Several successful methods of inducing moulting have been used to recy
cle laying hens, the majority of which require an optimum weight loss
of 25-30% to achieve maximum egg production during the post-moulting p
eriod. The conventional feed restriction procedure is most often used
in the egg industry because it is a simple, practical and economical t
echnique that can be used in combination with light and/or water restr
iction. Mineral-induced moulting procedures, such as the use of high l
evels of either aluminium in the form of a soluble salt or dietary zin
c, have also been used successfully. In addition, low levels of dietar
y zinc combined with a low calcium diet have also induced moulting in
laying hens. The use of low sodium diets has been equally as successfu
l as the conventional feed restriction technique as a means of inducin
g a moult. Although mineral-induced moulting procedures produce simila
r results to the conventional feed restriction techniques in post-moul
ting egg production, but with lower mortality rates, some of these pro
cedures may not yet be practical for use in the egg industry. Hormone-
induced moulting is another method and involves the use of the gonadot
ropin-releasing hormone (Gn-RH) agonist. It has an advantage over the
conventional feed restriction procedure in that it does not require se
vere initial body weight loss to attain maximum egg production in the
post-moulting period.