Hormonal and Pharmaceutical Induced Molting

Selected Websites



Attia YA; Burke WH; Yamani KA (1993). Response of broiler breeder hens to forced molting by hormonal and dietary manipulations. Poultry Science 73(2): 245-258.

NAL Call Number: 47.8 Am33P

Experiments were conducted to compare dietary and hormonal techniques for molting broiler breeder hens. In the first experiment, production dropped to 5% 3 wk after hens were restricted to an intake of one half of their calculated energy requirement (FR). Egg production levels of hens given a single i.m. injection of the Lupron Depot®) formulation of leuprolide acetate (LA) in a dose intended to provide 10 microgram/kg BW per d for 30 d dropped to 9.5% whereas production dropped to 33% in hens receiving 5 microgram and was unchanged by 2.5 microgram. Postmolting fertility and hatchability of eggs from the FR and the 10-microgram LA groups were not different. In the second experiment, postinjection egg production, oviduct weight, and uterus weight were depressed, in a dose-related manner, when hens received 0, 10, or 22 microgram LA/kg per d. In a third experiment, egg production dropped to zero within 2 wk when hens were deprived of feed (FD) or deprived of feed and light (FD + LR), whereas it reached zero in 4 wk in hens fed only 30 g of wheat shorts per d (FR). Lupron Depot®) at a dose intended to deliver 30 microgram/kg BW per d, reduced egg production to 9.5% by the 3rd wk. Twenty-eight weeks postmolting, egg production ranged from 84 to 98 eggs per hen in the molted groups and 56 eggs per hen in the unmolted controls. Fertility ranged from 82.1% in the FD + LR groups to 69.8% in the unmolted controls, whereas chick production averaged 36, 50, 59, 60, and 68 chicks per hen in the unmolted controls and in hens molted by LA, FR, FD, or FD + LR, respectively.

Descriptors: hens, broilers, molting, feed intake, restricted feeding, fasting, light regime, molting hormones, laying performance, feed conversion, egg hatchability, weight, organs, egg shell, specific gravity, blood plasma, fatty acids, dosage ; Identifiers: leuprolide acetate


Burke WH; Attia YA (1994). Molting single comb White Leghorns with the use of the Lupron Depot formulation of leuprolide acetate. Poultry Science 73(8): 1226-1232.

NAL Call Number: 47.8 Am33P

Reproductive tract regression and cessation of egg production was induced in 80-wk-old Hy-line W36, strain hens by an i.m. injection of Lupron Depot at a dose calculated to release 60 microgram of leuprolide acetate (LA)/kg of BW for 30 d, by restriction of feed intake (FR) for 28 d, or by total feed deprivation (FD) for 7 d followed by feed restriction for 21 d. Egg production in LA and FD groups dropped to 24 and 19% in the first 7 d after initiation of the treatments and to 3.5 and 0% in the 2nd wk. Production of the FR group dropped to 38% during the 1st wk and to 1.7% in the 2nd wk. Production of both nutritionally deprived groups remained near zero through the 5th wk, whereas it increased to 8.2% in the LA group at that time. Hens injected with LA reached 50% production at about 37 vs 45 d for both nutritionally deprived groups. Egg production of control groups remained unchanged during this time. Shell characteristics did not differ significantly among the molted groups throughout most of the 16 wk of the experiment. However shell weight and shell weight per unit surface area of eggs from LA-treated hens were significantly (P less than or equal to .05) lower than those of FR, but not FD, hens at several times. Mean values for shell characteristics of eggs from unmolted hens were significantly lower than those of molted hens. There were no differences in albumen quality between any of the groups at any time. Hens molted by FR and FD lost 23 and 26% of their initial BW, respectively, 4 wk after the initiation of the experiment. There was no loss of weight in LA-treated or control hens.

Descriptors: hens, molting hormones, controlled release, LHRH, hormones, agonists, molting, restricted feeding, fasting, laying performance, ovaries, oviducts, weight, body weight, egg weight, egg albumen, egg quality, egg shell quality , leuprolide acetate


Dickerman RW; Bahr JM (1989). Molt induced by gonadotropin-releasing hormone agonist as a model for studying endocrine mechanisms of molting in laying hens. Poultry Science 68(10): 1402-1408.

