Dr Oscar Blanco (BVSc, PhD)
Last month we looked at measures to create the perfect temperature environment for our chicks. This month we discuss the second-last part of the series, namely ventilation, curtain management and the benefits of temperature record keeping.
What about ventilation?
A factor also affecting temperature control in chicken houses is ventilation. Ventilation is necessary to reduce the levels of harmful gases that accumulate inside the house and to keep the humidity of the air and of the litter within acceptable limits. Such gases can either come directly from the chickens (carbon dioxide, CO2, for example), be the product of the combustion of fuel used to heat up the house (carbon dioxide, CO2, and carbon monoxide, CO), or be produced by the bacterial activity in the litter (ammonia). However, as we ventilate the brooding area, warm air escapes and colder air enters the house, which may become an issue when trying to control the temperature around the chickens, especially during winter.
The secret is to find a balance between air replacement and temperature control. In naturally ventilated houses, which are the norm in Zambia, this can be achieved by proper curtain management. Although ventilation during brooding deserves an article in itself, it is discussed briefly in this section.
Perhaps the main concept to keep in mind is that cold air tends to sink to the bottom of the house, whilst warm air tends to raise towards the ceiling. Consequently, in order to get rid of the gases without affecting the immediate environment of the birds too much, it is necessary to have the air inlet far above the chickens. How can we achieve that? By using curtains that open from the top towards the bottom instead of from the bottom to the top (as often encountered at Zambian farms).
Curtains opening from the bottom to the top will allow the cold air to drop directly onto the birds, disrupting all our efforts to keep a warm environment around them. This results in increased heat loss from the chicks to the environment. The small birds will try to reduce the exposure to the cold air drafts by huddling against the walls and around the heat sources, spending less time eating.
Having curtains that open in the correct way are not sufficient on it’s own; those curtains should not have holes. Furthermore, leakages around the curtains and through cracks in the walls should also be avoided. This is because the cold air passing through such holes will cause cold spots around the house, also negatively affecting our ability to control the temperature around the birds.
Assessing the environment
How do we know that we are providing the chickens with a favourable environment? How do we know that the chickens are at the correct temperature and that we are doing a good job balancing heating and ventilation? Measuring and recording ambient temperature is a basic and very important tool for many reasons. First, having at least one thermometer inside the house will give you an idea of whether the temperature in the brooding area is acceptable and, if not, it will help you to take action in order to improve the environmental conditions.
Second, having a thermal history of the flock will help you to know what has gone wrong and what to expect from that flock in terms of future performance.
Third, and perhaps not so specifically related to brooding, ambient temperature records give very important information to the veterinarian when trying to investigate a disease or condition affecting a flock. These records could also help you to understand how a facility behaves year after year under different environmental conditions, giving you an idea of what to expect from chickens raised in that house during a given season.
Finally, thermal records may help you to evaluate the impact that any modifications to the facility had on the environmental conditions inside the building.
Next month we shall take a closer look at how to utilise your thermometer and what to look out for when monitoring your chicks.