title: Thermal equilibrium of goats.
abstract: The effects of air temperature and relative humidity on thermal equilibrium of goats in a tropical region was evaluated. Nine non-pregnant Anglo Nubian nanny goats were used in the study. An indirect calorimeter was designed and developed to measure oxygen consumption, carbon dioxide production, methane production and water vapour pressure of the air exhaled from goats. Physiological parameters: rectal temperature, skin temperature, hair-coat temperature, expired air temperature and respiratory rate and volume as well as environmental parameters: air temperature, relative humidity and mean radiant temperature were measured. The results show that respiratory and volume rates and latent heat loss did not change significantly for air temperature between 22 and 26°C. In this temperature range, metabolic heat was lost mainly by convection and long-wave radiation. For temperature greater than 30°C, the goats maintained thermal equilibrium mainly by evaporative heat loss. At the higher air temperature, the respiratory and ventilation rates as well as body temperatures were significantly elevated. It can be concluded that for Anglo Nubian goats, the upper limit of air temperature for comfort is around 26°C when the goats are protected from direct solar radiation.
authors.affiliation: Laboratory of Animal Biometeorology, Animal Science Department, Universidade Estadual Paulista (UNESP), Via Paulo Donato Castellane s/n, 14884-900 Jaboticabal, SP, Brazil. Electronic address: alex.maia@fcav.unesp.br.
authors.forename: Alex S C
authors.initials: AS
authors.lastname: Maia
authors.affiliation: Animal Science Department, Universidade Estadual de Maringá (UEM), Av. Colombo, 5790, 87020-900 Maringá, PR, Brazil. Electronic address: sheila_tn@terra.com.br.
authors.forename: Sheila T
authors.initials: ST
authors.lastname: Nascimento
authors.affiliation: Laboratory of Animal Biometeorology, Animal Science Department, Universidade Estadual Paulista (UNESP), Via Paulo Donato Castellane s/n, 14884-900 Jaboticabal, SP, Brazil. Electronic address: carolnagib@yahoo.com.br.
authors.forename: Carolina C N
authors.initials: CC
authors.lastname: Nascimento
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA. Electronic address: kgg1@cornell.edu.
authors.forename: Kifle G
authors.initials: KG
authors.lastname: Gebremedhin
mesh_terms: D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation; D002153:Calorimetry, Indirect / Q000295:instrumentation; D004867:Equipment Design; D005260:Female; D006041:Goats / Q000502:physiology*; D006358:Hot Temperature; D006813:Humidity; D010101:Oxygen Consumption; D013696:Temperature; D022722:Thermogenesis; D014329:Tropical Climate
keywords: Goats; Latent heat loss; Sensible heat loss; Thermogenesis; Thermoregulation