Non-Feed Withdrawal Molting
By A. Bruce Webster Extension Poultry Scientist, University of Georgia - Induced molting is an important practice for many egg companies in the United States because it minimizes costs associated with the growing of replacement pullets and disposal of spent flocks.
19 December 2005
4 minute read
Feed withdrawal for a specified time or until a certain body weight loss is reached has been
the traditional method because it is simple to implement and consistently produces the best results
in terms of second cycle egg production and egg quality. However, the feed deprivation required
to produce an effective induced molt raises animal welfare concerns The initiative by the United
Egg Producers (UEP) to encourage U.S. egg producers cease molting flocks by feed withdrawal has
led to the development of practical non-feed withdrawal molting programs which allow hens to eat
during the stage when egg production must be stopped. Information about these programs may be
obtained by contacting UEP (www.unitedegg.org).
In 1995, the United States Department of Agriculture Animal and Plant Health Inspection
Service (USDA APHIS) SE Pilot project reported that the percentage of eggs contaminated with
Salmonella enteritidis (SE) increased when flocks were molted by feed withdrawal. Subsequently,
the USDA APHIS National Animal Health Monitoring System Layers 99 study published in 2000
confirmed that isolation rates of SE were higher in feed withdrawal molted hens versus non-molted
hens in commercial flocks. Laboratory research showed that feed withdrawal makes hens much
more susceptible to colonization by Salmonella bacteria (Holt and Porter, 1992; Holt 1995).
It can
be concluded from these studies that, in SE positive flocks, molting hens by feed withdrawal can
increase SE contamination of the house environment, increase the number of hens infected with SE,
and increase the percentage of eggs contaminated with SE, at least for some time. Thus it is possible
for induced molting by feed withdrawal to increase risk of SE contaminated eggs entering the human
food supply.
Non-feed withdrawal molting does not appear to entail the same risk. There is laboratory
evidence that giving hens feed throughout an induced molt protects them from susceptibility to SE
infection (Holt et al. 1994; Woodward et al. 2005). Furthermore, a recent study on a commercial
farm has affirmed the protective effect of non-feed withdrawal molting against Salmonella
colonization of hens (Murase et al. 2004). This news is reason for producers to be encouraged as
they convert to non-feed withdrawal molting. Although the transition may involve some problem
solving and learning, not only will the egg industry offer greater animal welfare assurance by
moving away from induced molting by feed withdrawal, it also should be able to offer its customers
a greater assurance of food safety.
References
Holt, P.S. 1995. Horizontal transmission of Salmonella enteritidis in molted and unmolted laying chickens. Avian
Diseases 37:412-417.
Holt, P.S., and R.E. Porter, Jr. 1992. Microbiological and histopathological effects of an induced molt fasting procedure
on a Salmonella enteriditis infection in chickens. Avian Diseases 36:610-618.
Holt, P.S., R.J. Buhr, D.L. Cunningham, and R.E. Porter, Jr. 1994. Effect of two different molting procedures on a
Salmonella enteritidis infection. Poultry Science 73:1267-1275.
Murase, T., S. Miyahara, T. Sato, K. Otsuki, and P.S. Holt. 2004. Feeding of wheat middlings to commercial layers
as an alternative method to feed withdrawal that can be used to molt birds. Abstracts 2004 International Poultry
Scientific Forum, pp. 1782.
Woodward, C.L., Y.M. Kwon, L.F. Kubena, J.A. Byrd, R.W. Moore, D.J. Nisbet, and S.C. Ricke. 2005. Reduction of
Salmonella enterica serovar Enteritidis colonization and invasion by an alfalfa diet during molt in Leghorn
hens. Poultry Science 84:185-193.
Source: University of Georgia - Poultry Science - November 2005
