Breeding Week 2024: Understanding the maintenance sub-index
The maintenance sub-index of the EBI represents 8% of the total euro value of the EBI, but what does the maintenance figure actually represent and what should it mean to you?
In this article, Teagasc Dairy Specialist, Stuart Childs talks us through what the sub-index means and how it can be used to influence mature cow weight at farm level.
The maintenance value in the EBI report gives an indication of the expected cost of growing a replacement and maintaining her as a cow in a dairy herd based on her genetic make-up. So in essence, it gives an indication of the cost of keeping a cow, without her producing any output i.e. what does it cost for her to stand up and lie down and walk about. The value that you see on the EBI report is representative of a mature cow which is a third calver in mid lactation (June/July).
A €0 value for maintenance indicates a cow that will be 641kg and as you move up from this or down from this the expected live weight of the cows will change.
Table 1. Maintenance Index value (€) and the associated projected live weight (kg)
| Maintenance Index (€) | Projected liveweight (kg) |
|---|---|
| -10 | 691 |
| -5 | 666 |
| 0 | 641 |
| 5 | 616 |
| 10 | 591 |
| 13 (National Average) | 576 |
| 15 | 566 |
| 20 | 541 |
| 25 | 516 |
| 30 | 491 |
Ever €5 change in maintenance results in a change in the live weight of the cow by 25kg and depending on the direction of movement the cows will be either getting heavier or lighter.
Positive € values for maintenance are good as they indicate lower live weight animals and lower live weight animals have lower feed requirement as they do not need to consume as much to maintain themselves. This means that they have extra energy available to partition towards milk solids production, which means for similar intakes lower live weight cows can produce more milk solids than higher live weight cows.
Accordingly, negative € values are less desirable as they deliver an increase in the live weight of the cow and an associated increase in dry matter requirement to simply maintain themselves, resulting in less energy available to apportion to the production of milk solids.
Currently, the national average maintenance value is €13 which is equivalent to a mature cow live weight of 576kg.
Ultimately, it is a farmers own decision to decide the size of the cow that they like and want on their own farms, but it is important that in making that decision that farmers are aware that choosing low or negative maintenance bulls will increase the live weight of their cows in the future and that these cows will require more feed to simply maintain themselves. Choosing positive and higher € value maintenance cows is a decision to breed a more efficient and ultimately profitable animal for the future.
In the below video, Stuart provides an overview of the maintenance sub-index in the EBI:
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