Selected Websites

Aggrey SE; Kroetzl H; Foelsch DW (1990). Behaviour of laying hens during induced moulting in three different production systems. Applied Animal Behaviour Science 25(1/2): 97-105.

Swiss Federal Institute of Technology, Zurich, Switzerland

NAL Call Number: QL750.A6

This work is a critical investigation of how methods of moulting are practiced by farmers. Dekalb hens were fasted with a reduced photoperiod to induce moult and hence lengthen the total egg laying period in three housing systems, namely wire floor, multifloor (globovolg) and battery cages. The behaviour of the hens was compared with their behaviour during the production period. The hens were frustrated at the time of feed deprivation, leading to increases in object pecking, locomotion and negative social interaction activities in the wire floor and globovolg systems. The behaviour of hens in cages during both production and moulting periods did not show any changes. At 4 days of fasting, resting activity dominated and during the moulting period (when new feathers were pushing out old feathers), the hens were almost inactive.

Descriptors: hens, molting, fasting, photoperiod, locomotion, agonistic behavior, chicken housing

            Copyright© 2002, CAB International


Avrutina AYa; Shinkareva VP; Vol'pe NO; Frolova EG (1976). Reaction of the adrenal system of the laying hen to the stress of starvation. [Reaktsiya adrenalovoi sistemy kur-nesushek na stress golodaniya.] Doklady Vsesoyuznoi Ordena Lenina Akademii Sel'skokhozyaistvennykh Nauk (Proceedings of the Lenin Academy of Agricultural Sciences) (No. 4): 33-34.

Vsesoyuznyi –I inst. razvedeniya I genetiki Sel'skokhozyaistvennykh zhivotnykh, USSR

            NAL Call Number: 20 Ak1

Leghorn hens were fed on a complete dry diet; daily egg production was measured. During the month before testing, sexual activity of the hens was assessed by mean frequency of mating during 24 h for 3 days. By age 14 months, the hens were subjected to starvation for 10 days, which induced moulting, then feed was reintroduced gradually. For the 10 days before starvation egg yield was, on average, 45.5%; on days 5 and 8 of starvation, yields were 14.3 and 0.93%, and by day 9 nil. Loss of weight was 15 to 20%. Plasma corticosterone was 7.99 plus or minus 0.45 mu g/100 ml before, on day 2 of starvation rose by 7.9% and by day 10 had dropped to 1.61 plus or minus 0.205 mu g/100 ml. During refeeding, the hormone concentration rose to 5.97 plus or minus 0.545 mu g/100 ml. In high-yielding hens with high sexual activity and in those with increased functional activity of the adrenals, compared with low-yielding hens and those with subdued sexual activity, there was a less sharp increase in corticosterone on day 2 of starvation. The findings could be used in selection of highly productive, stress-resistant lines of hens.

Descriptors: hens, starvation, corticosterone

            Copyright© 2002, CAB International


Barnett JL; Newman EA (1997). Review of welfare research in the laying hen and the research and management implications for the Australian egg industry. Australian Journal of Agricultural Research 48(4): 385-402.

Victorian Institute of Animal Science, Vic., Australia.

NAL Call Number: 23 Au783

Descriptors: hens, animal welfare, battery husbandry, battery cages, animal health, debeaking, perches, enrichment, molting, restricted feeding, environmental temperature, handling, transport, slaughter, occupational health, farm workers, poultry industry, literature reviews, alternative cage systems, beak trimming, environmental enrichment


Eskeland B (1981). Anatomical modifications and induced moulting: effects of beak trimming [laying hens, pens, population density, group size, behaviour]. First European symposium on poultry welfare: Report of proceedings, Soerensen LY (ed.), World Poultry Science Association: Copenhagen (Denmark), p.193-200. ISBN: 87-88162-00-1

Norges Landbrukshoegskole, Aas. Dept. of Poultry and Fur Animals

            NAL Call Number: HD9437 E9 1981


Gentle MJ; Breward J (1981). Anatomical modifications and induced moulting: the anatomy of the beak [chicken, trimming, Herbst corpuscle, Grandry corpuscle, taste buds]. First European symposium on poultry welfare: Report of proceedings, Soerensen LY (ed.), World Poultry Science Association: Copenhagen (Denmark), p.185-189. ISBN: 87-88162-00-1

Agricultural Research Council, Roslin, Midlothian, UK. Poultry Research Centre.

