Collecting data for Angus BREEDPLAN requires accuracy and commitment to the recording of performance information. The performance record is king, however is not the only valuable piece of information required for EBVs to be calculated. This is because in order to take out non-genetic effects, BREEDPLAN needs to understand where animals have and haven’t had equal opportunity to perform.
Pedigree information in the early days enabled breeders to predict, to a certain degree, the type of offspring a bull or cow might produce. This concept of using pedigree information to predict potential offspring is still used today, with one fundamental difference: data. The amount of objective data and information which now feeds in to what we know about an animal is huge and this is why breeding values are so valuable to a breeding program, but also why accuracy of pedigree is still crucial.
Breeding values draw in information from the performance recording on an animal, the performance recording done on relatives of the animal (pedigree) and from genomic information, which links performance recording to genes rather than animals. If this information is incorrectly allocated then the breeding values would link the wrong information to an animal and calculate an incorrect estimated breeding value (EBV).
Accurate recording of the date the performance record was taken can be very significant in the development of EBVs, due to a number of traits being significantly affected by the exact age of the animal (e.g. 200 day, 400 day, Scrotal size). The same is true for birth date as the date of the performance record was taken refers back to this date.
Calves are typically born over a given calving period (e.g. 6 weeks) and this can mean calves within the same herd can be as much as 42 days older then others. The result of this is that older calves have had more days of performance than their herd mates, which may lead to misleading information if not understood in the context of the situation.
For example, if you have two calves and when weighed for 200 day weight on day 150, calf 1 weighs 150 kg and calf 2 weighs 138kg, you could incorrectly assume calf 1 has the better growth rate. If they were the same age this would be correct, however if as the example below shows calf 2 is 30 days younger than calf 1, then in fact, if you compare the two animals for their weight at 150 days of age, we see that calf 2 is 15kg heavier then calf 1 was at that age. So calf 2 has the better growth rate but the performance record alone would not enable us to determine this.
The ability to understand the context of the data is critical for accurate EBVs to be developed and this is also why management groups play a critical role in the calculation of EBVs.
Recording the management group information is one of the most important aspects of collecting performance information for Angus BREEDPLAN.
Management groups or contemporary groups separate the information for an animal based on any situation where their performance has been affected by different non-genetic influences to other animals. In practical terms, animals that have been run in the same management group and have had equal opportunity to perform should be grouped together.
Some examples of where animals should be recorded in separate management groups are:
It is important to note that the smaller the management group the greater the reduction in the ability of the analysis to identify differences and draw relationships between animals for the development of EBVs.
EBVs enable us to assess the genetic merit of an animal and remove the influence of non-genetic effects (e.g. management, nutrition, feed, year, season, injury, health status) from our selection decisions. EBVs do this by examining the performance of an animal relative to the performance of other animals in the management group and then compares this performance to how the genes of the animal have performed in other herds or management groups.