In this final article of a three-part series on the basic principles of chicken housing, independent poultry consultant Jan Grobbelaar discusses natural and environmentally controlled ventilation.
Two ventilation systems are used in egg and boiler production: natural ventilation (opensided houses), and mechanical ventilation (environmentally controlled houses).
The main difference is the way in which the environment is controlled. In a naturally ventilated house, the inside environment is controlled using natural wind and airflow; in a mechanically ventilated house, electric fans are employed.
NATURAL VENTILATION
In a naturally ventilated poultry house, the key is to maximise the wind; the building should therefore be constructed so that it uses the natural wind to create airflow. This means it should be oriented so that the open sides face the direction of the prevailing wind. The precise angle is not that critical, as effective ventilation occurs up to 30° either side of the wind direction.
(The house should also be as close as possible to an east-west direction lengthwise to minimise direct sunlight into the house.)
Natural ventilation in a building can be created by means of two actions: the stack effect and the wind force (pressure) effect. The ventilation requirements for a naturally ventilated building are expressed in terms of the fresh air exchange rate, which indicates the number of times the volume of air in the building is replaced (volume = wall height x building width x building length). The ventilation system must replace this interior air with fresh air over a specified period. Irrespective of the outside temperature and age of the chickens, ventilation must be sufficient to ensure there is no build-up of stale air in the house.
THE STACK EFFECT
Denne historien er fra June 15, 2018-utgaven av Farmer's Weekly.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent ? Logg på
Denne historien er fra June 15, 2018-utgaven av Farmer's Weekly.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent? Logg på
Syngenta Seedcare celebrates a decade of innovation
Syngenta's ambition is to enable their customers' investments to grow in healthy soil from treated seeds to young plants through innovation and collaboration, writes Magda du Toit.
Agri workers shine at Western Cape awards
Lindie-Alet van Staden, a garden and olive orchard manager at L’Ormarins Wine Estate in Franschhoek, was crowned as the Western Cape Prestige Agri-Worker of 2024 at a gala event recently held near Paarl.
Small and large farmers recognised at grain awards
The annual Grain SA/Syngenta awards ceremony bears testimony to the quality of farmers in the grain industry.
Growing partnerships: Fedgroup's flexible and innovative approach
Janine Ryan spoke to Warren Winchester, general manager of impact investing at Fedgroup, about why the company became involved in agriculture, and what it offers farmers and their immediate communities.
Why fish farms fail, and how to avoid becoming a statistic
The popularity of launching fish farms is not matched by their success. Leslie Ter Morshuizen, owner of Aquaculture Solutions, explores the factors that cause most of these businesses to go under.
Where history and modernity meet in a luxurious setting
Brian Berkman kept his eyes peeled for ghosts in the oldest continuously run hotel in South Africa, but all he found was a fabulous two-night stay.
THE HITCHING POST
I'm a stylish elderly lady with a radiant glow and a good sense of humour that keeps me young at heart.
Cutworms: check the weeds on your fields!
Zunel van Eeden explains why understanding the ecological interplay between cutworms and weeds is crucial for effective pest management. Producers should disrupt the life cycle of cutworms to minimise crop damage.
Does high-density grazing mimic grazing patterns of game?
In their paper on high-density grazing in Southern Africa, professors Angelinus Franke and Elmarie Kotzé from the Department of Soil, Crop and Climate Sciences at the University of the Free State say high-density grazing systems may not accurately reflect natural ecosystems. Roelof Bezuidenhout reports.
Global grain outlook: 2024/25 marketing season
In its latest summer crops report, the Crop Estimates Committee says South African farmers intend to plant 4,47 million hectares of summer grains and oilseeds in the 2024/25 season, up 1% from the previous season. As South Africa exports maize and soya bean, Annelie Coleman reports on the latest trends in the international grain and oilseed markets, amid fluctuations in weather conditions and ongoing armed conflicts.