University of Illinois, Urbana, IL

NAL Call Number: 47.8 AM33P

Descriptors: hens, gonadotropin releasing hormone, molt, molting, laying performance, weight losses, thyroxine, triiodothyronine, progesterone


Dvorak M; Sevcik B; Hyhlik J (1971). Effect of ICI 33828 on delay of egg production in pullets and on moulting in hens. [Overeni ucinku latky ICI 33828 na oddaleni snasky u kuric a prepereni nosnic.] Veterinaria SPOFA 13(5/6): 285-296.

            NAL Call Number: SF1 B5

Administration of 30 mg ICI 33828/kg food to 100 White Plymouth Rock pullets aged 130 days for 42 days inhibited egg production in 86.1%. After the withdrawal of treatment, egg production resumed immediately and in the 30 days following was higher than in untreated controls. The same dose was given to 264 White Leghorn pullets for 42 days. Over 134 days from the onset of treatment, egg production/pullet averaged 12.5, egg weight 47.5 g, hatchability of eggs set 87.1%, and hatchability of fertile eggs 90.0% v 15.8, 44.4 g, 87.4% and 90.7% resp. in 265 untreated controls. Administration of 100 mg ICI 33828/kg food to 950 White Leghorn hens for 4 days at the end of the 9th mth of lay induced moulting in 80.7% within 20 days.

Descriptors: metallibure, performance, egg production, egg weight, egg hatchability, egg fertility, moult, induction

            Copyright© 2002, CAB International


Edens FW; Thaxton JP (1988). Method of Inducing Birds to Molt Us Patent-4761398. August 2 1988. Official Gazzette of the U S Patent and Trademark Office Patents 1093 (1): 271.

Patent Number: US 4761398 Patent Classification: 514015000

            NAL Call Number: T223 A21

Descriptors: USCL-514-15, Hens, LHRH


Herremans M; Decuypere E; Chiasson RB (1988). Role of ovarian steroids in the control of moult induction in laying fowls. British Poultry Science 29(1): 125-136.

NAL Call Number: 47.8 B77

Descriptors: hens, molt, thyroxine, triiodothyronine, progesterone, estradiol, hormonal control, oviposition


Hoyle CM; Thaxton JP; Morgan GW; Schally AV (1988). Administration of microencapsulated 6-d tryptophan LHRH induces SCWL hens to molt. Poultry Science 67(SUPPL.1): 19.

            NAL Call Number: 47.8 AM33P

Descriptors: hormone, egg production, reproductive tract regression


Ishigaki R; Ohori Y; Ebisawa S; Kinbara K; Yamada Y; Nakajo S (1971). Forced molting by Metallibure (I.C.I. 33, 828), a nonsteroid anti-gonadotropic compound. 1. [Poultry] Japanese Poultry Science 8(2): 77-81.

NAL Call Number: 47.8 N57


Prochazka F; Hyhlik J; Sevcik B; Dvorak M (1971). Effect of the preparation VUFB 7319 on inhibition of egg production at the end of the laying period and on forced moulting. [Sledovani ucinku latky VUFB 7319 na preruseni snasky u nosnic na konci snaskoveho obdobi a na nucene prepereni.] Veterinaria SPOFA 13(5/6): 329-345.

Okresni veterinarni zarizeni, Pisek, Czechoslovakia.

            NAL Call Number: SF1 B5

100 mg VUFB/kg food was given to 1260 White Leghorns for 5-6 days at the end of the laying period (28-33% production). Egg production ceased within 11 days of the beginning of treatment; moulting started on day 5 and lasted for 20-35 days. 94% of hens moulted. A 50% resumption of egg production was recorded within 10 wk.

Descriptors: egg production, moult, progestogens, White Leghorn


Ruszler PL; Beane WL; Wolford JH (1984). Corticosterone and feed withdrawal as a forced rest technique in laying hens. Poultry Science 63(Suppl. 1): 35.

Department of Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061

            NAL Call Number: 47.8 AM33P


Sander H; Speck J (1976). Regulation of stress-free laying pauses using chlormadinone acetate. [Steuerung stressloser Legepausen mittels Chlormadinonacetat.] Deutsche Tierarztliche Wochenschrift 83(10): 451-455.

Tierarztliches Institut der Universitat Gottingen, 34 Gottingen, German Federal Republic.

