3 research outputs found
A software to estimate heat stress impact on dairy cattle productive performance
ArticleThe aim of this study is to develop a computational tool, based on the Temperature and
Humidity Index value, to characterize the thermal environment in dairy cattle barns and to
evaluate the impact of thermal stress on productive performance. The software for the thermal
environment prediction, and determination of the influence of heat stress on dairy cow
productivity (Ambi + Leite) was developed using the C# programming language in the Microsoft
Visual C# 2010 Express Integrated Development Environment. The following scenario was
considered for the program test: air temperature 32掳C, relative air humidity 70% and milk
production potential in thermoneutrality condition 20 kg cow-1 day-1
. The prediction of the
thermal environment based on the simulated situations indicates that the animals are submitted to
a moderate heat stress condition with THI equal to 82.81. In this condition a decrease of
approximately 26% in milk production and a reduction of 4 kg cow-1 day-1
in food intake was
calculated. In conclusion, the developed software can be a practical tool to assist the producer in
making-decision processes
Alternative form to obtain the black globe temperature from environmental variables
ArticleReaching thermal comfort conditions of animals is essential to improve well-being and
to obtain good productive performance. For that reason, farmers require tools to monitor the
microclimatic situation inside the barn. Black Globe-Humidity Index (BGHI) acts as a producer
management tool, assisting in the management of the thermal environment and in decision
making how protect animals from heat stress. The objective of this work was to develop a
mathematical model to estimate the black globe temperature starting from air temperature,
relative humidity and air velocity. To reach this goal, data of air temperature and humidity were
collected, with the aid of recording sensors. The black globe temperature was measured with a
black copper globe thermometer and the air velocity was monitored with a hot wire anemometer.
Data were analysed using a regression model to predict the black globe temperature as a function
of the other variables monitored. The model was evaluated, based on the significance of the
regression and the regression parameters, and the coefficient of determination (R虏). The model
proved to be adequate for the estimation of the black globe temperature with R2 = 0.9166 and the
regression and its parameters being significant (p < 0.05). The percentage error of the model was
low (approximately 2.2%). In conclusion, a high relation between the data estimated by the model
with the data obtained by the standard black globe thermometer was demonstrated
Computational fluids dynamics (CFD) in the spatial distribution of air velocity in prototype designed for animal experimentation in controlled environments
ArticleMaintaining a comfortable and productive thermal environment is one of the major
challenges of poultry farming in tropical and hot climates. The thermal environment encompasses
a number of factors that interact with each other and reflect the actual thermal sensation of the
animals. These factors characterize the microclimate inside the facilities and influence the
behaviour, performance and well-being of the birds. Thus, the objective of this study is to propose
and validate a computational model of fluid dynamics to evaluate the spatial distribution of air
velocity and the performance of a system designed to control air velocity variation for use in
experiments with birds in controlled environment. The performance of the experimental
ventilation prototype was evaluated based on air velocity distribution profiles in cages. Each
prototype consisted of two fans coupled to a PVC pipe 25 cm in diameter, one at each end of the
pipe, with airflow directed along the entire feeder installed in front of the cages. The contour
conditions considered for the simulation of airflow inside the cage were air temperature of 35 掳C
at the entrance and exit of the cage; air velocity equal to 2.3 m s
-1
at the entrance of the cage;
pressure of 0 Pa. The model proposed in this study was representative when compared to the
experimental measurements, and it can be used in the study of air flow behaviour and distribution
for the improvement of the prototype design for later studies