A percentile for each trait is calculated for all animals in the TransTasman Angus Cattle Evaluation and is the rank of where each Estimated Breeding Value (EBV) sits in reference to the rest of the population. Notably, the population is benchmarked against the 2-year-old animals in the population. This is important as most breeds and breed societies have experienced significant changes in their genetic merit when compared to their historical genetic level (i.e. their genetic base) for most traits. Percentiles cannot be compared across different benchmarked populations, such as different breeds or same breeds but different populations (e.g. the Australian Angus population and the New Zealand or American Angus populations).
Using the percentile to compare each EBV against the breed average allows you to quickly identify exactly where an animal ranks within the population for each trait. Click Here to view the most current version of the TransTasman Angus Cattle Evaluation EBV Reference Table.
Using the demonstration animal, the EBV table below (figure 1.) indicates that this animal, with a 200 Day Weight EBV of +58 kg, ranks in the highest 15% of the population for growth at 200 days.
An alternative tool to compare an animal’s EBVs percentile to the current to the population is to use the EBV Percentile Graph (Figure 2.). This graph provides a visual representation of where an animal’s EBVs rank within the population for each trait. The EBV Percentile Graph (figure 2.) shown below also indicates that this animal, with a 200 Day Weight EBV of +58 kg, ranks in the Top 15% of the population for growth at 200 days. Importantly, the centre (50th percentile) of the graph indicates the breed average for the 2-year-old animals of the population.
It is important to note that while for the majority of EBVs it is generally considered more desirable to rank higher in the percentile (i.e. on the right-hand side of the graph), this is not always the case. importantly, the optimum EBVs will depend on your individual breeding objective(s), and the direction in which you are trying to move the genetic level of your own herd. For example, a higher percentile for Mature Cow Weight indicates heavier cows at 5 years of age due to genetics. For those producers trying to moderate the mature cow weight of their herd, this may not be desirable.