737 research outputs found
Patterns of silver eel (Anguilla anguilla L.) sex ratio in a catchment
Changes in the numbers and size-class structure of European silver eels, Anguilla anguilla, in the River Fre´mur (France) were examined over a 9-year period after installation of downstream eel passes. The number of silver eels migrating downstream peaked in 1999, then decreased strongly and steadily after 2000, reaching relatively low levels. At the same time, a gradual shift in the silver eel sex ratio from a dominance of males (size from 270 to 442 mm, age from 3 to 6 years) to females (size from 366 to 1112 mm, age from 4 to 9 years) was recorded. Possible explanations for the escapement patterns observed are environmental sex determination and the installation of eel passes on the main hydraulic engineering structures in 1992 and 1996
Analysis of environmental conditions in two different Compost Bedded Pack Barn systems for dairy cattle
Received: February 1st, 2023 ; Accepted: April 27th, 2023 ; Published: May 10th, 2023 ; Correspondence: [email protected], [email protected] objective of this study was to analyse and compare the thermal environment of
dairy cattle facilities in an open compost bedded pack barn (CBP) with natural ventilation and
closed CBP (without thermal insulation) and climate control system. The research was conducted
in a property located in Zona da Mata, Minas Gerais, Brazil. During the summer and for different
periods of the day, the following average environmental variables observed inside the facilities
were measured: dry bulb temperature, relative humidity and Temperature and Humidity Index
(THI). The results were submitted to an analysis of variance to determine the significance of the
variables in the different treatments. It was found that the closed and climate control system CBP
promoted greater control of the facility's internal microclimate, registering smaller thermal
amplitudes and a greater reduction in the animals' exposure time to stressful thermal conditions,
compared to the CBP with natural ventilation. However, during summer afternoons, comfort
indices indicated moderate stress. It is concluded that the closed CBP, regarding the analysed
variables, indicated potential use, provided that a careful study of the climate of the region is
carried out before implementation, the factors related to the ambient conditioning and better
insulation of the construction are adjusted. The climatic variables inside the open CBP indicated
a high stress condition for the animals, suggesting the placement of positive pressure fans and
sprinklers properly distributed in the feed alley, to guarantee benefits to the entire area of the
animal housing
Analysis of environmental conditions and management in a compost-bedded pack barn with tunnel ventilation
Received: January 5th, 2021 ; Accepted: March 27th, 2021 ; Published: April 16th, 2021 ; Correspondence: [email protected] housing system based on compost-bedded pack for dairy cows is spreading rapidly
in Brazil. Completely open buildings without curtains and simple roofs are usually provided.
However, in the last years some new completely closed barns have been realized. This study aims
to analyse one of these closed barns, located in the State of Minas Gerais. The two main sides of
the facility are provided with polyethylene curtains of blue colour and five deflectors. The barn
is equipped with an evaporative adiabatic cooling system, associated with the tunnel-style
ventilation, realized with exhaust fans, continuously operating 24 hours a day. 85 lactating
Holstein cows were housed in the barn during the trials carried out in the winter season 2019.
Microclimatic data were collected continuously. Air speed, illuminance and bedding temperature
were measured during the farm visits. Pack moisture was calculated. The results state the
importance of bedding management and climatic conditions inside the barn. It emerges that the
cows housed in this kind of closed barn, with forced ventilation, are in good thermal conditions,
which are fairly constant. The average illumination of the barn can be considered acceptable
(55.06 lx), even if some areas of the barn present values below the minimum ones reported in
literature. The bedding temperature varies between a maximum of 36.33 °C and a minimum of
25.44 °C with an average of 31.26 °C. The values of bedding moisture are between a maximum
of 64.36% and a minimum of 60.81% with an average of 62.48%
Effect of environmental temperature during the of brooding period on growing period of pullets viscera and tibia
ArticlePoultry production in subtropical and tropical regions faces many problems, one of
which is the high air temperature causing thermal stress, particularly dangerous in high-producing
birds. Thus, the negative effects caused by heat stress (HS) must be managed. The objective of
this study was to evaluate the effects of four different levels of HS in viscera and tibia of pullets.