            NAL Call Number: HD9437 E9 1981


Gildersleeve RP; Johnson WA; Satterlee DG; Scott TR (1979). Daily rhythms of plasma corticosterone in hens during production and before a forced molt. Poultry Science 58(4): 1061.

Poultry Science Dep., Louisiana State Univ., Baton Rouge, LA 70803, USA.

            NAL Call Number: 47.8 Am33P

Study was of plasma corticosterone in laying hens force-moulted by deprivation of feed. Plasma corticosterone was reduced in hens allowed short daily photoperiods, 6 h light daily. In hens allowed 19 h of light daily (LH) the rhythm of plasma corticosterone values during 48 h tended to have 4 peaks. LH hens seemed to have an indistinct rhythm of plasma corticosterone.

Descriptors: corticosterone, blood plasma, hens

            Copyright© 2002, CAB International


Hoshino S; Suzuki M; Kakegawa T; Imai K; Wakita M; Kobayashi Y; Yamada Y (1988). Changes in plasma thyroid hormones, luteinizing hormone (LH), estradiol, progesterone and corticosterone of laying hens during a forced molt. Comparative Biochemistry and Physiology. A: Comparative Physiology 90(2): 355-359.

NAL Call Number: QP1.C6

Descriptors: hens, blood plasma, thyroid hormones, LH, estradiol, progesterone, corticosterone, molt


Hussein AS (1996). Induced moulting procedures in laying fowl. World's Poultry Science Journal 52 (2): 175-187.

Department of Animal Production, Faculty of Agricultural Sciences, United Arab Emirates University, P.O. Box 17555, Al-Ain, United Arab Emirates.

            NAL Call Number: 47.8 W89

Several methods of inducing moulting in laying hens are reviewed. Such methods are used to recycle laying hens, the majority of which require an optimum weight loss of 25-30% to achieve maximum egg production during the post-moulting period. The conventional feed restriction procedure is most often used in the egg industry because it is a simple, practical and economical technique that can be used in combination with light and/or water restriction. Mineral-induced moulting procedures, such as the use of high levels of either aluminum in the form of a soluble salt or dietary zinc, have also been used successfully. In addition, low concentrations of dietary Zn combined with a low-calcium diet have also induced moulting in laying hens. The use of low-sodium diets has also been as successful as the conventional feed restriction technique. Mineral-induced moulting procedures produce similar results to the conventional feed restriction techniques in post-moulting egg production, but with lower mortality rates; however, some of these procedures may not yet be practical for use in the egg industry. Hormone-induced moulting is another method and involves the use of the gonadotropin-releasing hormone agonist. It has an advantage over the conventional feed restriction procedure in that it does not require severe initial body weight loss to attain maximum egg production in the post-moulting period.

Descriptors: hens, molting, induction, weight losses, egg production, restricted feeding, mineral excess, aluminum, zinc, mineral deficiencies, calcium, sodium, GnRH, animal welfare, literature reviews


Jensen JF (1981). Anatomical modifications and induced moulting: [egg-laying hens, egg-laying capacity, control of diseases, control of environment]. First European symposium on poultry welfare: Report of proceedings, Soerensen LY (ed.), World Poultry Science Association: Copenhagen (Denmark), p.165-173. ISBN: 87-88162-00-1

Statens Husdyrbrugsforsoeg, Copenhagen, Denmark. Afdeling for Fjerkrae og Kaniner

            NAL Call Number: HD9437 E9 1981


Karunajeewa H (1987). A review of current poultry feeding systems and their potential acceptability to animal welfarists. World's Poultry Science Journal 43(1): 20-32.

Dep. Agric. Rural Affairs, Animal Res. Inst., Werribee, Victoria 3030, Australia

            NAL Call Number: 47.8 W89

Descriptors: chicken, barley, protein, feed intake, growth, induced molting


Luk'yanov V; Baidevlyatov A; Tsinovyi V; Ol'khovik L; Kuznetsov M (1976). A study of stress associated with the induction of moult in laying hens. [Ob otsenke stressa prinuditel'noi lin'ki u kur.] Ptitsevodstvo (No. 8): 17-19.

Ukrainskii nauchno-issledovatel'skii institut ptitsevodstvo, Kiev, Ukrainskaya SSR, USSR.

