Have you wondered why your egg belts "stretch" and then appear to "shrink"? This is actually expected, at least to some degree. Let's explore why.
Most egg belts are woven polypropylene fabric. Just like any fabric, when exposed to a load, it will stretch. This is illustrated in the diagram below. How much it stretches under that load is a function of how the individual fibers are manufactured and the process used to weave the fibers into a fabric. If your facility is in an area of the country where there are extreme temperature and humidity changes throughout the year, that might also lead to variation in how much stretch you will see.
When the conveyor stops moving, the load is reduced, and the fabric will appear to "shrink". But in fact, it is just the fabric recovering its shape. If you waited long enough, the belt would almost completely recover to its original length if all the load is removed. True "shrinkage" would only occur if the egg belt was exposed to very high temperatures that are associated with the processing temperature of the fibers themselves. This could never happen in a barn so it is not a factor.
One of the advantages with Breeders Poultry Belts vs. competitive suppliers is that we use proprietary fibers and weaving processes that are engineered to minimize both stretch and "shrinkage". This reduces installation cost and maximizes production.