            NAL Call Number: 41.8 D482

240 Arbor Acre hens, which had been in lay for 60 wk, were divided into 7 groups and installed in 3-bird cages. Three groups were given CAP for 10 days (10, 13 or 16 mg/kg food) and 3 groups for 20 days (7, 10 or 13 mg); a 7th group served as untreated controls. For the 6 treated groups resp., the laying paused lasted 15.1, 20.7, 23.1, 13.8, 25.8 and 26.0 days, laying rate in the 7th-15th wk after beginning of treatment was 55.2, 62.4, 58.5, 54.4, 59.1 and 62.9%, and egg weight averaged 58.9, 58.2, 57.9, 60.8, 57.7 and 59.2 g. In the control group, laying rate was 48.9% and egg weight averaged 59.5 g. Egg shell strength improved after CAP treatment.

Descriptors: moult, induction, laying performance, progestogens, CAP, stress, chlormadinone, egg production

            Copyright© 2002, CAB International


Schneider K-H; Gruhn K (1974). The effect of forced moult induced by staggered administration of methionine on egg production during the second year of laying. [Der Einfluss der Zwangsmauser unter Einsatz gestaffelter Methioningaben auf die Eiproduktion im zweiten Legejahr.] Tierzucht 28(2): 83-86.

Sektion Tierproduktion und Veterinarmedizin, Karl-Marx-Universitat, Leipzig, German Democratic Republic.

            NAL Call Number: 49 T443

Moulting was induced in half of 360 White Leghorn hens (A) and half of the hens were allowed to moult naturally (B). Mortality during the 2nd year of laying averaged 7.2% in group A v 14.1% in group B, body weight at the beginning and end of the 2nd year averaged 1798 and 1915 g resp. v 1894 and 1903 g, egg production/hen 195.2 v 186.2, and egg mass 11.8 v 11.2 kg. There were no significant differences between the groups in food conversion or egg shell thickness.

Descriptors: food conversion, egg shell thickness, methionine, moult, induction, egg production, mortality, body weight, egg mass, hens, moulting.


Sekimoto K; Imai K; Suzuki M; Takikawa H; Hoshino N; Totsuka K (1987). Thyroxine-induced molting and gonadal function of laying hens. Poultry Science 66(4): 752-756.

NAL Call Number: 47.8 AM33P

Descriptors: hens, thyroxine, molting, hormonal control, triiodothyronine, luteinizing hormone, progesterone, body weight, egg production


Sirotkin AV; Golubev AK (1983). Circadian changes in sensitivity of the chicken to exogenous hormones influencing molt and reproduction. Journal of Evolutionary Biochemistry and Physiology 19(6): 422-426. [Translated from: Zhurnal evoliutsionnoi biokhimii I fiziologii, p. 565-570. (QH345.Z5).]

NAL Call Number: QP1.J725


Stake PE; Frederickson TN; Okulicz W; Shippee RL; Fournier DJ (1979). Tamoxifen induced forced-rest/molt in laying hens. Poultry Science 58(4): 1111.

Dep. Nutritional Sciences, Univ. Connecticut, Storrs, CT 06268, USA

            NAL Call Number: 47.8 AM33P.

Descriptors: egg production, egg quality, moulting, hens, suppression


Szelenyi Z; Peczely P (1988). Thyroxin induced moult in domestic hen. Acta Physiologica Hungarica 72 (2) p143-149.

Laboratory of Geese Biochemistry, University of Agriculture, Godollo Hungary.

            NAL Call Number: QP1 A17

Two identical experiments were carried out in domestic hens treated with a lower (0.2 mg/animal) or a higher (0.4 mg/animal) dose of thyroxin (T4), for 21 consecutive days. The low dose diminished egg production, but did not result in moulting while the higher dose stopped egg laying on the 16th day and caused the loss of contour feathers from the 14th day on. The new plumage was completely developed in this group on about the 42th day. The plasma progesterone concentration showed an increase in both thyroxin treated groups, but is was only continuous and significant in the fowls treated with 0.4 mg T4. In this group the peak value of progesterone was synchronous with the most intensive feather loss. In the other group the tendency for increased levels of progesterone was of shorter duration and not significant. Plasma oestrone levels were depressed by the treatment in both groups and increased significantly only in the moulted fowls after administration of T4 was stopped. This increase may be associated with feather growth and regeneration of the oviduct. Plasma 17-beta oestradiol and testosterone concentrations did not change in the T4 treated groups. Plasma corticosterone concentration increased continuously only in the moulting animals. The results suggest that on one hand thyroxin has a role in the endocrine regulation of moulting and, on the other, that a thyroxin-progesterone synergism is of significance in the process.

