Learn about Milk EBVs in
Angus GROUP BREEDPLAN

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Milk EBVs
48 - How does Breedplan estimate milk EBVs
49 – How is the Milk EBV estimated
50 – What is the difference between the Milk EBV and the Maternal Value EBV
51 – What does the Milk EBV mean in terms of calf weight
52 - Young bulls have low accuracy Milk EBVs - are the likely to change
53 – How is the Milk EBV estimated for imported sires/dams

48 : How does Breedplan estimate milk EBVs. . . . . . . . . . . . . . . Go to Top

Breedplan does not estimate how much milk a cow gives, rather it estimates how much of her calf's weaning weight can be attributed to the difference between her inherited milk potential and the breed or herd benchmark. The EBV is reported in kilograms, above (+) or below (-) the benchmark of zero .

It does not reflect the amount of her total milk production which, in addition to genetic factors is influenced by non genetic factors such as nutrition, age and management.

In the case of a sire, Breedplan estimates how much of the 200 day weight of his daughters calves result from the genetic component of her milking ability that she inherited from the sire.

49 : How is the Milk EBV estimated . . . . . . . . . . . . . . Go to Top

Because we don’t milk beef cows we can't get a direct measure of milk production, instead we use an indirect measurement such as weaning weight as an indicator trait.

This is not really an accurate measure of a dam’s milk production as the calf’s weight at weaning is a combination of the effects of the calf’s growth genes inherited from both sire and dam, and both the genetic and environmental (paddock and seasonal conditions) effects on the dam’s milk production.

Breedplan only estimates the genetic component (breeding value) of the cows milk production .

To do so, Breedplan applies a number of adjustment factors to the calf’s 200 day weight to estimate how much of the adjusted 200 day weight is due to the genetic milk component. These calculations and adjustments are based on well proven research and whilst mathematically complex, field experience strongly validates the accuracy of the Milk EBV.

Where a sire does not have daughters in production, for example a yearling bull, the milk EBV is estimated from his parents and close relatives. This is known as a non-parent EBV and has low accuracy. Once his daughters have calves, their 200 day Wt. progeny records are used to update his milk EBV, increasing accuracy considerably.

Note : Much of a cow's actual milk production is the result of feeding, not genetics - if in doubt just look at the differences in weaning weight and condition of calves from the same cow in a drought year compared to a good season.

50 : What is the difference between the Milk EBV and the Maternal Value EBV . . . . . . . . . . . . . . Go to Top

Angus does not publish the Maternal Value EBVs for any animals.

51 : What does the Milk EBV mean in terms of calf weight at 200 days.

Research has demonstrated that a 1 kg increase in Milk EBV equates to a 0.1 kg increase in daily milk production. This means an extra 20 kg of milk over 200 days of lactation.

Given that a calf converts milk to body weight at around 10% efficiency, this 20 kg extra milk equates to an extra 2 kg calf weight at 200 days of age. Sounds trifling at that level perhaps but take a =10 kg cow and we are looking at an extra 20 kg of weaning weight that results from Mum’s extra milk, compared to the breed base.

52 : Most young bulls have low accuracy for Milk EBVs - are these EBVs likely to change . . . . . . . . . . . . . . Go to Top

As most sale bulls do not yet have daughters in production, their milk EBV can only be estimated from their parents EBVs. These preliminary EBVs are referred to as “mid parent EBVs”

Because of this, and the fact that milk is a lowly heritable trait, the accuracy of the EBVs for young bulls will usually be between 30 and 50%. As such they will be subject to fluctuation, either up or down, as half-sib and daughters progeny information becomes available.

Even with low accuracy ratings, EBVs are still the best estimate with which to compare young bulls to the breed base for milk, and will be more accurate than visual selection. See AppendixA

53 : How are Milk EBVs of imported (introduced) sires estimated. . . . . . . . . . . . . . . . . Go to Top

As there will be no maternal records within the breed database for that sire, milk EBVs cannot be estimated until he has daughters have weaned their first calf unless the imported sire has performance records in its country of origin. If so, these records are “imported” and used to establish the starting EBV in Australia.