Physiological changes in caged layers during a forced molt. 1. Body temperature and selected blood constituents

The effects of forced molting on body temperature and selected blood constituents were studied. Caged layers, reared under commercial conditions, were force molted successively at 72 and 104 weeks of age. This was accomplished by removing feed for up to 12 days and water for up to 3 days while simultaneously reducing the day length to 10 hr or less. This procedure resulted in a cessation of egg production within one week of the initiation of feed removal. There was a significant increase in body temperature during feather loss and renewal. Packed cell volume and hemoglobin increased significantly immediately upon removal of feed and water and remained elevated above control levels for the duration of the pause in egg production, while plasma total calcium, and inorganic phosphate decreased significantly during the corresponding period. Plasma total protein and plasma glucose did not exhibit consistent trends. Body temperature and the levels of the measured plasma consituents returned to normal levels upon the resumption of egg production.