When incubation is optimal, the chicken embryo efficiently uses egg nutrients for development and growth. Common methods to evaluate chick quality are visual scoring, chick weight, Tona or Pasgar Score, and chick length at hatch.

Body weight is measured by weighing the whole chick. However, because chick weight includes an unknown amount of residual yolk, it does not express the development of the bird’s frame. A heavy chick can have a large residual yolk and a small yolk-free body mass. This embryo did not efficiently use the yolk for development and growth during the incubation process.

The Tona and Pasgar score evaluate different criteria such as down and appearance, navel area, legs, yolk sac, and activity. The Tona and Pasgar score evaluates primarily the last period of incubation. The criteria measured in the Tona and Pasgar score are therefore related to first week mortality, but do not predict subsequent field performance.

Chick length is a good practical method to predict chick development because it is positively related to yolk-free body mass at hatch. It evaluates the total incubation process and can predict subsequent performance. Chick length is a fast, repeatable, and non-destructive method to evaluate chick quality.

We recommend the use of the chick length in your Quality Analysis program. Routine chick length evaluation is a tool to monitor the quality and results of your incubation process. Ongoing chick length evaluation ensures that your chicks consistently have the optimum performance potential.