In modern hatcheries, climate data are collected from various sensors installed in incubators and hatchery rooms and from handheld measuring instruments. The performance of the sensors is crucial for continuous production of batches of first-class day-old chicks, Marleen Boerjan, academy director with Pas Reform Hatchery Technologies, said in a white paper.
Maintenance of sensors — including cleaning filters and calibration — is of great importance, Boerjan said, explaining that calibration means comparing readouts from the sensor with readouts from a certified standard.
As long as hatchability and chick quality meet expectations, hatchery managers can rely on their team for maintenance and sensor calibration, she said, but to be able to interpret data correctly, the hatchery manager needs information on data collection procedures and on the level of reliability of the data delivered.
According to Boerjan, some standard information is required for data interpretation, such as:
- Sensor accuracy is reflected in the "quality" of the data measured. Accuracy is an expression of the difference (error) between the measured value and the true value. Since the "true value" cannot be known precisely, accuracy is presented as a range of values.
- Precision, or repeatability, is a value ascribed to a sensor that describes the spread in data on a standard object measured under standardized conditions. In practice, this means that managers calculate, for example, the average and standard deviation of eggshell temperature (n = 10) of one egg measured with an infrared ear thermometer. To do so, at least 10 measurements must be taken from the same spot on the eggshell.
- Random errors occur and may be due to precision limitations of the instruments or conditions not being standardized throughout measurement.
- A stable sensor remains constant over time or shows low drift as it ages.
- A sensor is calibrated if its readouts have been compared, under similar conditions, to readouts from a standard sensor whose accuracy is 10 times higher. The standard sensor has a certificate of calibration provided by an institution that is certified to calibrate sensors and instruments.
- Reference values (or ranges of values) are numerical data collected under normal/standard conditions and measured using calibrated sensors of known precision and stability. Reference data can be (1) determined (mean + standard deviation) from climate data collected in the hatchery or (2) provided by breeder companies, such as average eggshell temperatures for incubation or set points for relative humidity to achieve optimum hatchability and chick quality.
Boerjan concluded that a stable sensor of high repeatability is the best choice if a hatchery manager needs to collect reliable data on a routine basis. Sensors must be calibrated regularly by a certified institution. A sensor or measuring instrument must be replaced if its deviation from the calibrated sensor is unacceptable (as defined by hatchery management).
Boerjan also provided the following points:
- Clean sensors and protection filters before taking measurements.
- Realize that accurate and stable instruments are essential if your aim is to perform a statistical analysis of data collected over longer periods.
- Contact your incubator supplier for advice on how to maintain and calibrate incubator sensors.
- Ensure that a certified institution calibrates your sensor and measuring instruments regularly.
- Be aware that the readout from your reliable instrument may differ from readouts from other brands of instruments, such as those used by colleague hatchery managers, for example. Instruments with high levels of accuracy deliver readouts that can be shared and compared among hatchery managers.