            NAL Call Number: Z5074 P8R4

Trials were carried out on 18,000 laying hens with moult induced by (I) deprivation of food and water, (ii) deprivation of calcium, (iii) oral administration of "Evertas" (metallibure analogue), (iv) injection of testosterone and thyroxine. Methods (I) and (ii) induced a moult after 10-15 days, lasting for 20-50 days. A general loss in weight was observed 10-40 days after the start of treatment. Water deprivation reduced eggshell thickness. Method (iii) caused inappetence, loss of weight and depression. These effects lasted for about 50 days. The use of hormones (method iv) caused marked depression; many treated birds adopted a "penguin" stance, and the depression lasted about 3-4 days. The greatest mortality in the first month after treatment was in birds treated by methods (I) and (ii). Mortality was much lower in birds treated with "Evertas" or with hormones. All methods of malt induction caused initially a decrease in blood calcium, cholesterol, lipoproteins and ribonuclease activity; and an increase in blood proteins. During the later stages of moult these values returned to normal.

Descriptors: egg production, stress, hens, moulting

            Copyright© 2002, CAB International


Novidov BG; Garmatina SM; Danilova OV (1980). Neuroendocrine mechanisms of stressor molting in birds. Doklady Biological Sciences, Proceedings of the Academy of Sciences of the USSR, Biological Sciences Sections 247(1/6): 1042-1044.

            NAL Call Number: 511 P444AEB

Descriptors: hens; hormonal control; moulting


Rolon A; Buhr RJ; Cunningham DL (1993). Twenty-four-hour feed withdrawal and limited feeding as alternative methods for induction of molt in laying hens. Poultry Science 72(5): 776-785.

The University of Georgia, Athens, GA

NAL Call Number: 47.8 AM33P

Alternative molting methods involving shorter periods of feed withdrawal and feeding a low-density and low-energy "molt diet" were compared to conventionally molted (8-day feed removal) and nonmolted hens. Alternative molt methods consisted of feeding the molt diet for 28 days for ad libitum intake, daily limited, or alternate-day limited (feeding every other day). Egg production, egg weight, specific gravity, body weight, feed intake, and mortality were recorded for 31 wk from the start of the molt (4 wk molt, 1 wk prelay, and 26 wk postmolt). Economic variables (feed cost, egg value, income over feed costs per hen housed) were compared between molting methods. Hens provided ad libitum access to the molt diet produced more eggs during the molt period than hens molted by other methods. Total egg production and income (egg value minus feed cost) were comparable among all molting methods and exceeded the values for nonmolted control hens. Income per hen housed was $2.20 for nonmolted control, $2.87 for the conventional, $2.92 for ad libitum, $2.81 for daily limited, and $2.97 for the alternate-day limited hens. These results indicate that alternative molting methods involving periods of feed withdrawal of 24 h or less can be as economically effective as conventional methods using longer periods of feed withdrawal.

Descriptors: hens, restricted feeding, diet, molt, metabolizable energy, body weight, egg weight, egg production, mortality, feed intake, production costs, income, animal welfare, feed costs


Rozak; Ungerer T; Nasution SH (1992). Effect of stress from feed and drinkwater restriction on hormone level and body resistance reaction of chickens. [Pengaruh stress pengurangan makanan dan minuman terhadap kadar hormon dan kadar reaksi alat pertahanan tubuh]. Gema Penelitian 5(1): 17.

            NAL Call Number: S471 I5G45

Descriptors: chickens, feed consumption, starvation, water deprivation, forced moulting, stress, antibodies, leukocytes, erythrocytes , biological development, birds, blood, blood cells, cells, consumption, domestic animals, domesticated birds, feeding, galliformes, immunological factors, immunology, livestock, moulting, poultry


Ruszler PL (1998). Health and husbandry considerations of induced molting. Poultry Science 77(12): 1789-1793.

Virginia Polytechnic Institute and State University, Blacksburg, VA.

