Weight Targets in AgriNet HerdApp
When weighing dairy replacements, HerdApp can tell a farmer if a heifer is under target or over target before the heifer leaves the scales.
HerdApp actually has 2 targets at the moment;
- the initial Breed Target system that we have using successfully for years
- a new EBI Target based on the maintenance value in the EBI.
The Breed Target system allows the farmer to set the target weight at first calving for different breeds. For example, set that you want all FR maiden heifers to calve on 01/02 and calve down at 500 kilos.
HerdApp then uses growth curves to back calculate what weight a maiden heifer should be at different stages from birth to this first calving date. In the example below, HerdApp estimates that the heifer should be 453 kilos of the date of weighing, so it is 9 kilos under the Breed Target.
HerdApp uses different growth curves depending on the month of birth. A heifer born in April has 22 months to calve down in February 2 years later while a heifer born in February has 24 months. The April born heifer needs to grow faster if possible.
In 2021 a new EBI Target was introduced. There is a very strong correlation between the EBI maintenance value and the mature cow weight. HerdApp uses 90% of the EBI estimated mature cow weight to estimate the weight at first calving. The same growth curves are used to estimate the target weight today.
In the example below this EBI Target gives a target value of 436 so according to this calculation the heifer is 8 kilos overweight.
We decided to keep the 2 target systems in place initially to see how the EBI Target value is working on the ground relative to the Breed Target – do farmers trust the targets? The feedback from a good number of HerdApp users is that the EBI Target is very good at predicting target weights.
It greatly helps on making feeding decisions after a batch of heifers have been weighed.
To set the Breed Target, click on the button Target above and the screen below will appear – where you can set the Breed Target for different breeds.