FAQ: How is a bull’s ‘Milk’ figure calculated?

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

  1. Backpedigree

The first ‘Milk’ 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 ‘Milk’ from the calf’s very first evaluation compared to the one after the genotype has been included.

3. Foreign Data

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

4. Irish Data

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

 Reliability %

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

Bull examples:

‘Bavardage’ is a Limousin AI Sire. In terms of steps 1-3 above: His back pedigree is in the ICBF database, as is his genotype. He is by ’On-Dit’ out of a ‘Dauphin’ cow which is a very strong maternal back pedigree. ‘Milk’ is evaluated in his country of origin which is France and has been included in his evaluation here. He is rated at 118 in France at 98% reliable which is an excellent index for Milk

In terms of his ‘Irish Data, the ‘milk’ data of his daughters 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 ‘Bavardage’ (or his AI Code ‘AGB’).
  3. Click on ‘Daughter milk (kg)’ which is shaded in blue.
  4. Scroll down to the 2 tables that say, ‘Maternal Weaning Weight’ and ‘Cow Milk scores’.

Maternal Weaning Weight

This is weight data that has been recorded on progeny of daughters of ‘Bavardage’. This data would have been recorded on farm by farmers who weight record as well as those taking part in the WHPR and BEEP schemes. His Daughters progeny grew faster than their herdmates as they had daily gains of 1.16 while their herdmates grew at 1.12kg/day.

Cow Milk scores

This is a rating that farmers give their cows as part of the BDGP scheme as regards how milky they think their own cows are. So Irish farmers gave his daughters and average ‘milk’ rating of 4.2 while their herdmates were scored lower. So basically, Irish farmers have found his daughters to have more milk than their herdmates and have recorded this through the BDGP scheme.

Putting all these pieces of information together results in ‘Bavardage’ being rated as a 5-star bull for ’milk’ in Ireland with a 93% reliability rating.

BDGP & BEEP

The BDGP and BEEP schemes have been crucial in terms of generating the genomic and ‘farmer recorded’ data. As can be seen above, both sources of data have made the difference between this bull receiving a proof based on back pedigree and foreign data compared to one with so much Irish farmer recorded data included as well as the bull’s genotype and the genotypes of his daughters.

Bavardage daughter in France