Mineral Supplements and Deficiencies



Abu-Serewa S; Karunajeewa H (1985). A comparison of methods for rehabilitating aging hens. Australian Journal of Experimental Agriculture 25(2): 320-325.

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

            NAL Call Number: 23-AU792

Three of five groups of White Leghorn .times. Australorp hens aged 73 weeks, housed in cages, were fed a laying diet containing zinc (23.7 g/kg), or iodine (4.1 g/kg), or calcium (1.0 g/kg). The fourth group of hens was given only whole-grain barley while a fifth group given a normal laying diet served as the control. All groups were fed their respective diets until rate of lay dropped to 0% or less than 2%, and they were then given a normal laying diet until 97 weeks of age. Water was available at all times and 15.5 h of constant light was provided daily to all treatments throughout the experiment. Hens given the zinc and the whole-grain barley diets ceased egg production within 1 week and remained out of production for about 10 days. The hens in both of these treatments reached peak egg production (67%, on a hen day basis) 8 weeks after the initiation of treatments, after which they continued to lay at a higher rate than those given iodine, calcium and control treatments. Hens given the diets with either iodine or calcium reached their lowest rate of lay (1.6%) after 15 and 7 days of feeding the two diets respectively. They resumed laying immediately after the resumption of feeding the normal laying diet and reached peak egg production (59%) at 8 and 12 weeks after feeding the iodine and calcium diets respectively. The treated hens laid eggs with higher Haugh units and specific gravity values than those eggs of the controls. The lowest rate of decline in both those traits from the pretreatment values was in the zinc and barley treatments. These treatments also had the lowest percentage of cracked eggs. There was no significant difference among treatments in mean rate of lay, egg weight, or rate of mortality from 73 to 97 weeks of age. The present results suggest that feeding whole-grain barley can be used successfully to extend the productive life of laying hens beyond the first year of egg production if such an extension is desirable in a given economic situation. It is a simpler technique than the conventional method of induced moulting and the method of feeding a high level of zinc.

Descriptors: zinc, iodine, calcium, whole grain, barley, mean lay rate, egg production

            Copyright© 2002, Biosis


Albuquerque R de (1988). Effect of sodium chloride, zinc oxide and potassium iodide, compared with feed restriction, on induced molting in laying hens and their productivity. [Acao do cloreto de sodio, oxido de zinco e iodeto de potassio em comparacao com a restricao alimentar, sobre o descanso forcado em galinhas poedeiras e sua produtividade.] Thesis - Universidade de Sao Paulo Brazil, 86 pp.

NAL Call Number: SF494.A43

Departamento de Cricao de Ruminantes e Alimentacao Animal, Faculdade de Medicina Veterinaria e Zootecnia, Universidade de Sao Paulo, Sao Paulo, Brazil.

At 66 weeks old, 128 each of Babcock and Hisex Brown hens, caged singly, were deprived of feed for 11 days or given diets without added NaCl for 42 days or diets with 2% ZnO for 11 days or 0.6852% KI for 42 days. Thereafter all had the same commercial laying diet. Molting was induced by all treatments except NaCl deprivation. Subsequent productivity was significantly higher with feed deprivation and 2% ZnO than with the other treatments. With feed deprivation and 2% ZnO and body weight loss was higher, feed consumption lower and feed conversion better than the other treatments. Egg weight was highest and quality of eggs, measured by Haugh units, and quality of shells was poorest in group 1. Survival rate was not affected by treatment. Results between strains are compared.

Descriptors: molting, restricted feeding, sodium chloride, zinc oxide, potassium iodide , egg quality


Alsobayel AA; Alkhateeb NA (1992). Effect of force molting induced conventionally or by high dietary aluminum on egg and shell quality of laying hens. Asian-Australasian Journal of Animal Sciences 5(2): 341-347.

King Saud University, Riyadh, Saudi Arabia

NAL Call Number: SF55.A78A7

Descriptors: hens, molting, aluminum, egg quality


Alsobayel AA; Alkhateev NA (1992). Evaluation of high dietary aluminum as a force-resting agent in laying hens. Arab Gulf Journal of Scientific Research 10(3): 81-92.

Department of Animal Production, College of Agriculture, King Saud University, PO Box 2460, Riyadh 11451, Saudi Arabia.

