Index Comparison within the Multi-Breed by Kari White

One of the many benefits of the American Gelbvieh Association (AGA) participating in the International Genetic Solutions (IGS) multi-breed analysis is the fact that it makes our EPDs comparable with other breeds such as Simmental, Red Angus, and Limousin. This commitment to conformity makes it easier for bull buyers to compare genetic merit of animals from different breeds.

For many years now, the AGA has been encouraging the use of indexes to make more continuous genetic improvement in the directions of terminal value, maternal genetics, and feed efficiency. As a reminder, the AGA offers three indexes:

$Cow: Represents the genetic value in dollars of profit of an animal when retained as a replacement female relative to other animals in the herd. A higher number represents more profitable genetics for maternal productivity. $Cow will serve producers in selecting bulls that will sire daughters with stayability and reproductive efficiency as well as other traits that lead to profitability in a production system, such as milk, calving ease, moderate mature weight and the ability of calves to gain. A female’s genetics also influence the performance of her calves in the feedlot and at slaughter, so traits such as feed efficiency and carcass value are also included in $Cow.

When to use: Use $Cow when females will be retained for replacements and cull heifers and steers are slaughtered.

Efficiency profit index (EPI): An economic selection index developed to aid producers in selecting for more feed efficient cattle that still have acceptable amounts of gain. The EPI provides slight negative pressure on intake, while keeping gain at a constant value. Calving ease and growth to weaning are also included since they are economically relevant traits a terminal sire will influence in production. By selecting on this index, producers will be able to find those animals that gain the same amount as their contemporaries while eating less.

When to use: Use EPI to improve efficiency in your herd.

FPI: An economic selection index designed to aid producers in selecting sires whose progeny will perform in the feedlot and are sold on a grade and yield standpoint. Well ranking sires for FPI have higher marbling and carcass weight than their contemporaries.

When to use: Use FPI when all offspring out of a sire will be slaughtered.

Many AGA producers are now using several different breeds as part of a crossbreeding program to produce hybrid animals for their buyers. These breeders might ask: How does the AGA indexes stack up against indexes in other breeds? Are they comparable? While not identical, two of the AGA indexes are closely related to two indexes used by the American Simmental Association (ASA). The AGA FPI is closely related to the ASA Terminal Index (TI). The AGA $Cow index is closely related to the ASA’s All Purpose Index (API). So what does this mean for breeders? It means that when assessing animals, the indexes are closely enough related to get a rough idea of how the animals compare.

Remember, indexes are tools that allow producers to select for several EPDs at once, making selections more efficient than selecting on one trait at a time. Indexes weigh traits based on their importance to a producer’s bottom line by using a trait’s economic and genetic value. Indexes are a good way to put selection emphasis on traits that are economically relevant. Indexes are simple to use because a greater number is always more favorable, meaning a greater amount of profit for an animal’s progeny compared to its contemporaries.