FAQ – How is a bulls Carcass Weight Index calculated?

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There are 4 factors that will both contribute to what ‘Carcass’ index figure your bull starts out with and also how it changes over time.1.Backpedigree, 2.Genotype, 3. Foreign Data, 4.Irish Data

1.Backpedigree

The first ‘Carcass’ index that a bull will receive is called a ‘Parent Average’ index. As the name suggests it is an average figure that is calculated from the index figures that his sire & dam have at the time of his birth. If the index figure of a close relative of the bull moves up or down significantly then this will also affect the index figure of the bull himself.

  1. Genotype

When a sample of DNA (e.g. straw of semen) is sent off and the genotype comes back this will then alter the figure that the bull got in his first evaluation run which would have been through his ‘parent average’ as explained above. So there could be a difference in a bull’s ‘Carcass’ from his very first evaluation compared to the one after the genotype has been included.

  1. Foreign Data

If a bull already has an index for ‘Carcass’ in another country and this data is sent to ICBF then this will also have an impact on shaping his ‘Carcass’ index in Ireland. ICBF routinely gets files of such index values from countries such as the UK and France

  1. Irish Data

The bull’s progeny having their Carcass data recorded on them here will be the final piece of the jigsaw in terms of his ‘Carcass’ index.

Reliability %

The number of herds that his progeny have their ‘Carcass’ recorded in together with the number of herdmates that they were reared alongside will determine by how much this reliability figure increases.

Bull examples:

‘Carrickbrack96 Hutch’ is a Charolais AI Sire. In terms of steps 1-3 above: His backpedigree is in the ICBF database, as is his genotype. He is by ’Thrunton Bonjovi’ and out of a ‘Nelson’ dam. Both his sire and maternal grandsire are both 5 stars for ‘Carcass Weight’. So he has a very strong terminal backpedigree. He has also been genotyped and that is included in his €uro-Stars here. Being an Irish bred bull, used mostly here in Ireland, he doesn’t have any foreign data feeding into his €uro-Stars here.

In terms of his ‘Irish Data, the ‘Carcass’ data of his progeny can be seen in the ICBF ‘Animal Search’ facility:

  1. Go to icbf.com
  2. Go to the Animal Search facility down the right hand side of the website and enter in ‘Carrickbrack96 Hutch’ (or his AI Code ‘CKH’).
  3. Click on ‘Carcass Weight (kg)’ which is shaded in blue.
  4. Scroll down to the 2 tables that say ‘Maternal Weaning Weight’ and ‘Cow Carcass scores’.

Carcass Performance of Progeny

The table above show the performance averages for his progeny:

Average (days): This shows that his progeny were on average virtually the same age as their herdmates when they were finished. This is a positive as it shows that his progeny did not need to be held onto and fed for longer to finish them which would have incurred more cost.

Carcass Weight (kg): His progeny had an average carcass weight of 394kgs versus their herdmates at 369kgs.

Conformation: On average his progeny had better conformation grades (U-) compared to their herdmates (R+)

Fat (1-5 scale): His progeny matched their herdmates for fat score.

Putting all of these pieces of information together results in ‘Carrickbrack96 Hutch’ being rated as a 5 star bull for ’Carcass’ in Ireland, across breed, with a 99% reliability rating.