Interbull production and type (MACE) proofs became official in February 2001, replacing the outdated conversion formulae method.
What Does MACE mean?
Multiple-Trait Across Country Evaluations
The February 2001 genetic evaluations represented a major step forward in the international comparison of bulls for Type Traits. The MACE procedure, which is already in use in most other countries will be utilised to combine both foreign and domestic information. This will mean that all bulls are directly comparable for all type proofs on a UK basis.
Globalisation of Dairy Cattle Breeding has provided farmers in the UK with genetic material from all around the world. In response to these developments, there has been an increase in the demand for information regarding the performance of both animals and the genetics from the exporting countries. Considerable effort has been made to develop a system, which provides a multiple-trait across country evaluation, which allows for ranking of all bulls on a countries own base. MACE is particularly useful because bull evaluations are allowed to rank differently in each country. The conversion formulae, which have been used previously, assume that all bulls rank the same in all countries.
The MACE procedure utilises relationships among all bulls. For example a half or full brother in one country will contribute information to his brothers' proof in other countries. For bulls that have no UK daughters, the MACE system will combine the UK pedigree index together with the foreign bull's proof, which is an improvement over the current method used of direct conversion. Simultaneous analysis of information from multiple countries is therefore possible and not just for two, which was a limitation with conversions.
Summary of why the changes have been made
- Conversion formulae are based on a highly selected group. Interbull uses information on male relatives allowing unselected sires to contribute.
- Conversion formulae are based on relatively small numbers of bulls. Biased proofs can have large impacts. I/B uses younger sires. E.g. 1st-crop ¾ sibs in both countries. Excludes older sires that may not be relevant in current population. TCS systems may have been modified.
- MACE allows simultaneous analysis of information, which overcomes the problems experienced in converting dual sampled sires.
- In MACE, relationships between animals are correctly accounted for.
- Interbull produce a Foot & Leg composite based on the foreign country Foot & Leg composite – this appears to offer a massive improvement over the current Foot & Leg composite used for foreign sires.
- The Industry agreed MACE linears are more accurate than converted linears.
The four composites and TM will be produced as follows:
These traits are not scored universally so Interbull do not produce composites for these traits, thus: They must be calculated from MACE linears. This is the same procedure as is currently used to produce composites from converted proofs.
Foot & Leg Composite
The Foot & Leg score produced by Interbull will be used. Adopting this composite enables a new method of TM prediction. N.B. Italy does not have a F&L composite, so it must be predicted from Foot Angle and Rear Leg Side.
This composite will be calculated from the MACE linears. Mammary composite is a subjective trait, composed differently in each country. By calculating the composite from the MACE linears it allows the traits that are included in the composite to be determined by us, not each individual country.
Type Merit will be calculated by weighting the four composites. WHY? TM produced by Interbull from country of origin TM – highly subjective, and there are large differences between countries. Both of the Foot & Leg linears describe shape not functionality so both are poorly correlated with Foot & Leg composite and Type Merit. Any Type Merit prediction made directly from linears would have a low F&L component. It will be easy to control Type Merit if the weights on the composites are altered.
The weights used to determine TM from four composites are the same as the weights used to determine final score from the four composites for females, these are:
20% Body Conformation
20% Dairy Character
20% Legs and Feet
These weightings are applied before the composites are scaled.
Which proof to publish (type only)
Bulls who were solely or part tested abroad and actual UK proof rel < 80% – use MACE proof.
All bulls with actual UK proof rel >=80% use actual UK proof.
Bulls who only have daughters in UK (I.e. UK progeny tested sires) - use actual UK proof
An 80% reliability is equivalent to about 45 effective daughters.
The 80% reliability threshhold was chosen because:
If the sire may have information in the UK that wouldn’t be contributing to Interbull proof until proof Rel >85% at least. Effectively this information would not be used anywhere.
If level is higher, it may delay any UK information being seen by one or more proof runs.
Summary of Publishing Rules:
Publish actual UK proofs for bulls with daughters only in UK or where UK proof reliability > =80%
MACE F&L composite
Body / Dairy composite calculated from MACE linears
Mammary composite calculated from MACE linears.
TM calculated by weighting four composites.