An indicator trait is one that adds accuracy to the prediction of an economically relevant trait (ERT) due to its genetic relationship with the ERT. For a trait to be categorized as an indicator, there is no explicit economic benefit for changing its phenotypic value other than through its correlation to an ERT. A classic example of an indicator would be birth weight. Changes in birth weight can be used as an indicator of growth rate and incidence of calving difficulty. However, if the traits growth rate and calving difficulty are already considered in a producer's selection program, there is no inherent economic value for changing birth weight. Designation as an indicator trait does not mean the trait is inherently invaluable. Indicator traits are often times included in a multiple-trait genetic evaluation of an ERT to add accuracy to the prediction of the EPD for the ERT.
The distinction between ERT and indicator traits in a breeding program is important. Selection on ERT, as opposed to their indicators, is a key to improving profitability. By identifying those attributes that are considered economically relevant, selection focus can be narrowed, resulting in more rapid genetic improvement and improved profitability. Ultimately, no breed association produces EPD for every ERT. Realizing this limitation, it is recommended to (in the following order):
- Identify the ERT for your individual marketing system and make selection decisions using EPD for those ERT (when available).
- Select using EPD for the indicator trait when EPD for the ERT is NOT available.
- If EPD for either the ERT or indicator is NOT available, select on phenotype or ratios for the ERT.
- Select on phenotype or ratios of the indicator trait.
A more thorough discussion of the relationship between ERT and indicator traits can be found as a portion of the Sire Selection Manual published by the National Beef Cattle Evaluation Consortium.
- Golden, B.L., D.J. Garrick, S. Newman, and R.M. Enns. 2000. Economically Relevant Traits: A framework for the next generation of EPDs. Proceedings of the 32nd Research Symposium and Annual Meeting of the Beef Improvement Federation. Pp. 2-13.