Incubating by manual egg shell temperature measurements
Temperature is the most important incubation parameter, and allowing the egg shell temperature to dictate the air temperature during incubation is without a doubt an excellent method of operation. In hatcheries operating with S-line machines, Petersime’s OvoScan™ automatically and precisely makes the necessary egg shell temperature measurements, calculations, and adaptations, without opening the incubator’s doors. If OvoScan™ is not an option in your hatchery, you can manually measure the egg shell temperatures as an alternative. Read how to do this with optimal results and minimal damage to the embryos.
by Roger Banwell, Hatchery Development Manager
Automatic egg shell temperature measurements with OvoScan™
For hatcheries equipped with Petersime S-line incubators, the OvoScan™ system is the optimal solution. It operates in real-time throughout the incubation cycle, constantly taking samples and reacting in 0.1ºF steps in order to precisely maintain the desired shell temperature.
OvoScan™ consists of a set of infrared egg shell scanning units and an intelligent controller holding the OvoScan™ algorithms. Typically, three egg shell scanning units are installed in one incubator. They are positioned on three different locations on a trolley so as to provide a large sample reading.Each egg shell scanner uses infrared sensors to capture the exact temperature of the shells of the eggs in four adjacent positions. The infrared sensor beams are focused to ensure that the temperature measurements are not influenced by the egg’s internal air cell. This technology allows OvoScan™ to take accurate temperature readings regardless of egg size. Moreover, the algorithms implemented in the controller account for expected temperature boundaries and will compensate for infertile eggs, if present. This guarantees error-free measurements in all circumstances.
Manual egg shell temperature measurements
The potential of operating with egg shell temperature measurements has now been accepted within the industry and non-S-line hatcheries are increasingly using handheld infrared thermometers in an attempt to replicate the OvoScan™ system.
Although these manual egg shell temperature measurements can never be done with the same accuracy and ease of use as with OvoScan™, it is an acceptable alternative if done in a controlled way and with accurate equipment. Below, we list some dos and don’ts for incubation by manual egg shell temperature measurements.
The incubator should be loaded in a balanced way (see article Balanced loading of the setter). An extreme mix of flock types, ages, storage times, etc. will make it virtually impossible to identify an average environmental condition that satisfies all the eggs.
Use only suitable infrared thermometers that are well maintained and regularly checked. There are many infrared thermometers on the market today but few are adequate for this procedure. Even many medical thermometers are not suitable for incubator ambient conditions and are not calibrated for the emissivity of an egg surface.
It is not ideal to either constantly open the door of an incubator or leave the door open for extended periods of time. However, short momentary checks at occasional critical periods will not have a detrimental effect. With this in mind, it is important to identify sample points (both in terms of trays and trolleys) that are representative of the average conditions and are easy to access. Choose high, mid and low sample points and note the high, low and average readings.
Always ensure your measuring point is at the equator of the egg, as readings at the air cell or at the bottom of the egg will be misleading.
When to take samples
The main objective of the readings is to prevent temperatures to become dangerously high, but without constantly opening the incubator door in order to take excessively frequent readings. Sample times should be at critical stages during the incubation cycle. Taking into account that the period of embryonic growth (days 9-18) is more critical than the embryonic development period (days 0-9), a suggested routine would be days 3, 6, 9, 11 and daily from this point onwards until transfer.
Make sure your sampling duration is as short as possible. In order to take readings the trolleys will be levelled and the doors opened, and in most cases the air circulating fan will stop. Shown below is a recording of the effect on four eggs spread across one tray at the midpoint of a trolley after 15 days and 18 hours of incubation.
The graph shows how levelling the trolleys widens the temperature bandwidth to almost 0.5⁰F. Opening the door and stopping the fan takes the bandwidth to beyond 1.0⁰F, with some eggs nearing 101.0⁰F. The eggs in this example are not at peak heat production and therefore this cannot be considered worst case scenario.
Interpreting the readings
- Be aware that a low temperature may indicate infertility.
- Always take into account the effects of levelling the trolleys and opening the doors. Especially during the exothermic phase manual measurements will be slightly higher than measurements taken in the airflow inside a working incubator.
- Never make changes in air temperatures greater than 0.2-0.3⁰F at a time. If more is required, make several steps over a few hours.