Bull Selection with Indexes

Spring is quickly approaching and that means warmer weather, green grass, and your mailbox full of bull sale catalogs.  If you are like me, you are receiving a cattle sale catalog about every day wanting you to come and select your next great herd bull.  How do you make that selection?

Those catalogs are filled with loads of information: pedigrees, individual performance and carcass data, growth EPDs, maternal EPDs, carcass EPDs, DNA data, indexes and probably a few pictures. There is information overload.  Isn’t more information to make selection easier?  How do we use all of this data? 

One of the challenges with all of the information and wide variety of EPDs is balancing the different traits.  Do you select the bull with a higher yearling weight and average carcass traits or do your select the bull with higher carcass traits and average growth rate?  The standard extension answer is “that depends”.  Which one is going to be more profitable for your operation? That is tough to determine with only EPDs as they do not account for cost and profitability.

Fortunately, many of the breed associations are developing “selection indexes”.  A selection index is defined as a combination and weighting of multiple traits and their relative economic impact into one value that can be used to rank animals.  Indexes are generally expressed as dollars per head and are used to compare sires in dollar or profit differences for progeny in a production scenario.  Majority of the breed associations compute a maternal (all purpose) or a terminal (feedlot) index.

Maternal indexes are focused for cow-calf producers and the assumption that replacement females will be retained.  They incorporate economically relevant traits for maternal, preweaning performance and reproduction.  Terminal indexes are designed to select for a combination of feedlot performance and carcass merit.  They are useful in comparing the profitability of progeny post weaning.

The key to success in selecting sires based on the appropriate index is to use the market endpoint that aligns with your operation.  For instance, using a terminal index for selecting a sire for producing replacement females is discouraged, as terminal indexes place zero economic weight on maternal traits.

All of the breed associations publish a wide variety of indexes.  Each one is developed for a defined situation or objective.  In order to determine which index works best for your operation, understand what economically relevant traits are included in the calculation and select the index(es) that most closely fit your operation.  For information on a specific index, refer to the respective breed association.

Selection index provide a natural connection between the net merit of an animal’s genotype and its relationship with profit.  Indexes are useful tools to help simplify your bull selection and help wade through all of the information overload that could accompany bull sale catalogs.

Source: David Hoffman, MU Extension Livestock Specialist