The quality of the navel is an important quality control point in the assessment of day old chicks. As the navel is a pathway for bacteria, a good closure of the navel is essential for chick quality.
There are many ways to classify the quality of the navel of a day old chick. A common method is to blow at the navel and in this way spread the feathers around it, which allows a visual score. Although this is a good method for scoring a limited number of chicks, it has it's limitations when more chicks need to be evaluated.
A fast method is to easiest way to judge the quality of the navel of a day old chick is by feeling the navel with the index finger. When a finger is rubbed over the navel, one can easily feel if the navel is flat, if there is a little sharp object stucked in the navel, of if there is a bigger object hanging out from the navel.
A good quality navel can hardly be felt by rubbing a finger over it, as it is almost flat or only sligthly rounded. A swollen navel has often a small hard piece of material in it, which can be felt quite well by rubbing it. This hard piece of material is a piece of dried up membrane, which means that the membrane was not totally taken up before the navel was closed, trapping the last piece in the closing navel. Although chicks with this quality navel can be delivered, it shold not be considered as a good navel qualitty.
When the material sticking out of the navel is bigger than approximately 2 mm, the navel is poorly closed and these chicks should not be classified as a deliverable chick.
String navels are a special category, as the navel doesnt feel as a hard piece of material sticking out. A string navel can be felt well by rubbing a finger over the navel as well, but it feels indeed as a little string.under ones finger. Chicks with string navels have an increased change to die from navel yolk sac mortality and should not be considered as a deliverable chick.