Weather station accuracy critical

With summer temperatures starting to ramp up, Meat & Livestock Australia (MLA) is reminding feedlot managers to check the accuracy and location of on-site weather stations as a critical part of their heat load management strategy.

Heat load forecasting services such as the Cattle Heat Load Toolbox, managed by Katestone - http://chlt.katestone.com.au/ - are important management tools to help feedlot managers prepare for impending and occurring heat load events.

However, MLA Feedlot Project Manager, Dr Joe McMeniman, said it was important to note that the heat load model was not developed to precisely predict cattle responses to every heat load event for every type of weather, animal and management condition.

“Forecasting services should be used in conjunction with on-feedlot daily monitoring of the physical responses of the cattle and weather conditions, where an automatic weather station is located on-site,” Dr McMeniman said.

“MLA, in consultation with the Australian Lot Feeders’ Association (ALFA), recently completed a review of heat load forecasting. A key recommendation from the review was the need for improved weather station quality assurance to ensure data integrity in heat load modelling.

“If the quality of data - temperature, humidity, wind speed and solar radiation - feeding into the heat load model is inaccurate, the outputs from the model, such as the Heat Load Index and Accumulated Heat Load Units, will be inaccurate.”

To maintain the integrity of data from automatic weather stations, it is recommended that:

• An appropriate make and model of automatic weather station be purchased, containing a true black globe temperature sensor (bulb)
• Weather stations should be serviced pre-summer by the weather station supplier on an annual basis. Sensors are particularly susceptible to feedlot dust. Certified technicians can provide lot feeders with recommendations on ways to check sensor accuracy with separate measurement devices 
• Weather station data should be monitored every day over summer to detect abnormalities in readings. Lot feeders should ask themselves ‘is the data-stream normal?’ For example, excessively high or low wind speed or humidity. Errors indicate the weather station needs to be formally serviced.
• Weather stations should be appropriately located on earth or unwatered grass and not concrete or asphalt. It is important to ensure readings are not obstructed or biased by shade, topography, buildings, concrete slabs or asphalt roads.

MLA has published a Tips and Tools booklet on weather station siting. To download a copy, visit: http://www.mla.com.au/research-and-development/feeding-finishing-nutrition/Lotfeeding-intensive-finishing/heat-stress/