International Genetic Solutions
WHAT IS IGS?
IGS (International Genetic Solutions) is the world’s largest beef genetic evaluation system. A collaboration of progressive cattle breed associations, with nearly 18,000,000 total animals and more than 340,000 annual registrations, IGS provides beef producers with some of the most powerful and user friendly selection tools available, including a full suite of EPD’s.
BOLT EPD accuracies have experienced the most change, usually lowering numerically and especially for non-parent animals, however the reported accuracy will be more accurate.
Accuracy refers to the amount a reported EPD can possibly change as more data is added. EPD values with higher accuracy result in less possible change for the value over time. More accurate accuracies better represent the amount of possible change for each EPD.
WHAT IS THE DIFFERENCE BETWEEN AN EPD AND AN EBV?
An EBV (Estimated Breeding Value) is defined as an estimate of the animals own genetic value for a particular trait.
An EPD (Expected Progeny Differences) is defined as the genetic merit of an animals progeny.
As the parent contributes on average 50% of its genes to its progeny, an EPD is theoretically half an EBV (ie; 0.5 * EBV=EPD). However, whilst this is theoretically true, a number of other factors means that this is not a great way to make comparisons between EPD’s and EBV’s.
Also, EPD’s have traditionally been analysed in a single trait evaluation model, whilst EBV’s have been calculated in a multi-trait evaluation model. Now, with the application of the BOLT software, IGS has moved to a multi-trait evaluation model for carcass traits.
WHAT EPD’S WILL BE REPORTED?
- CED (Calving Ease Direct) – % of unassisted births in heifers.
- CEM (Calving Ease Maternal) – % of unassisted births in first calving daughters.
- BW (BirthWeight) – Pounds of Birthweight.
- WW (Weaning Weight) – Pounds of weaning weight adjusted to 205 Days of age.
- YW (Yearling Weight) – Pounds of weight adjusted to 365 Days of age.
- Milk – Pounds of weaning weight due to Milk.
- MWW – (Maternal Weaning Weight) Pounds of weaning weight due to milk and growth.
- ST (Stayability) – % of daughters remaining in the herd at 6 years of age.
- DOC (Docility) – % of progeny receiving a Docility score of 1 (ideal).
- YG (Yield Grade) – USDA Yield Grade Score.
- CWT (Carcass Weight) – Pounds of Carcass Weight.
- REA (Rib Eye Area) – Ribeye in square Inches.
- MB (Marbling) – Marbling score.
- FT (Back Fat) – Rib Fat in Inches.
WHY IS STAYABILITY IMPORTANT?
Stayability is a prediction of whether a cow will stay in production until she is six years old. It is a trait that includes fertility but also several reasons for culling, such as hoof and leg soundness, and udder quality.
Longevity is an important trait for cow calf producers in Australia. The ability to ensure that replacment females have the best opportunity to be productive in your herd at 6 years of age ensures that each female has the ability to return on the investment producers make from carrying her into production.
Stayability is a measure of reproductive longevity and benefits herd productivity in two ways; through decreased need for replacements and higher average weaning weights due to a larger proportion of mature cows in the herd.
WHY ARE EPD’S REPORTED IN IMPERIAL MEASURES?
IGS uses the North American Imperial measures of pounds and inches. Whilst the Australian data will be easily converted by the software from the metric measures that breeders use, we need to continue to report the EPD’s in Imperial measures in order to maintain the comparison with USA and Canadian animals. The software will report the Rank % of each EPD which will assist with understanding what each value means.
WILL I NEED TO MEASURE PHENOTYPES IN IMPERIAL MEASURES?
No. Once you have submitted your metric phenotypes on your cattle, the software will convert them into imperial measurements before they are uploaded into the IGS database.
HOW DOES RANK % WORK?
The software will report the Rank% of each EPD for each animal. The Rank% is defined as the position of the EPD for each animal within the range of EPD’s for all animals in the breeds percentile band. As such, the Rank% is a more useful value than the EPD itself.
WILL ANIMALS CHANGE THEIR RANK% FROM EBV’S TO EPD’S?
Many animals Rank% will remain very similar to their current Rank% however, there will also be substantial movement up and down for some animals, which can be understandably disconcerting for breeders.
There are several reasons that contribute to this and include:
- EBV’S VS EPD’S : As discussed before, EBV’s predict the animals own genetic value for the trait, whilst EPD’s predict the genetic value for the animals progeny.
- MORE PHENOTYPES : IGS will use all phenotypes, not just those collected in Australia. As a result, some animals that have progeny in Australia as well as in USA and Canada will have all the International and Australian phenotypes included in the IGS calculation. This will also have some flow on effect on the progeny of these animals within Australia.
- GENOMIC INFORMATION : Genotypes are not currently used in calculating Shorthorn EBV’s, however they will have an effect in the calculation of IGS EPD’s.
- DIFFERENT TRAIT DEFINITIONS : There are subtle differences in how traits are defined, such as Yearling Weight. Yearling weight in EBV’s is adjusted to 400 days of age, whilst Yearling Weight in EPD’s is adjusted to 365 days of age. This is also true of Carcass traits where the current EBV’s are reported as estimated differences in a standard 300kg steer carcase while the IGS EPD’s are adjusted to the estimated differences in progeny at 475 days of age.
- DIFFERENT BASE GROUPS : In genetic evaluation terms, the base group of animals (defined by a range of birth years) is set to have the same EBV/EPD average from one run to the next. All animals are compared through genetic linkage to the base group for their own EBV’s/EPD’s. The base group used in one system is not the same as the base group used in another system.
WHY HAVE ACCURACIES CHANGED?
More accurate accuracies. BOLT EPD accuracies will see the most change, usually lowering numerically, especially in non-parent animals, however the reported accuracy will be more accurate. With BOLT EPD’s, accuracy can be more directly solved (without using assumptions), which results in a more reliable accuracy, although that accuracy will often be numerically lower. However, the newly reported accuracies with BOLT should better represent the possible changes for the EPDs.