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Understanding the (API) “All Purpose Index”
and (TI) “Terminal Index”
As seed stock producers we want to give you all the information we can about the genetic potential of
our bulls.
With adjusted weights, ultrasound readings and EPD’s, this amount of data is sometimes
overwhelming and may be confusing.
What ranchers really want to know is which bull will make them
the most money when all factors are considered.
The American Simmental Association offers an
All
Purpose Index
(API) and a
Terminal Index
(TI). These
indexes can simplify your bull comparisons by
combining all EPDs into just one number.
In developing these index formulas, the input price and cost averaged over the last 5 years as reported by
Cattle Fax was used. Everything, from the cost of hay, corn and price grids on quality grade, yield grade
and carcass weight were taken into consideration in the API and TI indexes.
The API evaluates sires being used on the entire cowherd (bred to both Angus first-calf heifers and
mature cows), with a portion of their daughters being retained for breeding and the remaining heifers
plus all steers put on feed and sold grade and yield. All the EPDs, with the exception of tenderness, are
taken into consideration in this index.
The TI is designed for evaluating a sire’s economic merit in situations where they are bred to mature
Angus cows and all offspring are placed in the feedlot and sold grade and yield. Consequently, maternal
traits such as milk, stayability and maternal calving ease are not considered in the TI index.
The difference between the API and TI points out the importance of buyers determining how they use
their bulls. If they retain replacements then the API may be the most important number in the bull sale
catalog. If they sell all calves, retain ownership and sell on the grid, then TI is what they should consider.
Using the Indexes to Determine Value Difference Between Two Bulls
Both the API and TI are designed to make comparisons between bulls when all economically important
traits are considered from birth to harvest. The index units are in dollars per cow exposed. The
difference can be used to determine how much you can pay for one bull compared to another. For
example, when buying an API, all-purpose-type sire, you can quickly figure a bull scoring +100 for API is
worth an extra $6,000 over a +50 bull if both sire 30 calves/year over 4 years ($50 difference x 30 hd. x 4
yr. = $6,000).
DVAuction
Broadcasting Real-Time Auctions
Bid on our bulls and watch
the sale on DV Auction.
Go to
Be sure to register before the sale.
