Production Type Index (PTI) is a measure combining both yield and type evaluations into a single number. The higher the number, the more likely improvements will take place by using those genetics. PTIs will only be calculated for animals with both yield and type evaluations.
These indexes normalize evaluation data and act as predictors of genetic transmissibility. There are 2 flavors of indexes:
* 2:1 - production weighted over type
* 1:2 - type weighted over production
The Estimated Transmitting Ability (ETA) is an index that hopes to predict the genetic potential of offspring based on the PTIs of the sire and dam (or dam's sire). The higher the number, the more genetic potential. PTIs must be available to make this calculation.
Okay-- PTI is a number that is a combination of both appraisal scores and milk test info.
The higher the number, the better chance you have of making improvements.
In the 2:1 ratio, production is weighted over type. 1:2 is type over production. If I want to add a lot of type to my program, I look for animals with a high 1:2 number. If I am looking to add milk, I look at the 2:1 numbers. Optimally, both numbers are high.
ETA is what you HOPE a buck will pass on, based on his sire and dam's PTI numbers. The higher the number, the greater chance for excellent offspring.