Painéis fotovoltaicos: alternativa de sombreamento para novilhas leiteiras
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Data
2020-04-17
Autores
Faria, Ana Flávia Prado Antunes de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste estudo foi avaliar a carga térmica radiante na sombra projetada por painéis fotovoltaicos e determinar o impacto nas respostas fisiológicas e comportamentais de novilhas leiteiras no uso ou não de sombra. Para tanto, foram utilizadas sete novilhas mestiças 7/8 da raça Holandesa, com idade média de 10 meses, manejadas em piquete com estrutura de sombreamento artificial provido por um conjunto de painéis fotovoltaicos. As temperaturas corporais (vaginal, temperatura da superfície da pele e do pelame, °C) e frequência respiratória (respirações minutos-1 ) na sombra ou expostas à radiação solar foram avaliadas durante 24 horas a cada 5 minutos. Observações comportamentais foram realizadas das 08:00 as 17:00h, em intervalos regulares de 5 minutos. As variáveis meteorológicas (temperatura e umidade do ar, irradiância solar e velocidade do vento) foram medidas em intervalos regulares de 1 minuto durante 24 horas. A estrutura de sombra foi composta por 10 painéis fotovoltaicos, projetando 19,3 m² de sombreamento, gerando uma média mensal de 405,78 kWh. Na primeira hora do dia, as novilhas despenderam 90% do tempo expostas à radiação solar, permanecendo em atividade de pastejo. Com o aumento da temperatura do ar e radiação solar, o tempo gasto na sombra nas atividades de ruminação e ócio, em pé ou deitado aumentou até 13:00h, totalizando cerca de 80% do tempo nessas atividades. Aparentemente, a variação diária da temperatura vaginal dos animais não foi afetada pelo uso da sombra projetada pelos painéis. As temperaturas da superfície da pele e do pelame atingem os valores mais altos quando os animais são expostos à radiação solar. A frequência respiratória exibe o mesmo comportamento das temperaturas da superfície, e por volta de 14:00h atingindo uma média de 92 respirações minutos-1 . A carga térmica radiante foi cerca de 27% menor sob a estrutura de sombra, o que mostra que os animais usam sombra porque oferece uma melhor condição de conforto térmico, controlando as temperaturas internas e de superfície e a taxa respiratória. Portanto, fornecer sombra dos painéis fotovoltaicos ajuda na termorregulação dos animais, melhorando seu bem-estar e gerando energia limpa e renovável.
The aim of this study was to evaluate the radiant heat load in the shadow projected by photovoltaic panels and to determine the impact on t he physiological and behavioral responses of dairy heifers in the use or not of shade. For this purpose, seven 7/8 Holstein heifers, with an average age of 10 months, were used in paddocks with artificial shading structure provided by a set of photovoltaic Body temperatures (vaginal, skin and hair coat panels. surface temperature, ° C) and respiratory rate (breaths min asse1 ) in the shade or exposed to solar radiation were ssed for 24 hours every 5 minutes. Behavioral observations were made from 08:00 to 17 :00, at regular intervals of 5 minutes. The meteorological variables (air temperature and humidity, solar irradiance and wind speed) were measured at regular intervals of 1 minute for 24 hours. The shade structure was composed of 10 photovoltaic panels, pr ojecting 19.3 m² of shading, generating a monthly average of 405.78 kWh. In the first hour of the day, heifers spent 90% of their time exposed to solar radiation, remainin g in grazing activity. With the increase in air temperature and solar radiation, the time spent in the shade in the activities of rumination and idlying , standing or lying increased until 13:00, totaling about 80% of the time in these activities. Apparentl y, the daily variation of the animals' vaginal temperature was not affected by the us e of the shade projected by the panels. The surface temperatures of the skin and hair coat surface reach the highest values 14 when animals are exposed to solar radiation. The respiratory rate exhibits the same behavior as the surface temperatures, and at about :00 reaching an average of 92 breaths minutes about 27% lower 1 . The radiant heat load was under the shade structure, which shows that animals use shade because the y offer a better condition of thermal comfort, controlling i nternal and surface temperatures and the respiratory rate. Therefore, providing shade from the photovoltaic panels helps in the thermoregulation of animals, improving their wel and generating Keywords : clean and renewable energy.
The aim of this study was to evaluate the radiant heat load in the shadow projected by photovoltaic panels and to determine the impact on t he physiological and behavioral responses of dairy heifers in the use or not of shade. For this purpose, seven 7/8 Holstein heifers, with an average age of 10 months, were used in paddocks with artificial shading structure provided by a set of photovoltaic Body temperatures (vaginal, skin and hair coat panels. surface temperature, ° C) and respiratory rate (breaths min asse1 ) in the shade or exposed to solar radiation were ssed for 24 hours every 5 minutes. Behavioral observations were made from 08:00 to 17 :00, at regular intervals of 5 minutes. The meteorological variables (air temperature and humidity, solar irradiance and wind speed) were measured at regular intervals of 1 minute for 24 hours. The shade structure was composed of 10 photovoltaic panels, pr ojecting 19.3 m² of shading, generating a monthly average of 405.78 kWh. In the first hour of the day, heifers spent 90% of their time exposed to solar radiation, remainin g in grazing activity. With the increase in air temperature and solar radiation, the time spent in the shade in the activities of rumination and idlying , standing or lying increased until 13:00, totaling about 80% of the time in these activities. Apparentl y, the daily variation of the animals' vaginal temperature was not affected by the us e of the shade projected by the panels. The surface temperatures of the skin and hair coat surface reach the highest values 14 when animals are exposed to solar radiation. The respiratory rate exhibits the same behavior as the surface temperatures, and at about :00 reaching an average of 92 breaths minutes about 27% lower 1 . The radiant heat load was under the shade structure, which shows that animals use shade because the y offer a better condition of thermal comfort, controlling i nternal and surface temperatures and the respiratory rate. Therefore, providing shade from the photovoltaic panels helps in the thermoregulation of animals, improving their wel and generating Keywords : clean and renewable energy.
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Palavras-chave
Comportamento, Novilha leiteira, Painel fotovoltaico, Fisiológico, Sombra