            NAL Call Number: Q1 A65

Laying Saudi Arabian Baladi hens were subjected to 4 dietary treatments: fed to appetite on a commercial control layer diet containing 17% crude protein, 3.6% calcium and 0.343% available phosphorus; fed initially on a commercial force-molting diet, starved for 10 days and then fed for 18 days on cracked maize; and fed for 15 days to appetite on the control diet supplemented at 0.35% with aluminum as Al sulphate or Al chloride. During the molting period hen-day egg production was 45.02, 37.50, 38.32 and 40.66 eggs, respectively. The added Al depressed feed intake and body weight. Concentration of inorganic P in plasma was highest with the control diet and lowest with aluminum chloride; differences between groups were not significant 10 days after the end of dietary treatments.

Descriptors: hen feeding, aluminum, mineral supplements, molting, egg production, poultry, minerals, trace elements, calcium, phosphorus

            Copyright© 2002, CAB International


Berry WD; Brake J (1987). Postmolt performance of laying hens molted by high dietary zinc, low dietary sodium, and fasting: egg production and eggshell quality. Poultry Science 66(2): 218-226.

NAL Call Number: 47.8 AM33P

Descriptors: hens, reproductive performance, molt, fasting, zinc, sodium, photoperiod, egg production, egg shell quality


Berry WD; Brake J (1985). Comparison of parameters associated with molt induced by fasting, zinc, and low dietary sodium in caged layers. Poultry Science 64(11): 2027-2036.

NAL Call Number: 47.8 AM33P

Descriptors: hens, molt, fasting, zinc, sodium, physiological functions, cage rearing


Berry WD; Gildersleeve RP; Brake J (1987). Characterization of different hematological responses during molts induced by zinc or fasting. Poultry Science 66(11): 1841-1845.

Department of Poultry Science, North Carolina State University, Raleigh, NC 27695-7608.

            NAL Call Number: 47.8 AM33P

Single Comb White Leghorn hens were induced to molt by complete fasting for 11 days (FAST) or feeding a layer ration that contained 20,000 ppm zinc as zinc oxide for 11 days (ZINC). In both cases hens lost approximately 30% of their initial body weight. A control (CON) group was maintained. At 4, 8, 12, 18, and 42 days after initiation of the treatments, total erythrocyte numbers (TRBC), percent packed cell volume (PCV), mean corpuscular volume, hemoglobin (Hb), mean corpuscular hemoglobin (MCHb), and mean corpuscular hemoglobin concentration (MCHC) were determined. Erythrocytes were characterized as reticulocytes, intermediate Stage VII erythrocytes, or mature Stage VIII erythrocytes. The FAST hens exhibited significantly increased PCV through 18 days, which was not exhibited by ZINC hens. The FAST treatment increased TRBC on Days 8 and 12 and decreased TRBC on Day 42 while ZINC decreased TRBC on Day 4 and increased TRBC on Day 12. The FAST hens exhibited decreased Hb on Day 42, as reproduction resumed. Both ZINC and FAST hens exhibited decreased MCHb and MCHC on Day 12. Percentages of reticulocytes were decreased at Day 4 by FAST and increased at Days 8 and 18 by ZINC. Stage VII erythrocytes were decreased on Days 4 and 12 in FAST hens whereas ZINC hens exhibited a decrease on Day 4 and an increase on Days 8 and 18. Concomitantly, FAST hens exhibited an increase in Stage VIII erythrocytes on Days 4 and 12, whereas an increase on Day 4 and decreases on Days 8 and 18 were observed in ZINC hens.

Descriptors: Chickens--blood--BL, Fasting, Feathers--physiology--PH, Zinc --pharmacology--PD, Zinc Oxide--pharmacology--PD , Chickens--physiology--PH, Erythrocyte Count--veterinary--VE, Erythrocyte Indices--veterinary--VE, Feathers--drug effects--DE, Hematocrit--veterinary --VE, Hemoglobins--analysis--AN


Bessei W (1978). Use of a low-sodium diet to induce a laying pause in hens. [Die Anwendung einer natriumarmen Ration zur Steuerung der Legepause bei Legehennen.] Archiv fur Geflugelkunde 42(3): 115-122.

