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It’s a very fair question given the cost & hassle of taking a DNA sample and sending it off to a lab to get a bull genotyped. What difference will it actually make?

Quick recap

Genotyping is the process of determining differences in the genetic makeup of a bull by examining his DNA sequence. So the bull’s DNA is extracted from his hair, tissue or semen. It then goes through a complex laboratory procedure to analyse the bull’s DNA makeup – called genotyping. He might be found to be carrying the genes  that influence ‘carcass weight’ or ‘daughter milk’ etc.

The results of this process are then used to make his initial ‘Parent Average’ index more  accurate. This can be seen by the ‘reliability %’ figures increasing. What this is saying is that we are now more confident about knowing what the bull’s genetic merit is, than we were when we just had his parents figures to go on. Genotyping can also confirm the parentage of a bull.


The French Blonde d’Aquitaine AI Sire ‘Hashtag’ (BA4550) is a good example of a ‘before and after’ case for genotyping.

‘Hashtag’ in his French AI catalogue page.

Before Genotyping

His backpedigree was entered onto the ICBF database and he got his initial ‘Parent Average’ stars. These are an average of the star ratings that his sire and dam had.

  • He was only 2 stars for the ‘Replacement’ and ‘Terminal’ indexes.
  • He was nearly 4% for calving difficulty and had no docility rating.
  • He had low star ratings for the carcass traits.
  • His ‘reliability %’ figures are very low.

You would be very disappointed and annoyed with these index figures given that he has already sired nearly 500 calves in France and following is their summary of what they found out about his stock:

  • Easy Calving plus muscle
  • Genetics combining beef – calving ease-maternal qualities.
  • The best blond bull on calving ease.
  • Clear cut muscular potential

So given what his already known about his progeny in France, one would expect that when he is genotyped that the traits that his progeny have been found strong for in France should also be identified in his DNA through genotyping.

After Genotyping

By putting ‘BA4550’ into the ICBF ‘Animal Search’ and then clicking on the ‘Index Comparison’ tab the table below appears. A green circle indicates an increase in a figure and an orange circle indicates a decrease. As expected, his genotype data now pulled his figures way more in line with what had been found out about him in France, compared to what his ‘Parent Average’ figures were suggesting.

  • His calving ease decreased from 3.9% to 2.6%
  • His maternal traits improved: Milk, Calving Interval, Age 1st Calving & Survival
  • His ‘muscle’ traits improved: Carcass Weight & Carcass Conformation
  • His reliability % figures all increased from the mid-teens to the mid 30’s.
  • His ‘Maternal Calving’ got worse but this is not unexpected as he is only rated ‘95’ in France for this which is below average.

Find out more about the effect a bull’s Genotype has on his Index by clicking on the ‘Index Comparison’ tab in the ICBF ‘Animal Search’

All of the data used in this article is freely available on the ICBF website. Enter an animal’s tag number into the ‘Animal Search’ and then click on the tabs to find out more about how an animal’s index is calculated.

This article has been prepared by ICBF in good faith on the basis of information provided to it. No representation or warranty expressed or implied is made or given by ICBF as to the accuracy, reliability, completeness of this article. ICBF shall not be liable for any losses (whether direct or indirect), damages, costs or expenses whatsoever, incurred or arising from any use of or reliance on this article or the information contained in it by any person.