Dr Oscar Blanco (BVSc, PhD)

Last month we discussed the second last part of the series, namely ventilation, curtain management and the benefits of temperature record keeping. This month we complete the series by taking a closer look on how to utilise your thermometer and what to look out for when monitoring your chicks for thermal stress.

It is advisable to have at least one thermometer inside the house (or more for bigger houses), always at chicken height. Reading and recording the temperature at least twice a day would be a good practice. Checking the brooding temperature during the night is very relevant, since normally the coldest temperatures are recorded at that time. A step forward will be to place a minimum and maximum thermometer (MMT), which will allow you to know every morning what the minimum and maximum temperatures for the last 24 hours were. The above recommended daily readings can also be done with the same MMT.

The possibilities for recording temperatures are very wide. A daily recording sheet is usually sufficient, however big operations are currently using miniature temperature data loggers. Such devices are able not to only measure temperature, but to also store the records every specified time span (for example every 5 minutes); such information can be downloaded to a personal computer and visualised in the form of graphs. The cost of this technology has dropped in the latest years; however, it may still be a bit too expensive for smaller producers.

Measuring the temperature of the floor may be a bit more complex. The medium to large size enterprises use infrared thermometers, a sort of gun with a beam of infrared light that will return the temperature of the floor when the beam is directed towards it. However, this technology may not be feasible for smaller-scale farmers. Third, measuring cloacal temperature is recommended for the first four to five days. As stated above, values between 39,4°C and 40,5°C are indicative of thermal comfort. The temperature is measured by placing a Braun Thermoscan® thermometer on the opening of the cloaca. This type of thermometer is preferred because of the short time required to perform the readings, however its price can be also too high for smaller enterprises. Although all these records are very useful, the ultimate way to know whether we are doing things properly, is by assessing the behaviour of the chicks.

Check the chickens!

The first thing you need to observe, is the distribution of the birds in the brooding area. If the chicks are huddling too close to the heat source and on top of the tray feeders, you may infer that they feel cold. Alternatively, if they try to keep away from the heat source, moving against the walls of the house or of the brooding ring, it may be because they feel too hot. Non-uniform distributions as well as birds against the walls of the house may indicate cold drafts affecting the birds.

Finally, you may also consider that the combination of air drafts and low temperature may occur. One should aim at having chicks uniformly distributed throughout the brooding area; the birds should be engaged in different activities (for example eating, drinking, resting, et cetera). A high proportion of birds huddling together normally indicates low temperatures. Panting indicates that the temperature is so high that the body temperature of the chicks have exceeded the maximum limit.

The level of noise produced by the birds is also an indication of thermal stress. Normally, birds that are comfortable produce little noise. As the chicks feel colder, more of them start chirping, louder and more frequently. Finally, another quick way to assess whether the chicks are feeling cold, is by placing the birds’ feet on the side of your neck. If the feet feel cold, then the birds most probably are also feeling cold.

Summary

• Newly hatched chicks are unable to maintain their body temperature between the normal limits of 39,6 and 40,5°C. Therefore, they should be put in an environment that minimises heat loss.
• In order to help the birds to maintain their body temperature, warm and properly ventilated environments, as well as dry, warm bedding, should be provided.
• Inappropriate ambient and bedding temperatures have been related to health and performance issues during and after the brooding period.
• It is highly advisable to record air temperatures.
• The best way to know whether the chicks are comfortable, is to observe their distribution in the brooding area and their behaviour.

A rectal thermometer is very popular
since it requires a short time to
give an accurate reading, and it is
inexpensive.