Lehrstuhl fur Kleintierzucht, Univ. Hohenheim, Postfach 106, 7000 Stuttgart 70, German Federal Republic

            NAL Call Number: 47.8 AR2

After 12 months of egg production 1600 hens in 2 groups were fed on a low-Na diet for 3 or 4 weeks. Subsequent production and egg quality were recorded for 8 periods of 4 weeks. Within 3 weeks egg production decreased to below 3%. Both groups reached 50% hen-day production at the 11th week and rose to a peak of 82 to 83%. When the low-Na diet was introduced, egg weight decreased and then increased to 67 g when the hens were transferred to the normal diet. Egg shell strength was improved until the 16th week of trial and then decreased. Egg shell deformation, percentage egg shell and albumen index also improved in the first part of the second year. Yolk colour decreased after the treatment and reached normal values after 20 weeks. During feeding on the low-Na diet mortality increased but returned to normal after changing to the complete diet. There was no significant difference between groups for egg production, egg weight, albumen index or yolk colour. The egg shell quality was better and the mortality higher in the group on the low-Na diet for 4 weeks.

Descriptors: egg production, feeds, sodium, molt, induction, laying performance, nutrition

            Copyright© 2002, CAB International


Bessei W; Lantzsch HJ (1980). Induction of pauses in laying with diets rich in zinc. [Untersuchungen zur Einleitung von Legepausen mit zinkreichen Rationen.]. Archiv fur Geflugelkunde 44(3): 133-140.

Lehrstuhl Kleintierzucht, Garbenstr. 17, 7000 Stuttgart 70 - Hohenheim, German Federal Republic.

            NAL Call Number: 47.8 AR2

To investigate the effect of zinc concentration in the diet of laying hens on egg production and egg Zn levels, groups of 8 White Leghorn Hybrid (LSL) laying hens were given diets with Zn 5000, 10 000, 15 000 or 20 000 mg/kg feed for periods of 2, 4, 6 or 8 days, following which normal laying diets were given. Each of the 16 treatment combinations was replicated 8 times, and the trials were conducted for 4 laying periods of 4 weeks. Egg production during administration of the Zn-rich diets decreased with increasing Zn concentration and duration of treatment. Treatments producing the most marked reduction in output were those which gave the best output during the third and fourth laying periods. During these periods there were no treatment-related differences in the consumption of the standard diet. The daily intake of Zn decreased in the groups given the highest level of dietary Zn for the longest period, and efficiency of feed conversion was increased in the groups given Zn-rich diets for periods greater than 2 days. Zn in eggs showed a slight increase with duration of treatment but no apparent effect due to Zn concentration and even the highest level recorded (54 mg/kg) would be harmless to humans. Body Zn levels were estimated in other birds fed similarly. Concentration of Zn or duration of treatment had no significant effect on levels of Zn.

Descriptors: zinc, hen feeding, hens, egg production

            Copyright© 2002, CAB International


Brake J (1993). Recent advances in induced molting. Poultry Science 72(5): 929-931.

North Carolina State University, Raleigh, NC

NAL Call Number: 47.8 AM33P

Molt induction methods that produce a complete cessation of lay, reproductive involution for several days, and loss of nearly 50% of the primary feathers are the most successful. Feed deprivation and high levels of dietary zinc have proven to be the most consistent methods available. Calcium appears to play a pivotal role in molt induction as calcium carbonate feeding prolongs ovulation during the initial stages of an induced molt and dietary zinc has been shown to interfere with calcium-related metabolic activities at the level of the ovary. The primary site of action of feed deprivation appears to be at the level of the hypothalamic-hypophyseal axis, where calcium is involved in many endocrine pathways. The physiological basis of postmolt rejuvenation has been related to the extent of ovarian and oviductal involution. Evidence suggests that restructuring of receptor or membrane functions in the oviduct is the basis for rejuvenation. A body weight loss of about 30% appears to be necessary for appropriate restructuring of the shell gland.

Descriptors: hens, molting, induction, zinc, calcium, weight losses, fasting, feathers, lh, ovaries, suppression, c-amp, oviducts, epithelium


Breeding SW; Brake J; Garlich JD; Johnson AL (1992). Molt induced by dietary zinc in a low-calcium diet. Poultry Science 71(1): 168-180.

