Litters are most easily identified using ear notches. Sometimes AI stations have boars that are closely related to each other, watch out for these when breeding the daughters of AI sires. The parentage of the boars is listed in the AI station catalog. Selection of AI sires is based on their performance records listed in the AI station catalog. The individual boar's performance, including average daily gain and backfat.
Individual performance is influenced by management as well as genetics.
Indexes comparing the individual's performance to those of other boars of similar age. These help to correct for management differences. These identify the improvement that can be expected by using these boars, while recognizing that the boar only provides half of the genetic material in the offspring. For example, a boar with an EPD of .05 for backfat should produce offspring that are 0.05 inches leaner than average. As well as individual performance records, boar catalogs contain information on the body type and parentage of the boars, and on whether they carry the stress gene.