The Heavy Grain Index estimates the genetic differences between animals in net profitability per cow joined in a commercial self replacing herd targeting pasture grown steers with a 200 day feedlot finishing period for the grain fed high quality, highly marbled markets.
Steers are assumed to be slaughtered at 760 kg live weight (420 kg carcase weight with 30 mm P8 fat depth) at 24 months of age.
Daughters are retained for breeding and therefore maternal traits are of importance. There is a significant premium for steers that exhibit superior marbling.
The graph below shows the emphasis that has been placed on each trait group in the Heavy Grain Index.
The following table shows the indicative change in traits after one generation if producers select animals using the Heavy Grain Index.
The indicative response reflects the change if the Angus Published Sires (at the November 2014 Angus GROUP TACE analysis) were ranked on this selection index and the Top 10% selected for use within a breeding program. The response will differ if a different group of animals was available for selection and/or a different selection intensity was applied.