Hot Cows


One way to ensure that the steak on your plate looks like the picture in the menu is to put the cattle on a controlled diet. So cattle are ‘finished off’ in feedlots, where they dine on grains and supplements.

One of the challenges faced by cattle on feedlots is heat stress. Under certain conditions heat can accumulate in the animals faster that they can dissipate it. If this just resulted in shorter cooking times everyone would think it a good thing - with the possible exception of the cows - but it’s stressful for the animals and lowers productivity in the feedlots. So it’s a pretty important thing for feedlot managers to be able to track.

There are a couple of important concepts here. The first is Heat Load Index, or HLI. This is calculated from black globe temperature (a better reference point than ambient air temperature when it comes to representing heat in an animal), wind speed and relative humidity. In short, the higher the radiant heat energy load, temperature and humidity and the lower the wind speed, the more likely it is that cattle will experience heat stress.

The next important concept is Accumulated Heat Load Units, or AHLU. This represents the cumulative effect of heat stress on animals and takes into account the breed type, pen conditions and the persistence of the conditions that cause heat stress.

The easiest way to monitor these conditions is to use a purpose-built weather station such as our Feedlot Weather Station. Because we think cows should only do their sizzling on a hot plate.

Feedlot Weather Station at Gunnee in New South Wales
Feedlot Weather Station at Gunnee in New South Wales



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