AWS

The ability of cattle to tolerate heat load varies depending on factors such as cattle breed, health status, coat colour, degree of finish, and pen conditions (i.e. whether the pen is shaded or unshaded and the manure management practices employed).

For this reason the threshold at which heat load starts to accumulate also varies depending on these factors. For the purposes of forecasting, various heat load thresholds have been incorporated to account for these factors (for example - AHLU86 and AHLU95 where 86 and 95 are the heat load thresholds upper limit (UL) respectively).

The RAP calculator is used to calculate the HLI threshold to use for your particular operation. If the threshold you calculate for your operation falls between the values utilised in the forecasts, you will have to estimate the results for your situation by interpolating between the forecast values. The RAP also gives an assessment of the risk of heatload events based on the site specific data entered and historical climatic data.

The technical documentation of RAP, including the formulas used in its calculations, can be found here >>

The Heat Load Index (HLI) – has been developed as an indicator of the environmental heat load placed on cattle. There are a number of climatic conditions that may predispose feedlot cattle to high body heat loads, including

• A recent rain event
• A high ongoing minimum and maximum ambient temperature
• A high ongoing relative humidity
• An absence of cloud cover with a high solar radiation level
• Minimal air movement over an extended period (4-5 days)
• A sudden change to adverse climatic conditions

It is usually a combination of some or all of these conditions that leads to an excessive heat load event, which may result in cattle deaths if conditions persist for a number of days. The Heat Load Index (HLI) has been developed as an indicator of the environmental heat load placed on cattle. The interaction and duration of the following meteorological variables contribute to heat stress;

• BGT = Black Globe Temperature (°C)
• RelHum = relative humidity (%)
• WSpeed = wind speed (m/s)

Registration is free and takes only a couple of minutes. If you're not registered click here.

Registered user can login here.

If you would like to register your site to receive a heat load forecast for your feedlot location and/or the new e-mail and/or SMS alert service, register here.

To see a result, select one cattle condition from every dropdown below:

Use the Risk Analysis Program to work out which AHLU applies to your operation.

Calculate your Heat Load Index here

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Further information or assistance is available from:

Forecasting Team @ Katestone

Phone (07) 3369 3699

Katestone are industry leaders in air quality and meteorology services and can advise you on issues that may affect your business, such as odour and dust assessment, air dispersion modelling or even expert witness services.

Katestone experts are experienced with a variety of industries including:

• Intensive agriculture (poultry, piggery, feedlot)
• Utilities (water/wastewater, sewage)
• Food Processing
• Waste management (landfill, composting, incineration)
• Rendering/abattoirs

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