Genetic selection now with X'Aim

New features have been added to X'Aim to provide genetic selection tools. These include:

• the ability to import genetic selection Indexes for animals
• view Indexes on the list of animals and in animal details
  
• 3 new mating strategies to balance genetic gain on Index, inbreeding and coancestry
• mating lists with predicted Index for the progeny of each mating (as well as inbreeding)
• export Index and comments as well as all other data

A quick genetics primer

Genetic improvement is the result of selecting superior animals to replace inferior animals through the use of breeding. The determination of what is "better" or "best" depends upon many things such as:

• what traits, or combination of traits, is more profitable?
• what traits or characteristics make animals healthier?
• what traits or characteristics are more appealing?
• what kind of animal does the environment support?
• what kinds of animal products does the market demand?

This determination is usually made by livestock or animal owners and breeders, and sometimes by a national or cooperative body representing the industry. The more formal terminology is "setting the breeding objective" and entire books are written on the subject.

What is important here is that the breeding objective, once formulated and applied, is represented by a single figure called an Index. This number can be used to rank animals, with better animals having higher numbers, and poorer animals having lower numbers.

Often the Index is in $ terms, and can be interpreted as such. For example, if there are two animals, one with an index of 100 and another with an index of 110, then the second animal is 10 index points better than the first. If this is a $Index, then the second animal's progeny are each $5 better than the first animal's progeny. Why half? Because if the Index is based upon Estimated Breeding Values (EBVs), then 1/2 is passed on to progeny. If the Index were based on EPDs (Expected Progeny Differences) then all of the Index would be transmitted to progeny. In short, EPD = 1/2 EBV (if the trait is the same one)!

This property of $Indexes can be useful for determining the economic value of the genetic merit of an animal for commercial production. If each animal had produced 100 progeny, then the second animal should have produced $500 more than the first one. The following table illustrates this example with 2 bulls. The second bull is 10 EBV index points better than the first. The figures in the columns beginning with "$" show the additional $ earned from Bull B over Bull A. Note that this only compares these 2 bulls; Bull A could be an excellent bull and already much better than average (you could do this comparison with the breed average Index value also!).

Why the differences? In our example, the second animal might be genetically superior for carcase traits, or grow faster, or his daughters may lactate better or produce more lambs (if he were a ram). There are lots of reasons why the genetics of an animal may result in superior performance and therefore profitability, so it isn't hard to see why genetic selection works.

In the Example population in X'Aim we've created a number of generations of selection using the new mating strategies with Index. Check out the new table of reports with summaries of the mating list easily comparable from report to report. The "Performer" strategy should result in the most genetic gain. Try it yourself to see how you can have different amounts of genetic gain on Index, progeny inbreeding and coancestry.

Being on the "Elite" plan gives you full access to genetic selection tools including Index. If you're not yet on an "Elite" plan you can still check out the new features including Index on the Quick Tour page on our website.