Thermography and physiology of stress in dairy calves in outdoor holding pens covered with geosynthetics/Termografia e fisiologia do estresse em bezerras mantidas em bezerreiros tropicais cobertos com geossinteticos.

Citation metadata

Publisher: ATECEL--Associacao Tecnico Cientifica Ernesto Luiz de Oliveira Junior
Document Type: Article
Length: 4,897 words

Document controls

Main content

Abstract :

HIGHLIGHTS: The use of shading for dairy calves reduces thermal discomfort in tropical regions. Geosynthetics can be used as cover material in outdoor holding pens for dairy calves. The physiological responses of calves are affected by the roofing materials used in the rural installations. This study aimed to assess the environmental variables, thermal comfort indices and physiological responses of calves in outdoor holding pens shaded with geosynthetics. Twenty crossbred females (Giroland, Jersey and Holstein) in the suckling phase (from birth to 90 days old) with an average initial live weight of 40.6 kg were used. A completely randomized block design was used, in a 4 * 3 factorial scheme with five replicates. The roofing materials (polyethylene mesh, geocomposite drainage layer, nonwoven geotextile and woven geotextile) were the first factor and time periods (8 to 10 a.m., 12 to 2 p.m. and 4 to 6 p.m.) the second factor. The following environmental variables were measured to calculate thermal comfort indices: temperature-humidity index, black globe-humidity index and enthalpy. The physiological variables analyzed were respiratory rate, rectal temperature and skin temperature. Environmental variables and thermal comfort indices did not differ between the different roof types, however, a significant difference (p Key words: dairy cows, thermal images, shading, physiological variables Este estudo teve como objetivo avaliar as variaveis ambientais, indices de conforto termico e respostas fisiologicas de bezerras criadas em bezerreiro do sistema tropical sombreados com geossinteticos. Foram avaliadas 20 femeas das racas (Girolando, Jersey e Holandesa) com peso inicial medio de 40.6 kg durante a fase de aleitamento (nascimento ate 90 dias de idade). O delineamento experimental foi de blocos casualizados completos, aplicado em um arranjo fatorial 4*3, com 5 repeticoes. Os materiais de cobertura (malha de polietileno, geocomposto drenante, geotextilnao-tecido e geotextiltecido) foram o primeiro fator e os periodos do dia (08 as 10,12 as 14 e 16 as 18 horas) foram o segundo fator. Foram mensuradas as variaveis ambientais e calculados os indices de conforto termico: indice de temperatura e umidade, indice de temperatura do globo negro e umidade e entalpia. As variaveis fisiologicas estudadas foram frequencia respiratoria, temperatura retal e temperatura de superficie corporal. Nao houve diferenca significativa para as variaveis ambientais e indices de conforto termico entre as coberturas, entretanto, houve diferenca significativa (p Palavras-chave: bovinos leiteiros, imagens termograficas, sombreamento, variaveis fisiologicas

Source Citation

Source Citation   

Gale Document Number: GALE|A674989398