NAL Call Number: 47.8 Am33P

There have been many methods proposed to induce molting. Some worked very well in practice, but others were detrimental to the health and welfare of the hens. The most effective methods use some level of feed restriction and daylength manipulation to reduce body weight (Hansen, 1966; Ruszler, 1974, 1984, 1996; Swanson and Bell, 1974; Brake and Carey, 1983). Weight reduction is necessary for rest and rejuvenation of body tissues. Other methods evaluated incorporated dietary imbalances using either zinc, iodine, or sodium. Pharmaceuticals have been used but have not been cost effective. In recent years there have been those who question whether molting techniques are humane. Therefore, interest has been heightened in alternate methods to induce molting. Research reported to date has been inadequate to accurately determine which methods of induced molting are the least stressful, if they in fact, cause any more stress than that experienced by the hen during a natural molt. The three or four most highly refined methods being used commercially are not generally detrimental to the health and welfare of today's laying hen, provided that they are managed in accordance with proper husbandry practices.

Descriptors: hens, molting, starvation, duration, animal welfare, restricted feeding, protein intake, weight losses, light regime, oyster shells, calcium, laying performance


Ruszler PL; Minear LR (1997). Comparison of induced molts using periods of four vs ten days feed withdrawal. Poultry Science 76(Suppl. 1): 104.

Dep. Animal Poultry Sci., Virginia Tech., Blacksburg, Virginia 24061

            NAL Call Number: 47.8 Am33P

Descriptors: body weight loss, commercial flocks, four versus ten days feed withdrawal, induced molts comparison, light exposure


Simonsen HB (1981). Anatomical modifications and induced moulting: welfare aspects related to number of laying periods of hens [ethics, legislation, disease, mortality, physiology, behaviour]. First European symposium on poultry welfare: Report of proceedings, Soerensen LY (ed.), World Poultry Science Association: Copenhagen (Denmark), p.177-182. ISBN: 87-88162-00-1

Kongelige Veterinaer- og Landbohoejskole, Copenhagen, Denmark. Afdeling for Retsmedicin

            NAL Call Number: HD9437 E9 1981


Taylor AA; Hurnik JF (1996). The long-term productivity of hens housed in battery cages and an aviary. Poultry Science 75(1): 47-51.

University of Guelph, ON, Canada.

NAL Call Number: 47.8 Am33P

This study examined the long-term effects of housing system on several aspects of laying hen production. At 19 wks of age, 336 White Leghorn hens were placed, 3 birds per cage, into battery cages; 437 birds were assigned to an aviary with communal nests, ambulation areas, and three raised tiers with feeders and drinkers. Family groups were split between the two housing systems. The hens were housed in such a manner for over 3 yr (until the end of the 168th wk of age), with forced molts between 66 and 74 and between 119 and 125 wk of age. Feed consumption and conversion, egg weight, eggshell deformation, and hen-day productivity were assessed monthly in both systems. Although feed consumption and conversion tended to be higher in the aviary throughout the study, these variables differed significantly due to housing system only in Year 2 (P = 0.04). There were no differences in egg weight (P = 0.7), eggshell deformation (P = 0.85), egg cracking during shaking (P = 0.34), total hen-day productivity (P = 0.55), or egg mass produced per hen per month (P = 0.4). Although aviary systems have been criticized for egg losses due to floor laying, only 2.5% of eggs in the current study were laid on the floor in Year 1, and 0.3% in Years 2 and 3;1.7% across all years. Hen mortality was variable across production and molt periods, and did not differ due to housing system (P > 0.05). The results of this study confirm that hen productivity in well-managed alternative housing systems can compare favorably with that in battery cages.

Descriptors: hens, battery cages, aviaries, feed intake, feed conversion, egg weight, egg shell defects, laying performance, mortality, egg mass, animal welfare, unrestricted feeding


Vermaut S; de Coninck K; Onagbesan O; Flo G; Cokelaere M; Decuypere E (1998). A jojoba-rich diet as a new forced molting method in poultry. Journal of Applied Poultry Research 7(3): 239-246.

Laboratory of Physiology and Immunology of Domestic Animals, Katholieke Universiteit Leuven, K. Mercierlaan 92, B-3001 Heverlee, Belgium

            NAL Call Number: SF481.J68

The use of jojoba meal for inducing molting, based on feed restriction was studied. Broiler breeder chickens were force-moulted by 12% jojoba meal supplementation in the diet resulting in higher egg production than before moulting. This percentage of jojoba meal restricted feed intake to a level similar to that of chickens moulted by a well-established qualitative force-moulting method (UK Agricultural Development and Advisory Service's, involving a quantitative feed restriction of wheat only, combined with a reduced photoperiod). The regression of the oviduct during the moulting period is probably due to the severe feed restriction itself, and is not a toxic effect of jojoba meal. The oviduct regrew completely after withdrawal of jojoba meal. Jojoba meal thus has no irreversible inhibitory effect on regrowth of the oviduct of adult broiler breeders after moulting, whereas in growing pullets, jojoba meal is known to produce an irreversible inhibition of the oviduct development, resulting in no egg laying.

