HOW TO ACHIEVE GENETIC GAIN
The purchase and introduction of superior bulls is one of the quickest ways to achieve genetic change in a herd. The effect of bull selection will persist in the herd for generations to come.
USEFUL LINKS
To really understand EBVs, Indexes and how to use them for selection we recommend you visit
CODE OF STANDARDSWhen sourcing a bull, it is advisable to buy from a similar or superior herd in both management and performance. Having found such herds, always take into consideration breeding goals, selection criteria, traits of economic importance, market requirements, herd production targets and current herd performance.”
(FUTURE BEEF, 2020)
ESTIMATED BREEDING VALUES (EBVs)
To describe the genetic merit of an animal for economically important traits, we use EBVs.
We understand that EBVs provide a basis for comparing the genetic merit of potential selection candidates, and that the genes an individual passes on to their progeny will, on average, be 50% of their own EBV for any given trait. If, for example, we wanted to compare the genetic merit of two bulls’ progeny for 600 day weight (one bull having an EBV of +50 and the other 0), we can estimate that the progeny of the first bull will be 25kg heavier at 600 days old than the progeny of the second.
EBVs EXPLAINED
EBVs are also displayed in an EBV Percentile Graph (as above) that can be very useful for a quick visual on where that animal sits (percentile band for each trait/Index).
Bars to the right of the middle identify traits which are better than breed average for a given trait or $Index. In general, the further the line is to the right, the better. However, for some traits (such as mature cow weight or milk), this is open to breeder discretion, where selecting to an optimum may be more suited to their breeding objectives.
Bars to the left of the middle indicate that the EBV/ Index is below breed average, and in general, the further the line is to the left, the worse, though the same caveats around optimal selection may apply for some traits (lower than breed average genetic mature cow weight or MILK, for example, MAY be appropriate for some breeding objectives).
EBV ACCURACY
Each EBV will be presented with an accuracy (%). This number describes the degree to which an EBV may change, as new information on an individual, its progeny or relatives becomes available. Decisions around EBV accuracy are essentially ones of risk management. For a highly accurate bull, we are confident that the EBVs accurately describe the genetics he will pass on to his progeny. For a less accurate animal, the chance that their EBV will go up or down is greater, as more information becomes available. Two key points about EBV accuracy are:
1. In almost every case, a change in an EBV will be associated with an INCREASE in accuracy.
2. The risks associated with lower EBV accuracies (in young bulls for example) can be largely negated by using numbers of bulls in that accuracy range, with the expectation that any changes in EBV will cancel each other out across numbers of animals.
SELECTION INDEXES
EBVs are a great tool for helping in bull selection for individual traits. We all know, however, there is often more than single traits we would like to select for, and that selection pressure applied to some traits can produce correlated responses in others. This is where Indexes can be helpful. Indexes have been created to describe genetic profitability for specific Brahman production system and market combinations. Selection indexes are calculated based on economically based weightings for each trait in the Brahman BREEDPLAN evaluation and are a relatively simple means of identifying potential selection candidates which will suit your breeding objective.
- Live Export Index
- Central Production Index
To understand these and how they might apply to you click here