The noise level is often measured in decibels (dB), and the critical level at which chickens are considered “stressed” is thought to be 85 dB or above, and the stress would be more drastic with prolonged time of exposure to noise. In this case, feed intake performance would be reduced by about 15-25% due to changes in neural and endocrine functions which affect retention time and rate of passage of feed through the GI tract, thereby affecting the ability of the bird to ingest new batches of feed.