By Kiyimba Bruno
The goal of breeding chickens and turkeys and also pigs and cattle is to mate the best animals of a generation to produce the next generation.
But which ones are the best animals? The animals that perform best for the traits that the breeding company (actually its customers) finds important and likes to see most.
These traits can change over time, because customers ask for an animal with different qualities.
For years egg layers were selected for egg numbers, early maturity, peak production and persistency of lay and egg quality and color. At the same time selection attention was paid to the egg weight curve, feed conversion, body weight, hatchability and culls.
All these traits were considered more or less strongly depending on how they fit in the breeding goal.
To establish how good an animal is we have to measure and collect all kinds of data. Certain traits, like growth, can be measured on the animals themselves, but for many other traits, like potential egg production on males, that is not possible. In such cases the geneticist evaluates parents, half siblings and progeny. Based on all this collected data an animal is assigned a breeding value, which is an estimate of how good an animal is.