BREEDPLAN analyses cattle in contemporary groups to take out the influence of as many of the non-genetic effects as possible (eg. feeding, years, seasons). The underlying principle is that only animals that have had an equal opportunity to perform are directly compared together within each contemporary group.

If the contemporary groups are not correctly formed, the EBVs calculated will be less accurate and possibly misleading. Most of the problems that breeders encounter in “believing” their BREEDPLAN EBVs can be traced back to incorrect contemporary grouping – either calves being fragmented into isolated groups of only one or two animals (and thereby virtually eliminating those calves from any comparison with their peers) or by not differentiating between calves that have had different levels of management or feeding.

Importantly, the breeder has a major influence on deciding which animals will be directly compared within each contemporary group. This influence is through both their on farm management and the submission of management group information to BREEDPLAN. In this manner, it is vital that breeders understand the factors that influence the formation of contemporary groups to ensure they maximise the effectiveness of their BREEDPLAN recording.

BREEDPLAN automatically creates the contemporary groups of animals for comparison based on criteria similar to that outlined below. The exact criteria used will differ depending on the trait being analysed.

1. Herd
   • Only calves bred and weighed in the same herd will be directly compared in the same contemporary group.
   • This herd definition can be extended to include “associated herds” which have calves bred and managed as part of a larger herd. The most common example is where members of a family (eg. children) have a small number of animals registered in their own name that run as part of the main herd on the property.
2. Calving Year
   • Only animals born in the same “calving year” will be compared together in the same contemporary group.
   • Usually the calving year is the same as the year of birth of the calf. However, for herds whose calving period runs into the next calendar year (eg. from November through to March), "calving year" can be specified to span the period running across two different calendar years. This may be applicable to herds in northern Australia that calve over the summer months. In these cases, a financial year is more appropriately used as the “calving year”.
3. Sex of Calf
   • Only calves of the same sex at measurement will be directly compared in the same contemporary group (ie. bulls with bulls, heifers with heifers, steers with steers). Note that males that are weighed initially as bulls and then castrated will have their first weight compared with all the other males and their second weight only with the steers.
4. Number in Birth (Singles/Twins)
   • Only calves of the same birth number will be compared together in the same contemporary group. In other words, single calves will not be compared with twins.
   • While twins can potentially be compared with other twins, the low occurrence of twin births generally means that very little performance information from twins is used in the BREEDPLAN analysis.
5. Birth Status (ET/Natural)
   • Calves conceived naturally or by AI will be directly compared together in the same contemporary group but they will not be compared with embryo transfer (ET) calves. In other words, ET calves will be analysed in a separate contemporary group. Furthermore, the amount of information available on the recipient dam will then determine the formation of the contemporary group for ET calves. More specifically, in most BREEDPLAN analyses, ET calves will only be directly compared with other ET calves that have been reared by recipient dams of the same breed (and the recipient dam information has been recorded with the breed society).
6. Dam Age (Parity)
   
   • The birth performance records for calves out of first calf heifers (up to 3.5 years of age) are not compared with birth performance records for calves out of other cows. NOTE - This heifer/cow distinction is only used for performance traits that are measured up to and including birth (i.e. birth weight, gestation length, days to calving).
7. Breed
   • In some BREEDPLAN analyses, only the performance records for calves of the same breed will be compared together in the same contemporary group. NOTE - The breed of an animal is only used in the formation of contemporary groups in some BREEDPLAN analyses. In other BREEDPLAN analyses, either a) only the performance for pure bred animals is included or b) the performance from cross bred animals is included in the same contemporary group and adjustments for heterosis are made.
8. Measurement Date
   
   • Only animals measured on the same date will be compared together in the same contemporary group. In addition, only animals with the same measurement history will be directly compared.
   • For example, the 400 day weight performance for two animals will only potentially be directly compared if:
     • both the 400 day weights were recorded on the same day
     • any weights previously submitted to BREEDPLAN for these animals (eg.200 day weights) had also been recorded on the same day.
9. Calf Age
   
   • Only animals of similar age will be directly compared in the same contemporary group. When all the other criteria have been used to place animals into a contemporary group, the group is divided (sliced) into animals of similar ages. “Slicing” is done to ensure that the calves being compared have been run under comparable seasonal conditions. For example, if the age slicing for 200 day weight is 45 days. The first calf born in the group is the start and the contemporary group will include all animals born in the next 45 days. After this the next calf is found and this becomes the start of the next contemporary group.
   • NOTE – This age slicing varies depending on the trait being analysed. In addition, the age slices used may vary from breed to breed. The following table provides an indication of the standard age slices used by BREEDPLAN.
10. Breeder Defined Management Group
    
    • Only animals in the same breeder defined “management group” will be directly compared in the same contemporary group.
    • There are two different forms of breeder defined management group.
      1. the “Birth Management Group” allows breeders to describe different treatments of the cows prior to the birth of the calf. For example, where one group of cows have had different feed availability that may affect the birth weight and/or calving ease and/or gestation length when the calf is born.
      2. the “Post Birth Management Group” allows breeders to identify animals that have received different treatment or management following birth that has influenced their performance. This treatment may be deliberate (eg when some of your young bulls receive supplementary feeding and others do not) or accidental (eg if a calf is sick).

Providing BREEDPLAN with management group information is the responsibility of the breeder. By assigning animals into management groups, breeders are acting as “eyes” for the BREEDPLAN evaluation.