E-resources
Peer reviewed
Open access
-
de Melo Costa, Cíntia Carol; Campos Maia, Alex Sandro; Brown-Brandl, Tami M.; Chiquitelli Neto, Marcos; de França Carvalho Fonsêca, Vinicius
Journal of thermal biology, 20/May , Volume: 74Journal Article
The aim of this work was to evaluate the diurnal patterns of physiological responses and the thermal regulation of adult Nellore bulls. Six 30-mo-old Nellore bulls (669 ± 65 kg BW) were randomly assigned to four 6-h periods in a Latin Square design such that measurements of each animal cover a 24-h cycle. Meteorological variables (air temperature, relative humidity, local solar irradiance, ultraviolet radiation, wind speed and black globe temperature) were recorded at regular one-minute intervals with an automated weather station. Respiratory rate, ventilation rate, oxygen, carbon dioxide, methane, saturation pressure, air temperature of the exhaled air, saturation pressure in the air leaving the ventilated capsule placed over the animal surface, hair coat, skin surface and rectal temperature were assessed. The thermal equilibrium was determined according to the principles of the first law of thermodynamics using biophysical equations. Animals were evaluated in an area which was protected from solar radiation, rain, and had a range of ambient air temperature between 20.57 ± 0.07 and 30.86 ± 0.07 °C. Percentage of O2 and CO2 in the exhaled air changed moderately (P < 0.0001) throughout the 24 h, which resulted in an average metabolic heat production of 151.45 ± 13.60 W m-2. At the largest thermal gradient (TS - TA; from 24:00–07:00 h), heat transferred by long wave radiation and surface convection corresponded to near 60% of the metabolism. At 11:00 h the ambient temperature approached 29 °C and latent heat became the main way to cool the body. From this time until 17:00 h, cutaneous evaporation represented approximately 53% of total heat loss. In conclusion, results of the present study seem to be a good indicator of lower energy expenditure for body thermal regulation, high heat tolerance and adaptation of Nellore cattle to the tropical environment. •Circadian period of thermal equilibrium of Nellore cattle was investigated.•Average of metabolic heat production of Nellore bulls was 151.45 ± 13.60 W m-2.•Air temperature above 29 °C, cutaneous evaporation is the main way to mantain Nellore's thermoregulation.•Respiratory evaporation present minor significance for thermal regulation of Nellore.
![loading ... loading ...](themes/default/img/ajax-loading.gif)
Shelf entry
Permalink
- URL:
Impact factor
Access to the JCR database is permitted only to users from Slovenia. Your current IP address is not on the list of IP addresses with access permission, and authentication with the relevant AAI accout is required.
Year | Impact factor | Edition | Category | Classification | ||||
---|---|---|---|---|---|---|---|---|
JCR | SNIP | JCR | SNIP | JCR | SNIP | JCR | SNIP |
Select the library membership card:
If the library membership card is not in the list,
add a new one.
DRS, in which the journal is indexed
Database name | Field | Year |
---|
Links to authors' personal bibliographies | Links to information on researchers in the SICRIS system |
---|
Source: Personal bibliographies
and: SICRIS
The material is available in full text. If you wish to order the material anyway, click the Continue button.