RECENT ADVANCES IN INDUCED MOLTING

Molt induction methods that produce a complete cessation of lay, repro ductive involution for several days, and loss of nearly 50% of the pri mary feathers are the most successful. Feed deprivation and high level s of dietary zinc have proven to be the most consistent methods availa ble. Calcium appears to play a pivotal role in molt induction as calci um carbonate feeding prolongs ovulation during the initial stages of a n induced molt and dietary zinc has been shown to interfere with calci um-related metabolic activities at the level of the ovary. The primary site of action of feed deprivation appears to be at the level of the hypothalamic-hypophyseal axis, where calcium is involved in many endoc rine pathways. The physiological basis of postmolt rejuvenation has be en related to the extent of ovarian and oviducal involution. Evidence suggests that restructuring of receptor or membrane functions in the o viduct is the basis for rejuvenation. A body weight loss of about 30% appears to be necessary for appropriate restructuring of the shell gla nd.