WHO’S YOUR DADDY?
Registering Calves from Multiple Sire Joinings Ashleigh Horne, Project Officer, Angus Breedplan
There has been an increasing number of Angus Australia members utilising multiple sire joining, where several bulls are joined to a mob of females at the same time, followed by the utilisation of DNA technology to assign the individual sire of calves.
GeneProb Calculations An example is provided below as to what can happen within the GeneProb analysis when the wrong sire is listed in a calf’s pedigree.
While this has a number of management advantages, there are a few key considerations that members must be aware of when registering calves arising from a multiple sire joining.
The calf, ABCN1, has been tested and has been identified as a carrier of DD (i.e. DDC). The calf’s dam, ABCF2, has not been tested for DD, but is expected to be free (i.e. DDFU) based on the tests that have been undertaken on animal’s in her pedigree.
In particular, some members have elected to assign an individual sire from the multiple sire group when registering calves, and then amend the sire later following a DNA parentage verification test. In the long run, this might work, but short term, registering calves with a potentially incorrect sire, causes serious complications.
In scenario 1, the calf has been registered with an incorrect sire, ABCG12, who has previously been identified as being free of DD (i.e. DDF). As the sire has been tested free, and the calf is a carrier, GeneProb assumes that the calf’s dam (who is untested) must actually be a carrier of DD.
Implications of guessing and fixing it later. Angus Australia runs specific analyses that provide our members and the broader public with valuable information about each registered animal. These include the Angus BREEDPLAN analysis which produces estimates of the genetic merit of each animal, and GeneProb which calculates the percentage chance that each animal carries specific genetic abnormalities such as AM, NH, CA and DD.
GeneProb consequently assigns the dam with a 99% chance of being a DD carrier, and assigns each of her relatives (both pedigree and progeny) a probability of being a DD carrier based on their relationship to her.
Both Angus BREEDPLAN and GeneProb rely on pedigree integrity to calculate their respective estimations and probabilities. Obviously, no matter how many checks and balances are put in place, there is always the possibility that an animal may have an incorrect assignment somewhere in the pedigree. However, the more animals that have pedigree integrity issues, the harder it is for both BREEDPLAN and GeneProb to calculate accurate results. Figure 1: Incorrect Sire Assignment
PAge 44
Angus Bulletin — spring 2017