Descriptors: Chickens--physiology--PH, Feathers--physiology--PH, Thyroxine --pharmacology--PD , Corticosterone--blood--BL, Estradiol--blood--BL, Estrone--blood--BL, Feathers--drug effects--DE, Oviposition--drug effects--DE, Reference Values , Testosterone--blood--BL


Szelenyi Z; Peczely P; Vadocz E (1988). Hormonal changes during forced moult induced by progesterone in domestic hen. Acta Physiologica Hungarica 71(1): 69-75.

Institute of Physiology, University of Veterinary Science, Budapest, Hungary.

            NAL Call Number: QP1 A17

Forced moulting has been induced in domestic hens by progesterone treatment (5 mg/day) for 25 days. Moult happened between the 11th and 19th day after the first treatment. Endocrine changes were followed during the moult by blood sampling in one week intervals. At the time of the last sampling, new egg laying cycle was initiated in all birds. Plasma progesterone concentration increased significantly in response to the treatment then tended to decrease. Oestrone and testosterone levels were the lowest during the period when feather loss was most intensive and increased in the course of feathering. This increase was significant in the case of oestrone. The level of 17-beta-oestradiol did not vary during moult induced by progesterone treatment. Plasma concentration of thyroxine significantly increased during feather loss, showing a maximum in the second and/or third week after the beginning of the treatment, while it decreased when feather growth had begun. Plasma triiodothyronine as well as corticosterone levels were the highest during the latest phase of moult, at the time of feather outgrowing. It has been supposed that moulting would be initiated in response to the synergistic effect on feather follicles of progesterone and thyroxine, which was stimulated by the progesterone treatment. The atrophic stage of the ovary suggested that progesterone was probably of adrenal origin. It was assumed that triiodothyronine and oestrone were responsible for controlling feather outgrowth.

Descriptors: Chickens--blood--BL, Corticosterone--blood--BL, Progesterone --pharmacology--PD, Sex Hormones--blood--BL, Thyroid Hormones--blood--BL , Chickens--growth and development--GD, Feathers--growth and development--GD


Tilbrook AJ; Johnson RJ; Eason PJ; Clarke I.J (1990). Induced pause in egg production using a synthetic hypothalamic peptide. Proceedings of the Australian Poultry Science Symposium p.105.

Animal Research Institute, Department of Agriculture and Rural Affairs, Werribee, Vic. 3030, Australia.

Moulting induced by nutrient restriction is accompanied by a decrease in circulating LH and reduced sensitivity of the pituitary gonadotrophs to GnRH. To study if treatment with a GnRH agonist would induce a pause in egg production, laying fowls were (1) injected subcutaneously with saline for 7 days (controls), (2) nutrient-restricted (by whole oat feeding), (3) injected with 100 micro g/kg of a GnRH agonist for 7 days, or (4) implanted with slow-release pellets containing 120 micro g of the agonist. Egg production and LH concentration were lower in the 2 GnRH agonist treatments than in the controls, but those for the nutrient-restricted group were lower than for the GnRH agonist-treated groups.

Descriptors: gonadotropins, GnRH, agonists, effects, moult, induction, LH, blood

            Copyright© 2002, CAB International


Tomita Y; Hayashi K; Honbo T (1977). Effects of citric acid on molting, egg production, activities of enzymes in liver and mineral levels in serum of natural molting hens. Bulletin of the Faculty of Agriculture Kagoshima University 27: 165-170.

NAL Call Number: 107.6 K114B


Verheyen G; Decuypere E; Chiasson RB; Vervloesem J; Kuhn ER; Michels H (1987). Effect of exogenous LH on plasma concentrations of progesterone and oestradiol in relation to the cessation of egg laying induced by different moulting methods. Journal of Reproduction and Fertility 81(1): 13-21.

