle breed when submitted to different thermal environment. The study was conducted during summer (June/July of 1998) in Southeast Portugal, a Mediterranean climate region with summer temperature usually over 30ºC. Twelve heifers were used – six Alentejana (native cattle breed) weighting 248 ± 12 kg, and six Limousine weighting 286 ± 19 kg. Body temperature was measured by telemetry. Temperature transmitters (MiniMitter) were implanted 2 months before measurements. During the study, the two breeds remain separates in two contiguous lots. In the first period, between 12:00 p.m. and 14:00 p.m. the heifers were kept under direct solar radiation. In the following two hours animals were kept in shade. Core temperature was measured in all animals every 10 minutes. During those periods no food or water was available. That procedure was repeated in six different days with the same animals. Meteorological data were also collected simultaneously with core temperature. The results obtained show that Alentejana breed has lower initial core temperature than Limousine (38,50ºC vs. 38.65ºC). During exposure to direct solar radiation Limousine has shown initial higher thermal inertia. In spite of that, after two hours under direst solar radiation, Limousine shows higher significant body temperature (39,31ºC) than Alentejana (39,10ºC). After the passage to the shade Alentejana’s body temperature starts to decrease faster than Limousine. After 80 minutes in shade Alentejana had completely recovered the initial body temperature. After two hours in shade Limousine were still enable to completely recover their initial temperature (it remain 38,8ºC). Showing therefore less capacity to dissipate heat storage. The Alentejana breed has shown final body temperature lower than initial (38,43ºC), which could be interpreted as a compensatory response to acute heat stress. The results show that Alentejana has more efficient thermolysis, therefore this cattle breed seems to be more adequate than Limousine breed in regions with higher radiative temperatures

Palavras Chave

beef cattle; heat balance; solar radiation; thermoregulation.

Tipo de Apresentação
Comunicação oral
Tipo de Revisão
Internacional
Âmbito Geográfico
Internacional
Situação
Publicado
Referência

Pereira, A.; Junior, F.; Titto, E.; Almeida, A. (2001). Effect of shade after exposure to direct solar radiation on body temperature dynamic responses in Alentejana and Limousine beef cattle. VI International Livestock Environment Symposium, pp. 455-460. American Society of Agricultural and Biological Engineers. Louisville, Kentuky, USA.