A total of 648 chicks (Lohmann LSL Lite) were used in this study in two different phases. The
pre-experimental phase (PEP) was from day 1 through 6 weeks of age. The birds were reared
with three different environmental temperatures: thermal comfort, hot and cold. The experimental
phase (EP) was conducted from the 7th to the 17th week. Pullets from each thermal environment
of the PEP were submitted to: 20 °C, 25 °C, 30 °C, 35 °C. At the end of the 17th week of age 120
pullets were euthanatized and the organs, heart, liver, spleen and gizzard were weighed, as also
their tibias. Effects of PEP, and its interaction with EP, were not significant (P < 0.05) for viscera
and tibia weight. However, a significant increase (P < 0.05) in heart weight with the decrease of
the environmental temperature was observed, being the pullets subject to 20ºC and 25 °C with
the heaviest weights. For the liver, pullets subject to the 35 °C had the lowest weight and were
different (P < 0.05) from the other three treatments. For gizzard, the difference (P < 0.05) was
between the treatments 20ºC and 35 °C. These results indicate that brooding temperatures tested
during the first 6 weeks of life did not affect the viscera and bone weight during the growing
phase
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 (R²). 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
Energetic analysis in compost dairy barn: a case study in southeastern Brazil
Received: February 2nd, 2023 ; Accepted: March 25th, 2023 ; Published: August 16th, 2023 ; Correspondence: [email protected], [email protected] efficiency aims to optimize the energy consumption of the processes, activities,
and machinery of the farm, ensuring the comfort, handling, and safety of the animals. The purpose
of the study was to identify the energy consumption demanded by the activities performed at the
Compost Dairy Barn facility, located in Itaguara, Minas Gerais, Brazil and to propose energysaving alternatives, applying the Energy Audit Methodology described by the Institute for Energy
Diversification and Saving (IDAE in Spanish) from Spain. The energy assessment at the facility
allowed us to recognize unnecessary energy expenses in machinery uses, variations in milk
production in relation to environmental conditions, waste disposal, and to propose improvement
alternatives to reduce energy consumption expenses. Waste production data of 1577.7 kg per year
was obtained, which corresponds to the bedding and feeding areas, and 175 kg of waste for the
feeding area. Data on the temperature and humidity of the bedding area were collected to
determine which of the five months of research is the most demanding in terms of energy. To
maintain the animal’s welfare, tracing the times of substantial use of machinery (e.g., fans,
tractors) at the facility and calculating Equivalent Temperature Index (ETI) was necessary. The
highest percentage consumption of energy was represented by tractors in bedding maintenance
and supply, by around 95.03%. The energy analysis of the farm showed a reduction in energy
consumption of 45.03%, compared to the initial consumption percentages of the overall livestock
activity
Variable velocity system for evaluating effects of air velocity on Japanese quail
This study documents the design and performance of a system to apply different
magnitudes of air velocity to Japanese quail, to evaluate the combined effects of velocity,
temperature and humidity on bird behaviour, performance and welfare. The system was
developed to simulate observed field conditions ocurring in regions with high winds where quail
are raised in curtain-sided housing. System performance consisted of characterizing air velocity
distribution in cages downstream of the air velocity which was directed at the front of the cages.
The system consisted of two fans attached to a 25 cm PVC tube, one at each end, with the outlet
airflow directed through a continuous slot over the cage front at the feeder. The design and
performance of this experimental system was evaluated, with six such systems were built and
utilized in research trials. To assess system performance, air velocity was measured at 275 points
per cage uniformly arranged along the three dimensions (length, width and height) in eight cages
with zero, 1, 2 or 3 m s-1 nominal velocity setpoints. Spatial distribution of velocity was analysed
by mapping and from descriptive statistics, with attention to the zone closest to the feeder where
birds must go to eat. There was no significant difference (P > 0.05) found in mean paired
difference of air speed data measured for pairs of front portion cages with similar velocities. A
significant positive correlation was found (P < 0.001) between the measured air velocity at paired
points in the cages subjected to the same velocity treatment. A comparison of measured mean air
velocity to the nominal setpoint values used for experiments indicated that careful attention to
outlet adjustment is important, especially at higher nominal velocity setpoint as 3 (± 0.10) m s-1
which was difficult to achieve with the system. An example of the use of the deployment of the
variable velocity system in controlled environment chambers with Japanese quail is provided
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 °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
Antitumoral, antileishmanial and antimalarial activity of pentacyclic 1,4-naphthoquinone derivatives
Pterocarpanquinones 8a-c, previously synthesized in our laboratory, and an homologous series of derivatives, compounds 9a-c prepared in this work, were evaluated on breast cancer cells (MCF-7) and on the parasites Leishmania amazonensis and Plasmodium falciparum, in culture. Compounds 8a-c were more potent than 9a-c on tumor cells and Leishmania amazonensis. On the other hand, 9a-c showed to be more active on Plasmodium falciparum. All the compounds studied were bioselective, presenting negligible cytotoxicity against fresh murine lymphocytes and human lymphocytes activated by the mitogen phytohemaglutinin (PHA)
Analysing livestock network data for infectious disease control: an argument for routine data collection in emerging economies
Livestock movements are an important mechanism of infectious disease transmission. Where these are well recorded, network analysis tools have been used to successfully identify system properties, highlight vulnerabilities to transmission, and inform targeted surveillance and control. Here we highlight the main uses of network properties in understanding livestock disease epidemiology and discuss statistical approaches to infer network characteristics from biased or fragmented datasets. We use a ‘hurdle model’ approach that predicts (i) the probability of movement and (ii) the number of livestock moved to generate synthetic ‘complete’ networks of movements between administrative wards, exploiting routinely collected government movement permit data from northern Tanzania. We demonstrate that this model captures a significant amount of the observed variation. Combining the cattle movement network with a spatial between-ward contact layer, we create a multiplex, over which we simulated the spread of ‘fast’ (R0 = 3) and ‘slow’ (R0 = 1.5) pathogens, and assess the effects of random versus targeted disease control interventions (vaccination and movement ban). The targeted interventions substantially outperform those randomly implemented for both fast and slow pathogens. Our findings provide motivation to encourage routine collection and centralization of movement data to construct representative networks.
This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’. This theme issue is linked with the earlier issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’
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