North Carolina State University, Raleigh, NC

NAL Call Number: 47.8 AM33P

Three experiments were designed to test the hypothesis that zinc has a specific effect independent of anorexia during induction of molt. In Experiment 1, hens were fed a low-calcium (.08%) basal molt diet to which was added 0, 110, 620, or 1,120 mg/kg (ppm) zinc as zinc sulfate heptahydrate (ZnSO4.7H2O) for 7 days and 0, 1,400, 2,800, or 4,200 ppm zinc, respectively, for the following 14 days. In Experiment 2, hens were provided ad libitum access to the low-calcium basal molt diet with 2,800 ppm added zinc for 14 days during which a paired control hen received a similar amount of the low-calcium basal molt diet. In Experiment 3, hens were fed the low-calcium basal molt diet on a restricted basis amended with either 0 or 2,800 ppm zinc on a restricted basis for 10 days. In Experiment 1, all hens that consumed zinc had significantly fewer days to last oviposition as compared with control hens, and this occurred without significant differences in body weight or feed consumption for the lowest zinc group. When compared with the control group, higher levels of zinc did decrease body weight and feed consumption. In Experiment 2, the hens consuming the diet with 2,800 ppm zinc (Zn2800) reached last oviposition significantly sooner than control hens, although the Zn2800 hens actually consumed more feed. In Experiment 3, the Zn2800 hens lost more body weight than control hens due partially to earlier reproductive tract regression. Serum luteinizing hormone was increased in the Zn2800 hens. In the absence of supplemental dietary calcium, dietary zinc in moderate concentrations (less than or equal to 52,800 ppm) has a specific suppressing effect on reproduction independent of anorexia.

Descriptors: hens, zinc, feed intake, molt, follicles, calcium, mineral deficiencies, body weight, egg production, ovaries, weight, oviducts


Breeding SW; Berry WD; Brake J (1992). Research note: maintenance of duodenum weight during a molt induced by dietary zinc in a low-calcium diet. Poultry Science 71(8): 1408-1411.

North Carolina State University, Raleigh, NC

NAL Call Number: 47.8 AM33P

The duodenal loop was excised from hens that had been induced to molt by a low-calcium diet containing 2,800 ppm zinc in the form of zinc sulfate heptahydrate. This was compared to that of hens pair-fed a layer diet. In Experiment 1, hens exhibited an increased duodenum weight after receiving the zinc diet for 14 days but no differences remained 14 days later. In Experiment 2, increased duodenum weight was noted after 4 days on the zinc diet and this persisted through 10 days. This greater tissue weight was observed whether expressed on a wet or dry weight basis. Thus, there was a persistency of tissue mass. The duodenum does not regress during a zinc-induced molt as it does during a fast-induced molt.

Descriptors: hens, dietary minerals, mineral deficiencies, calcium, zinc, molt, duodenum, weight, induced molt


Cunningham DL; McCormick CC (1985). A multicycle comparison of dietary zinc and feed removal molting procedures: production and income performance. Poultry Science 64(2): 253-260.

Dep. Of Poultry And Avian Sciences, Cornell University, Ithaca, NY 14853.

            NAL Call Number: 47.8 AM33P

Two experiments were conducted to evaluate performance and income factors associated with ZnO and feed removal multicycle molt programs. Experiment 1 compared 2 strains of commercial White Leghorn layers molted with 20,000 ppm ZnO in the feed for 4 days with a feed removal program of 10 days followed by 10 days of cracked corn. Experiment 2 compared a single strain of White Leghorn layers molted with 20,000 ppm ZnO with feed removal for 4 and 10 days. Body weight loss during molt averaged 25-30% for the longer duration molt programs compared to 14-16% for the short duration programs. Differences on body weight loss between ZnO and feed removal programs employing the same durations of treatment were not significant (P < 0.05). No significant (P < 0.05) differences were observed between ZnO and feed removal programs for hen-housed egg production, days to reduce egg production to 0%, feed usage or mortality rates. Differences in egg size and egg grade distributions were observed among molting programs and strains. Incomes over pullet and feed costs for the molted flocks were greatest during the 1st molt cycle. Incomes over pullet and feed cost during the 2nd molt cycle were generally negative. The longer duration molt programs resulted in total incomes over feed and pullet costs averaging 5.0.cents./doz more than the shorter 4 day duration programs. Duration of molt-inducing periods had greater effects on performance and income results than did the method used to induce rest.

Descriptors: white leghorn chicken, corn, metabolic-drug, egg production, pharmacodynamics


Dalin VN (1977). Development of a method for moult induction in intensively reared hens. [Razrabotka metodiki provedeniya prinuditel'noi linki kur v usloviyakh ikh itensivnogo soderzhaniya.] Izvestiya Timiryazevskoi Sel'skokhozyaistvennoi Akademii (No. 6): 158-169, 228.

