Why do viral respiratory infections like Infectious Bronchitis (IB) cause watery, runnier albumen (low Haugh units)?

Infectious Bronchitis (IB) is a highly contagious, acute viral disease caused by a coronavirus. While primarily known for respiratory signs, nephropathogenic and oviductotropic strains of IB (like the QX or D274 strains) have a powerful tropism for the reproductive tract of brown layers. The virus replicates in the ciliated epithelial cells of the magnum, causing severe cellular necrosis and deciliation. Because the magnum is responsible for secreting the high-viscosity ovomucin protein gel that forms the thick albumen, this cellular destruction prevents the proper synthesis of thick egg white. Consequently, eggs laid by IB-infected hens have highly watery, runnier albumen, with Haugh units dropping below 50 (severely degrading freshness ratings). The chalaza also weakens, letting the yolk float. These watery eggs are unsellable to high-end retailers. Farmers can browse diagnostic pathology in the Poultry Encyclopedia, buy multi-strain IB vaccines and sanitizers on Poultry Plaza, track daily egg prices on Poultry Rates, and trade on Murghi Mandi.