NAL Call Number: 442.8 J8222

Artificially induced cessation of egg laying caused regression of the reproductive tract in hens, as well as changes in circulating concentrations of sex steroids. Hens were bled at several stages during and after artificial moult induced by fasting or overfeeding a diet low in calcium or high in zinc. Hens received a single injection of 200 i.u. of horse LH at Day 0, 7, 21, 35 and 77 (Exp. 1) or Day 0, 8, 23, 35 and 71 (Exp. 2) after start of the treatment to induce moult. Blood samples were taken before and 20, 40 and 60 min (Exp. 1) or 15, 30 and 45 min (Exp. 2) after LH injection. Hens which were fasted or given the diet high in zinc had low plasma progesterone concentrations and the response to LH was reduced or delayed. In hens fed low calcium the reduction in plasma progesterone was less pronounced and the responsiveness to LH was more or less maintained. Conversely, there was no response of oestradiol to LH in laying hens. However, oestradiol concentrations increased in moulting hens after LH injection, due to the high oestradiol secretion from the small white follicles, since all yolky follicles were atretic.

Descriptors: hens, egg formation, laying performance, molting hormones, progesterone, estradiol, luteinizing hormone


Verheyen G; Decuypere E; Kuhn ER; Herremans M (1986). Dissociation of the effect of thyroxine and triiodothyronine in relation to the halt, egg laying and moult in hens. Archiv fur Experimentelle Veterinarmedizin 40(2): 250-259.

Laboratory of Comparative Endocrinology, Zoological Institute, Naamsestraat 61, 3000 Leuven, Belgium.

            NAL Call Number: 41.8 EX7

Injection of 0.7 mg thyroxine (T4) or triiodothyronine (T3) during 3 consecutive days was studied in Warren SSL hens at 82 wk of age. In both treatment groups, half the hens were fed a commercial layer diet ad lib., and half were force-moulted by removing food for 8 days followed by food restriction (relative to ad lib. intake) for 20 days. Following T4 injections in ad lib.-fed hens, egg production remained relatively constant, but the effect on feather loss was rapid and pronounced. The T3 injections, however, decreased egg production in ad lib.-fed hens, but had only a small effect on moult.

Descriptors: egg production, thyroid hormones, moult, hens

            Copyright© 2002, CAB International


Zhvikas EB (1976). Effect of different methods of forced moulting on reproductive characters of laying hens. [Vliyanie razlichnykh metodov prinuditel'noi lin'ki na vosproizvoditel'nye kachestva yaichnykh kur.] Ptitsevodstvu 4: 110-118, 142-143.

Sbornik Rabot. Pribaltiiskaya Zonal'naya Opytnaya Stantsiya po

            NAL Call Number: Z5074 P8R4

Nine groups each of 75 Leghorn layers were treated as follows at the end of the 1st laying season: (1) controls, maintained under 14 h light daily and with access to food and water; (2) light stress (light period increased to 24 h daily for 10 days, shortened abruptly to 8 h daily for 1 mth, and then lengthened to 14 h daily) but with access to food and water; (3) light stress and with access to water but starved for 6 days; (4), (5), and (6) as in (3) but starved for 8, 10 or 12 days resp.; (7) light stress, with access to food and water, and fed 0.7 g thyroid extract daily; (8) as in (7) but injected with 50 mg progesterone; (9) darkness, and withdrawal of water and food for 3 and 4 days resp. For the 9 treatments resp., egg production to the onset of forced moulting at 68 wk of age averaged 247, 247, 244, 238, 246, 238, 250, 250 and 246 v 216, 191, 222, 247, 230, 228, 213, 192 and 226 in the following 52 wk, group 4 producing significantly more and group 2 significantly less than the controls. Production to 43 wk after the onset of forced moulting was significantly better in groups 3, 4, 5, 6 and 9 (201, 230, 217, 216 and 212) and worse in group 2 (156) than in controls (178). Egg fertility 3 and 11 mth after forced moulting was generally higher than in birds aged 15-16 mth, but hatchability of eggs set was lower (69.4-87.1 and 64.9-73.8 v 88.8-95.1%). Corresponding values for hatchability in the control group were 87.7 and 80.5% v 92.9.

Descriptors: moult, induction, laying performance

            Copyright© 2002, CAB International

Selected Websites

Research proposed and Funded by PEPA for 2001/2002: Use of an aromatase inhibitor to stimulate molt in laying hens. California Poultry Letter May /June 2001, Cooperative Extension - University of California at Davis


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October 23, 2002