Letter from Ian J.H. Duncan, BSc., PhD. Re:
Forced Molting Violates California's Animal Cruelty Laws

Deputy Attorney General Gregory Gonot
P.O. Box 944255,
Sacramento, CA,

13th November 2000

Dear Deputy Attorney General Gregory Gonot,

Opinion No. 00-1004

I am writing in response to your request for comment on the following question:

Is it a violation of the State's animal cruelty laws to engage in "forced molting" in which food is withheld from chickens for 5 to 14 days in order to manipulate the hormones responsible for egg production and feather cover?

I have been carrying out research into poultry welfare since 1965 when I started working on my PhD on the topic of frustration in the fowl at Edinburgh University. From 1968 to 1988 I worked as Principal Scientific Officer at the AFRC Poultry Research Centre in Edinburgh on all aspects of poultry behavior and welfare. Since 1989, I have been Professor of Poultry Ethology at the University of Guelph and I also hold the University Chair in Animal Welfare. I have published more than 150 papers on poultry welfare in scientific journals and therefore feel qualified to comment on the practice of forced molting.

In my opinion, forced molting, by withdrawing feed from hens for between 5 and 14 days, causes extreme suffering and is a violation of your State's animal cruelty laws. Specifically it violates California Penal Code 597b, which states that "whoever fails to provide the animal with proper food, drink, shelter, is, for every such offense, guilty of a crime". Forced molting by means of feed or water deprivation has been banned in most European countries because it is considered a cruel practice.

Under natural conditions, domestic fowl are stimulated into lay by increasing day-length. This means that in the Spring, when day-length exceeds about 11½ hours, they start to lay eggs. If these eggs are fertile and are allowed to accumulate in a nest, they trigger the hen to switch from laying to incubating behaviour, when there are about 12 or 14 eggs present. The hen will then hatch the eggs and look after the chicks for a number of weeks. There may be time during the Summer for the hen to lay a second clutch of eggs and raise a second family of chicks. However, when day-length decreases below about 11 hours in the Fall, the hen will go out of reproductive condition, stop laying and go into a natural molt. Feathers are gradually replaced over most of the body surface and this is a relatively long process (Duncan, et al., 1978).

During the 21 days when the hen is incubating her eggs, her food intake is greatly decreased. However, she still leaves the nest once a day, consumes a small quantity of food, takes a small drink, defecates and sometimes preens and dustbathes (Duncan, et al., 1978). This reduction in food intake (or voluntary "fasting") during incubation has been used by the poultry industry to justify the practice of removing food for many days in order to force hens into a molt.

However, the two processes are completely different. In one, a change in hormone level brought about by a natural chain of events, results in a reduction in food intake. In the other, food is removed in order to bring about a change in hormone levels and force hens out of reproductive condition.

There are many examples of natural fasting in the animal kingdom. For example the Emperor penguin (Aptenodytes forstei), will go without food for several weeks while incubating its egg. The North American Black bear (Ursus americanus), will go without food while hibernating through the Winter. However, this does not justify removing food from these animals for several weeks when they are in captivity, and any zoo keeper who did so, would be prosecuted immediately. Of course, if penguins were incubating eggs or if Black bears were hibernating then they would not require food. Similarly, if laying hens went broody naturally, they would not require as much food. But this is not what happens during forced molting.

Commercial egg laying hens come into lay at about 20 weeks of age and are maintained in lay for a year by keeping the day-length long (greater than 11.5 hours). Modern strains of laying hen do not go broody and so in a laying year a hen will lay more than 300 eggs. However, after laying eggs for a year, egg production starts to fall, egg shell quality decreases, the bird's skeleton has been depleted of calcium through producing all these egg-shells and is fragile, and the hen is often overweight. If hens were then put on to short days, say of 8 hours, they would gradually go out of reproductive condition and would molt naturally.

However, natural molting is a slow process and within a flock of hens there would be a wide range of times for individual hens to complete the molt. Currently, the poultry industry is not prepared to accept this extended loss of production. Therefore, at about 74 weeks of age, hens are sent to slaughter as "spent laying hens" (this happens commonly in Canada) or are "force molted", in order to speed up the molting process and get the hens back into reproductive condition for a second and sometimes a third laying year (this is the common practice in the U.S.).

Forced molting programs usually involve withholding feed for 10-14 days and simultaneously reducing day-length (North and Bell, 1990; Leeson and Summers, 1991). Forced molting shortens the period of non-production to about 8 weeks but results in a huge increase in stress and suffering.

