Thermal balance of Nellore cattle

Abstract

This work aimed at characterizing the thermal balance of Nellore cattle from the system of indirect calorimetry using a facial mask. The study was conducted at the Animal Biometeorology Laboratory of the São Paulo State University, Jaboticabal, Brazil. Five male Nellore weighing 750 ± 62 kg, at similar ages and body conditions were distributed in four 5 × 5 Latin squares (5 days of records and five schedules) during 20 days. Physiological and environmental measurements were obtained from the indirect calorimetry system using a facial mask. Respiratory parameters, hair coat, skin, and rectal temperature were continuously recorded. From this, metabolic heat production, sensible and latent ways of heat transfer were calculated. Metabolic heat production had an average value of 146.7 ± 0.49 W m and did not change (P > 0.05) over the range of air temperature (24 to 35 °C). Sensible heat flow reached 60.08 ± 0.81 W m when air temperature ranged from 24 to 25 °C, being negligible in conditions of temperature above 33 °C. Most of the heat produced by metabolism was dissipated by cutaneous evaporation when air temperature was greater than 30 °C. Respiratory parameters like respiratory rate and ventilation remained stable (P > 0.05) in the range of temperature studied. Under shade conditions and air temperature range from 24 to 35 °C, metabolic heat production, respiratory rate, and ventilation of mature Nellore cattle remain stable, which is indicative of low energetic cost to the thermoregulation.

Shading effect on physiological parameters and in vitro embryo production of tropical adapted Nellore heifers in integrated crop-livestock-forest systems

“…As air temperatures approach those of skin temperature, evaporation becomes the major route for heat exchange with the environment (Hansen 2004).This situation was observed in our study, since the average air temperature during the experiment was 32°C, in ICLF and ICL, and skin temperature was 30.6°C and 31.4°C (p > 0,05), in ICLF and ICL respectively. Melo-Costa et al (2018) showed that the energetic costs of the thermoregulation seem to be lower in Nellore animals when compared with other breeds reared in tropical environments. The metabolic heat production, respiratory rate, and cutaneous evaporation were stable in an air temperature range of 24 to 35°C, similar to this study.…”

“…Melo-Costa et al ( 2018 ) showed that the energetic costs of the thermoregulation seem to be lower in Nellore animals when compared with other breeds reared in tropical environments. The metabolic heat production, respiratory rate, and cutaneous evaporation were stable in an air temperature range of 24 to 35 °C, similar to this study.…”

Thermal equilibrium of Nellore cattle in tropical conditions: an investigation of circadian pattern

“…Respiratory parameters as percentage of oxygen (O2; %) , carbon dioxide (CO2; %), water vapor pressure (e{TE}), respiratory rate (RR; breaths min -1 ) and ventilation (VE, L s -1 ) were quantified from a system of indirect calorimetry using a facial mask developed by Innovation group of Animal Biometeorology (INOBIO); furthermore, hair coat surface (TS, °C), skin (TEP, °C), and rectal temperature (TR, °C) were recorded with a thermocouple. Metabolic heat production, sensible heat flow (long wave radiation and surface convection), heat loss from respiratory tract and cutaneous evaporation were determined as described in de Melo Costa et al (2017).…”

“…Low metabolism, hair coat and skin properties explain much of the thermotolerance of zebu cattle when compared with Bos taurus breeds raised in warm climates (Finch et al, 1984;Finch, 1985); however, little is investigated about the mechanisms of the heat and mass transfer in Nellore cattle. Preliminary studies was performed by de Melo Costa et al (2017), determining the thermal equilibrium of these animals during diurnal period protected from direct solar radiation. Findings addressed that physiological responses as metabolism, respiratory rate of Nellore animals were stable over the range of air temperature from 24 to 35 °C.…”

Recent Advances on Early Detection of Heat Strain in Dairy Cows Using Animal-Based Indicators: A Review

“…In addition, although there was no adverse event observed during the study, the need to insert a flexible tube 10 cm deep into the nasal cavity may cause some problems since cattle like to lick noses [126]. A facial mask equipped with an indirect calorimetry system is very important for research purposes due to the ability to measure comprehensive respiratory characteristics, including RR, tidal volume, and the composition of exhaled breath [122]. Recently, an accelerometer-based neck-mounted collar was further developed to measure RR [121].…”