Which diseases in laying hens cause eggshell color to turn white or pale?

Newcastle disease, egg drop syndrome, infectious bronchitis, colibacillosis, white crown disease and other diseases can noticeably turn eggshell color white. On the one hand, after pathogens invade the chicken's body, they cause pathological changes in the reproductive system, reducing the function of the glands in the chicken's body to synthesize calcium and pigment; at the same time, after the disease, the chicken's feed intake drops, digestive function declines, the absorption of calcium and phosphorus decreases, and it also causes the loss of copper, zinc and manganese, ultimately leading to a deficiency of eggshell components and the appearance of a large number of white-shelled eggs. On the premise of eliminating the cause, raising the nutritional level of the feed and appropriately increasing the content of vitamins A, D, E and C has a clear therapeutic effect on improving egg color.