The use of Thermometer is very essential for the regulation of heat for the chicks. The temperature required is measured at the edge of brooder box while bulbs are placed lower at the level of chicks back.
However, the temperature should not exceed 35ºc during the first and second weeks respectively. It is save to continue heating until the sixth week and heating should be put off when the day is hot.
Chickens are homeotherm, which means that within limits, they can regulate their own body temperature, much as mammals do. However, they are not born that way.
During the embryonic phase, chickens are poikilotherm, which means that their body temperature follows that of their environment, as in reptiles. The difference with reptiles is that they can function properly at a wide range of body temperatures: they simply adjust their metabolism to it.
Chickens achieve ideal development at optimum body temperature, but in the poikilotherm stage they cannot maintain that temperature themselves.
A hatched chick cannot maintain a proper body temperature without your help. Exposing a chick to cool temperatures in the first three weeks of life makes the bird uncomfortable and less likely to eat the feed and drink the water needed for a good start.
In meat-type chickens, cool temperatures can lead to permanent heart damage. Exposing the young bird to cool (20ºC or 70ºF) for the first day or two on the farm can cause the bird to die from heart problems later. Heated premises are definitely needed for brooding.
For small flocks, the most common source of heat is a heat lamp. These lamps accommodate a 250-watt red or clear bulb. When suspended 45 to 60 cm (18 to 24″) off the floor, they provide enough heat to brood up to 100 chicks for a single-light, or 300 to 500 for a four-light model.
Some units have thermostatic controls, while others have to be raised or lowered to provide the required temperature at bird level. As the birds grow older, lower the temperature by raising the heat lamp or reducing the wattage of the bulbs.
Turn the heat on at least one day before the birds arrive on the farm. The temperature 1 cm (½ “) below the litter surface should be at least 26ºC (80ºF). Even if the air is the correct temperature, the birds can be chilled by the cold floor under them.
Read Also: Proper Poultry Litter Management
Temperature on the floor, at the edge of the heat source, should be 32 to 35°C (90 to 95°F) for the first week. As long as the temperature at the edge of the heat lamp or brooder stove is this warm, the air temperature 2m (6′) away from the heat source can be as low as 28°C (82°F).
The birds can then chose where they feel most comfortable. If you cannot maintain a hot point next to the heat lamp, an average air temperature of 30 to 31°C (85 to 88°F) is suggested.
The temperature should be reduced by 3°C (5°F) per week, until the room temperature of 20ºC (70ºF) is reached. After six weeks of age, temperatures in the 18 to 21°C (65 to 70°F) range are desirable.
Some hatcheries will sell a 30 to 45cm (12 to 18″) high corrugated cardboard that can be used to set up a brooder that forms a circle around the heat lamp. The ring helps protect the birds from drafts and piling in corners. For 300 birds, you might use a ring 3m (10′) in diameter.
The following tables below are the temperatures required for the chicks:
The number of birds in the brooder house will determine the number of bulbs required and heat should be reduced as the chicks advance in age:
Number of Bulbs required
1 Bulb (60 watts)
2 Bulbs (60 watts)
3 Bulbs (60 watts)
4 Bulbs (60 watts)
5 Bulbs (60 watts)
The critical transition time
For the embryo, the process of changing from poikilotherm to homeotherm takes five or six days – starting at day 19 of incubation and completing when the chick is four to five days old. In chicks from young breeder flocks, this process can take 24 to 48 hours longer.
It actually means that day-old chicks’ ability to regulate or maintain its temperature is as immature as an embryo’s, and if conditions are not optimal, its body temperature can drop dramatically.
Within two hours following placement, a day-old chick’s body temperature can drop more then 5°C, from the optimal level of 40°C to 35°C or lower. In some circumstances body temperatures as low as 33°C have been found, without the bird actually dying – at least not immediately.
We control the body temperature of a day-old chick mainly by controlling heat loss through the floor. If the house is on temperature but the floor is too cold (below 29-30°C), the birds lose too much heat through their feet, lie down and become even colder because now a larger body area is touching the floor, and their body temperature will drop very quickly.
It is clear, therefore, that maintaining the correct air temperature is not enough to prevent this heat loss: it’s exactly the same principle as when we as humans walk barefoot over a cold floor.
Consequences of the Thermometer measuring low temperature
The consequences of this drop in body temperature are quite dramatic. Although day-old chicks are able to deal with a relatively large range of body temperatures, as are all newborn animals, they will – if the correct body temperature is not restored quickly – experience difficulties.
The first reaction of the chick will be to start making noise, to attract the attention of mother hen and to tell her that it needs support. If, in our chicken houses, mother hen doesn’t respond and the temperature drops further, the bird will become under-cooled and start to lie down, which further accelerates the process of becoming under-cooled.
An under-cooled bird will experience stress, which prevents its immune-system from functioning properly, leaving it more susceptible to e-coli or any other type of bacterial infection. In these circumstances, first week mortality will inevitably be increased.
By lying down, the chick will also not find feed and water, as in a normal process it “stumbles” into it when moving around. These “non-starters” will not digest any feed in that first hours/days, so they will also not obtain any heat from the digestion process.
By not eating, the digestive tract is not stimulated, and the immune-system is not stimulated either. When the birds don’t eat, they don’t take up carbohydrates, and these carbohydrates are needed to absorb the yolk residue.
Without eating, the residual yolk will remain longer in the body cavity, increasing the risk of navel-yolk sac mortality. And in this yolk, mother hen stored her maternal anti-bodies.
If the chick is unable to take up the yolk properly because it lacks the carbohydrate energy produced by eating, it will also have reduced access to the benefits of these maternal antibodies.
Last but not least, the consequences for the performance of the flock are significant. The problem is not so much increased mortality in the first week, which although regrettable, is a relatively inexpensive mortality.
However the birds that were under-cooled but didn’t die are more of a concern. These birds will not start for a couple of days, and remain at hatch weight when the rest of the flock is already up to a body weight of 120-150g.
Not only will this variance reduce the flock’s average bodyweight and FCR at seven days of age, but it will also undermine uniformity, both at seven days and at the end. This uniformity shows as uniformity of bodyweight, but can for instance also be expressed as uniformity of immune competency.
Temperature fluctuation at vaccination
Chick sensitivity to temperature fluctuations may significantly influence the effectiveness of day old spray vaccination, performed either in the hatchery or after arrival in the house.
Using an excessive volume of water for vaccine preparation and improper size of droplets are the most common reasons for post vaccination reactions and problems, even if the type of vaccine used was mild enough and correct.
The evaporative effect when a vaccine solution is sprayed can have an undesirable chilling effect, especially when chick holding environments are not organised properly.
Draughts and improperly managed environmental temperatures can exacerbate the discomfort of vaccinated chicks: they are chilled as easily as we are, if we don’t dry our bodies after taking a shower!
In fact it is surprising how remarkable the economic impact of thermal discomfort at an early age can be, when we chill chicks not fully able to maintain their body temperature.
In these flocks, mortality usually starts at three-five days of age; sneezing and rales can occur as early as 48 hours after improper vaccination and often causes too high a condemnation rate.
Thermal stress at early age and immunosupression as a consequence of stress, can also lead to acute or chronic septicaemia (bacteria present in the blood flow) or even viral infections of respiratory system.
Inappropriate spray particle size is less likely to be the only reason for post-vaccination reactions and problems than it is commonly believed to be. In most cases, the actual reason is a combination of size and uneven distribution of droplets combined with environmental factors, which lead to the chilling effect in vaccinated chicks.