Descriptors: chickens, molting, restricted feeding, jojoba, animal welfare, anorexiants, chemical composition, body weight, laying performance, oviducts, length, weight, ovaries, photoperiod, feed intake


Wakeling DE (1977). Induced moulting-a review of the literature, current practice and areas for further research. World's Poultry Science Journal 33(1): 12-20.

ADAS, MAFF, Starcross, Devon, UK.

            NAL Call Number: 47.8 W89

Descriptors: hens, animal physiology, reviews, molting, molt induction, poultry


Wang G; Zhu J; Zhao W; Yan J; Huang D; Li Z (1995). Endocrine characteristics of moult induced by GnRH agonist in laying fowls. Jiangsu Journal of Agricultural Sciences 11(1): 36-39.

Institute of the Application of Atomic Energy in Agriculture, Jiangsu Academy of Agricultural Science, Nanjing 210014, China

            NAL Call Number: S539.5 C55

In hens treated with a GnRH agonist, plasma thyroxine concentration was significantly higher than in untreated, control hens, but there was no significant difference in triiodothyronine concentration. Plasma progesterone concentration was significantly lower, and oestradiol concentration was significantly higher, in treated than in control birds. Treatment with the agonist resulted in suspension of laying for 22 days. At the start of the next laying season, laying rate and egg weight did not differ significantly between treated and control birds.

Descriptors: moult, induction, GnRH, egg production, egg weight, thyroid hormones, sex hormones


Webster AB (2000). Behavior of White Leghorn laying hens after withdrawal of feed. Poultry Science 79(2): 192-200.

NAL Call Number: 47.8 Am33P

To approximate a commercially induced molt, feed was withdrawn (FW) from Hy-Line W-36 hens (65-wk-old) until they lost 35% of their initial body weight. Behaviors of 36 FW hens and 36 control hens were video recorded on Days 1 to 3, 8 to 10, and 19 to 21 of FW, when FW hens reached 15, 25, and 35% body weight loss. The FW hens then were fed a pullet grower ration until Day 28 after the start of FW, whereupon they were provided a layer ration. Second cycle production of FW hens to 40 wk postmolt initiation averaged 15.5 dozen eggs/hen housed. The FW hens manifested increased aggression on the first d of FW, perhaps indicative of frustration, and then exhibited increased standing, head movement, and nonnutritive pecking on Day 2, followed by reduction of these actions on Day 3. Resting behavior was observed 24 and 40% of the time for FW hens on Days 8 to 10 and 19 to 21 of the FW period, respectively. Nonnutritive pecking was higher for FW hens than for control hens throughout the FW period. Preening was more frequent for FW hens on Days 8 to 10, probably due to skin sensitivity near the start of feather push out, which began on Day 11. Behavior during the feed withdrawal period was consistent with conservation of bodily reserves, but FW hens never lost their capability for alertness and reactivity. The FW hens had significantly lower mortality during the study than control hens (2 vs 12%, respectively).

Descriptors: hens, body weight, starvation, weight losses, molting, mortality, laying performance, animal behavior, rest, aggressive behavior, preening, pecking

Selected Websites

American Veterinary Medical Association Position on Induced Molting in Layer Hens


Canadian Veterinary Medical Association Animal Welfare Position Statement on Forced Molting of Chickens


Food Marketing Institute (FMI) and the National Council of Chain Restaurants (NCCR) Animal Welfare Program June 2002 Report


Force-molting Studies with an Emphasis on Animal Welfare at Cornell University


Forced Molting of Laying Birds


Induced Molting Resolution Fails, but Delegate Support for Alternatives Grows. Journal of the American Veterinary Medical Association, September 1, 2001


McDonald's Corporation Laying Hens Guidelines


Molting, Bird Density, and Animal Welfare by Ken W. Koelkebeck, University of Illinois


Research on Alternative Molting Methods California Poultry Letter September/October 2001, Cooperative Extension Service, University of California at Davis


Wendy’s Animal Welfare Program Fact Sheet: Chicken Supplier Requirement



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Updated April 4, 2005