Last month we looked at the benefits of a warm environment and how your chickens react in less than perfect conditions. This month, we look at different ways to achieve the perfect environment for your chicks.

This article is part of a series. Remember to read Part 1: Thriving in a warm environment

As shown in figure 1, a newly hatched chicken has a small body with a relatively large surface area, and it is poorly insulated by a layer of down feathers. This bird has relatively large, non-insulated feet in constant contact with the floor surface. All this determines a natural tendency of the bird to lose heat to its surroundings.

Additionally, the ability of the bird to regulate its heat exchange with the environment is not developed yet. Consequently, it is impossible for the bird to maintain its body temperature in the normal range (rectal temperature between 39,4 °C and 40,5 °C), unless the environmental conditions are appropriate.

In other words, if we are not able to reduce the heat loss to the environment as mother hen does, then the body temperature of the chicks will be compromised, and their development and liveability will be affected.

Fortunately for us, there are certain techniques that we can apply in order to reduce the heat loss of the birds. First, we need to understand that the heat moves following a difference of temperatures, from the higher to the lower temperature (that explains why, for example, a cake cools down when we take it out of the oven). Since, as we said above, the newly hatched chick cannot control the amount of heat it dissipates, we can decrease the heat lost by placing it in a warm environment (Figure 2).

For Indian River birds (Tiger Chicks breed), the initial combination of ambient temperature and relative humidity (RH) at chicken height that minimises heat loss is 30,8 °C with a 60% RH at day one.

As the chicken grows, it becomes more resistant to heat loss (for example by development of a feather coat) and its ability to regulate heat dissipation increases.

Then, the required ambient temperature gradually drops; normally a reduction of about 0,5 °C per day is recommended, reaching approximately 22,5 °C with 60% RH by day 21. There are many ways of achieving the desired temperatures; in Zambia braziers with charcoal are the most usual heat source, but infrared light are gaining in popularity. Similar principles apply to the heat loss from the feet to the floor (Figures 1 and 2).

Unlike older birds, newly hatched chicks are unable to regulate the amount of blood flowing through their limbs, so a lot of heat could potentially be lost from the feet to a cold floor, cooling down the blood circulating through them. This cooled blood will reduce the body temperature when it returns to the body core.

As said above, we want to avoid body temperature drops during the first weeks but, since Mother Hen is not around, we need to make sure that the heat loss to the floor is reduced by giving the birds well-insulated, warm floors (Figure 2). The floor insulation is increased by placing a layer of a material such as wood-shavings on the floor. This material should be clean and, most of all, dry. High moisture content in the bedding will increase the heat loss to the floor.

Ideally, such a layer should be between five and ten centimetres thick.

Most growers currently use some sort of floor insulation, however the temperature of the floor is usually overlooked. Going back to the principle of heat transfer, higher temperature differences between the feet and the floor will increase the heat loss.

Therefore, to minimise heat loss through the feet, a floor temperature of 28 to 30°C is recommended at day one. It is important to remember that, depending on the properties of the poultry house, it will take a certain time to reach the required temperatures, especially in the floor. Therefore, it is recommended to start heating up the brooding area about 24 hours before the arrival of the chicks.

Remember that, although the birds are not inside yet, the house should be closely watched during pre-heating due to the risk of fire, especially when using braziers with coals as a source of heat. Although providing a warm environment is primordial, it is important to remember that overheating also adversely affects the performance of the chicks. Chickens cannot sweat, so they lose heat by panting. During panting, not only heat is lost, but also water.

Therefore, a direct consequence of birds exposed to very hot brooding temperatures is dehydration. In future articles we shall analyse dehydration and other consequences of very cold and very warm brooding environments in more depth.

Next month, we tackle the ventilation issue by discussing air replacement and curtains.