This post is an extract from CEO and Co-Founder, Bill Mitchell’s fortnightly Optiweigh Insights email newsletter. To get a copy in your inbox, SUBSCRIBE HERE.
I had a call from Harry Perrett this week that really got me thinking about this again. Harry is based near Wandoan in QLD and has been getting great results from his two Optiweigh units over the past three and a half years. He finds the weights are always very close to his yard weights so an Optiweigh unit goes in with lead mobs to work out how many are going to be at his target weight for the feedlot and when.
He rang me because this week he got in a mob in to truck, and based on the Optiweigh data he was expecting to have 163 animals above his target weight. However, after weighing them in the yards, before trucking, he only had 66.
The surprising thing was that after a 300km trip, the delivered weight at the feedlot was the same weight as the weight in the yards (both at 471kg). For whatever reason it seems that the cattle were basically ‘empty’ when they came into the yards that day to be sorted and trucked, and hence the discrepancy to the weights in the paddock.
As it turned out, if Harry had just taken the heaviest 163 animals they would have still met his target weight delivered at the feedlot.
I asked my personal assistant (ChatGPT) to do a bit of research on fluctuating full weights due to gut-fill and it came back with this:
Livestock weight readings are influenced by both equipment accuracy and natural biological variation. Well-maintained static platform scales can achieve ±1–2% accuracy. However, day-to-day fluctuations of 3–8% — caused mainly by changes in gut fill, water intake, and waste output — can dwarf these technical margins.
A 500 kg steer, for instance, may vary by 15–30 kg within 24 hours without any real tissue gain or loss. This means even perfectly calibrated scales can give “different” weights from one day to the next.
Standardising weighing time and conditions, and relying on frequent measurements with trend analysis rather than single readings, gives the most reliable picture of true growth.
All this shows that weighing animals is not an exact science. Differences exist between paddock weights, yard weights and delivered weights. And while much of the strength of paddock weighing lies in it’s ability to generate multiple data points day after day, any unexpected discrepancy to yard weights or delivered weights is always going to raise questions.
That is why purchasing an Optiweigh unit comes with backup support. Our dedicated analyst Safina is here to help work through such issues if and when they arise. She also works with our tech team and can run an analysis on your data to give projections for delivered weights or carcass weights based on your Optiweigh weights.
It’s all part of the service so contact me to find out more or get in touch direct with Saf during office hours on 1300 678493 or [email protected].