A rather crude indicator of reduced welfare is increased mortality. During forced molting, mortality increases dramatically. Dr. Don Bell summarized molting results from 353 U.S. flocks during 1997 and 1998 and found that mortality typically doubled during the first week of molt, then doubled again during the second week (cited by Duncan and Mench, 2000)

However, even apart from mortality, the evidence suggests that hens suffer enormously during forced molting. Hunger is an extremely powerful motivation and chickens have evolved to forage and consume food throughout the day (Savory et al., 1978). Consequently, deprivation of food acts as a drastic stressor. Food deprivation results in a classical physiological stress response (Mench, 1992). Frustration of feeding leads to signs of extreme distress such as increased aggression (Duncan and Wood-Gush, 1971) and the formation of stereotyped pacing (Duncan and Wood-Gush, 1972). Extremely hungry birds also show stereotypic pecking at objects such as feeders (Kostal et al., 1992; Savory and Maros, 1993; Hocking et al., 1996). In an experiment in which hens were deprived of food for three days, Webster (1995) found that cage-pecking increased by a factor of three and feather pecking increased by a factor of eight. In a later study, designed to simulate forced molting, Webster (2000) deprived hens of feed for 21 days. Hens subjected to this deprivation at first showed increased aggression and non-nutritive pecking suggestive of severe frustration and extreme hunger, and later inactivity suggestive of debilitation (Duncan and Wood-Gush, 1971, 1972)

Withholding feed from hens for 10-14 days meets the biological definition of "starvation". European society has made the decision that this practice is cruel and inhumane and should be banned (Appleby et al., 1992). I am sure that North American society would also find this practice unacceptable. It would be completely unacceptable if carried out on any other class of farm livestock and, in fact, several Canadian swine producers were prosecuted for abandoning their pigs when the bottom fell out of the pork market two years ago.

In conclusion, and after reviewing all the physiological and behavioral evidence, it is my opinion that forced molting is a cruel practice that leads to severe suffering in laying hens.

The Californian Attorney General's Office is to be commended for investigating this practice. I look forward to hearing the outcome and will be pleased to provide further information if you require it.

Yours sincerely,

Ian J.H. Duncan, BSc., PhD.,
Professor of Poultry Ethology
Chair in Animal Welfare


Appleby, M.C., Hughes, B.O. and Elson, H.A., 1992. Poultry Production Systems: Behaviour, Management and Welfare. CAB International, Wallingford, UK.

Duncan, I.J.H. and Mench, J.A., 2000. Does hunger hurt? Poultry Science, 79:934.

Duncan, I.J.H. and Wood-Gush, D.G.M., 1971. Frustration and aggression in the domestic fowl. Animal Behaviour, 19: 500-504.

Duncan, I.J.H. and Wood-Gush, D.G.M., 1972. Thwarting of feeding behaviour in the domestic fowl. Animal Behaviour, 20: 444-451.

Duncan, I.J.H., Savory, C.J. and Wood-Gush, D.G.M., 1978. Observations on the reproductive behaviour of domestic fowl in the wild. Applied Animal Ethology, 4: 29-42.

Hocking, P.M., Maxwell, M.H. and Mitchell, M.A., 1996. Relationship between the degree of food restriction and welfare indices in broiler breeder females. British Poultry Science, 37:263-278.

Kostal, L., Savory, C.J. and Hughes, B.O., 1992. Diurnal and individual variation in behaviour of restricted-fed broiler breeders. Applied Animal Behaviour Science, 32:361-374.

Leeson, S. and Summers, J.D., 1991. Commercial Poultry Nutrition. University Books, Guelph, Canada.

Mench, J.A., 1992. The welfare of poultry in modern production systems. Poultry Science Review, 4:107-128.

North, M.O. and Bell, D.D., 1990. Commercial Chicken Production Manual. Chapman and Hall, New York, USA.

Savory, C.J. and Maros, K., 1993. Influence of degree of food restriction, age and time of day on behaviour of broiler breeder chickens. Behavioural Processes, 29:179-190.

Savory, C.J., Wood-Gush, D.G.M. and Duncan, I.J.H., 1978. Feeding behaviour in a population of domestic fowl in the wild. Applied Animal Ethology, 4: 13-27.

Webster, A.B., 1995. Immediate and subsequent effects of a short fast on the behavior of laying hens. Applied Animal Behaviour Science, 45:255-266.

Webster, A.B., 2000. Behavior of White Leghorn laying hens after withdrawl of feed. Poultry Science, 79:192-200.

United Poultry Concerns, Inc.
PO Box 150
Machipongo, VA 23405-0150
FAX: 757-678-5070

(Ian J.H. Duncan Letter: Forced Molting Violates California's Animal Cruelty Laws)