Physiological responses and thermal equilibrium of Jersey dairy cows in tropical environment

Autor(es)

Nascimento, Sheila Tavares ^[1] ; Campos Maia, Alex Sandro ^[2] ; Carvalho Fonseca, Vinicius de Franca ^{[3, 2]} ; Nagib Nascimento, Carolina Cardoso ^[2] ; de Carvalho, Marcos Davi ^[4] ; Pinheiro, Maria da Graca ^[5]

Afiliação do(s) autor(es)

^[1] Univ Brasilia, Fac Agron & Vet Sci, Darcy Ribeiro Campus, BR-70910900 Brasilia, DF - Brazil

^[2] Sao Paulo State Univ, Innovat Grp Biometeorol Behav & Anim Welf INOBIO, Biometorol Lab, Jaboticabal - Brazil

^[3] Univ Witwatersrand, Sch Physiol, Brain Funct Res Grp, Johannesburg - South Africa

^[4] Granja Piara, 149 Tonho Nena St, BR-38703062 Patos De Minas, MG - Brazil

^[5] Agencia Paulista Tecnol Agronegocios, 2419 Bandeirantes Ave, BR-14030670 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF BIOMETEOROLOGY; v. 63, n. 11, SI, p. 1487-1496, NOV 2019.
• Citações Web of Science: 0

Resumo

Long-term assessments of thermal responses of housed Jersey cows raised in tropical conditions were performed to investigate the effect of climate environment on their physiological performance and thermal equilibrium. Twelve Jersey dairy cows with 326.28 +/- 30 kg of body weight, 17.66 +/- 1.8 of milk yield, and 165.5 +/- 6.8 of days in milking were assigned in two 12 x 12 Latin square designs. Air temperature, relative humidity, partial vapor pressure, direct and diffuse short-wave solar radiation and black globe temperature under the shade, and direct sunlight were recorded. Physiological responses as respiratory rate (R-R, breaths min(-1)), ventilation (V-E, L s(-1)), proportion (%) of oxygen (O-2) and carbon dioxide (CO2), saturation pressure (P-S[T-EXH]), and air temperature (T-EXH, degrees C) of the exhaled air were assessed protected from solar radiation and rain. Rectal temperature (T-R, degrees C), skin temperature (T-EP, degrees C), and hair coat surface temperature (T-S, degrees C) were also recorded. The thermal equilibrium was determined from biophysical equations according to the principles of the energy conservation law in a control volume. Exploratory and confirmatory analyses were performed from principal components and by the least square method, respectively. The cows were evaluated under range of ambient air temperature from 26 to 35 degrees C, relative humidity from 27 to 89%, and short-wave radiation from 0 to 729 W m(-2). Exploratory and confirmatory analyses demonstrated that a similar level of nocturnal and diurnal air temperatures evoked distinct (P < 0.05) responses for rectal (T-R, degrees C) and skin (T-EP, degrees C) temperatures, ventilation (V-E, L s(-1)), tidal volume (T-V, L breaths(-1)), and oxygen consumption ( increment O-2, %) and carbon dioxide output ( increment CO2, %), clearly revealing an endogenous rhythm dependence. In conclusion, these findings clarify how the circadian rhythmicity of the thermal environment and animal's biological clock dictate dynamics of heat generated by metabolism, dissipated to the environment and physiological parameters of the housed Jersey cows raised in tropical condition; therefore, it is fundamental to help us to understand how the Jersey dairy cows under tropics are affected by the climatic conditions, leading to better ways of the environmental management. (AU)

• Processo FAPESP: 14/09639-7 - Emissão de metano e termorregulação em bovinos: um estudo da variação circadiana em ambiente tropical
• Beneficiário: Alex Sandro Campos Maia
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Regular
• Processo FAPESP: 11/17388-6 - Efeito da radiação solar e da temperatura na emissão de metano associado com a produção calor metabólico e perda de calor latente em ruminantes
• Beneficiário: Alex Sandro Campos Maia
• Modalidade de apoio: Auxílio à Pesquisa - Regular