The method developed involves (1) the withdrawal of food for 4 days, and its reintroduction in a manner depending on the initial stage of moulting, (2) the use of low-calcium diet, and (3) 2 periods (4 days and 3 days resp.) of complete darkness. For 3 groups, each of 8900 layers, induced to moult using this method, induced to moult by the previously used Canadian method, and not induced to moult, egg production per hen in 9 mth averaged 108.0, 126.0 and 106.4 resp.

Descriptors: moult, induction, methodology, egg production

            Copyright© 2002, CAB International


Daniel M; Balnave DA (1980). A comparison of methods of inducing a pause in egg production in crossbred layers. Australian Journal of Agricultural Research 31(6): 1153-1161.

Dep. Animal Husbandry, Univ. Sydney, Werombi Road, Camden, NSW 2570, Australia

            NAL Call Number: 23 Au783

In experiment 1, 20 replicates of 6 White Leghorn X Australorp laying hens, aged 84 weeks, were allocated to each of 4 treatments. The first involved withholding water and feed for 2 and 7 days, respectively; thereafter 50 g cracked wheat daily was given to each bird for 2 weeks followed by free access to a commercial laying diet. The second group was offered a diet containing zinc 18.7 g/kg for 7 days and were then treated as group 1. The third group was given a diet containing calcium 0.9 g/kg for 4 weeks and then returned to the commercial laying hen diet. The fourth group was allowed free access to cracked wheat for 2 weeks then 50 g wheat/bird daily for 2 weeks followed by the commercial diet. Birds on treatments 2 to 4 consumed 12, 114.1 and 98 g daily, respectively, during the first 7 days compared to 136.2 g for all birds at the start of the trial. After returning to the commercial diet, birds fed on treatments 1 to 4 ate 129.1, 130.1, 121.1 and 127.1 g daily, respectively, between 89 and 104 weeks. Mean bodyweights at 104 weeks were 2.081, 2.041, 2.126 and 2.008 kg compared to a mean weight of 2.110 kg at 84 weeks. Egg production for these birds was 65.55, 63.34, 48.07 and 55.24 eggs/100 birds. In experiment 2 each of 4 commercial laying diets was given to 3 replicates of 4 White Leghorn X Australorp hens, aged 84 weeks. The diets were supplemented with Zn 2.2, 4.1, 7.5 and 18.7 g/kg as zinc oxide. After 1 week, birds on diets 3 and 4 were given 50 g cracked wheat daily for 2 weeks before being allowed free access to the unsupplemented layer's diet. Birds on diets 1 and 2 continued on these diets for 3 weeks when they were returned to the unsupplemented layer's diet. Birds on diet 4 ceased lay by day 7 and those on diet 3 by day 8. Birds on diets 1 and 2 had their rates of lay reduced to 44% and 22%, respectively by the end of week 3, compared to a rate of lay of 50% at the start of the trial. There was no significant difference among treatments in mean food intake, daily egg production, mean egg weight or Haugh unit value following the return to the commercial diet.

Descriptors: egg production, molting, molt, induction, methodology

            Copyright© 2002, CAB International


Douglas CR; Harms RH; Wilson HR (1972). The use of extremely low dietary calcium to alter the production pattern of laying hens. Poultry Science 51(6): 2015-2020.

Dep. Poultry Science, Florida Agricultural Experiment Station, Gainesville, Fla. 32601.

            NAL Call Number: 47.8 AM33P

Hens that had been laying for 6 months were individually caged and given for 16 weeks diets based on maize and soya bean meal. The control mixture contained 3% Ca and 0.7% P, other groups were given 0.09% Ca and 0.32% P for 14 or 42 days and after that the control diet. Many hens given the low-Ca diet were unable to stand after 3 days but soon recovered. By 14 days egg production had fallen from 65 to 12%. Four weeks later, after returning to the control diet, egg production was similar to that of control birds. Egg production of the 42 days depleted group fell to 2% by 4 weeks. After return to the control diet, it increased only to about 40%. The sp. gr. of eggs was not affected by any treatment. Mortality was 8.6% for controls, 28.6% for the low-Ca groups.Hens in production for 10 months were given for 20 weeks the same diets as before and a further group was given the low-Ca diet for the whole period. After 2 weeks egg production of all low-Ca groups had fallen to about 3%. After return to the control diet both groups exceeded control group egg production 10%. Birds continuously given the low-Ca diet had a mean egg production of about 6%. Egg shell thickness was significantly greater at 60 days in groups depleted for 42 days in controls. Bodyweight of birds continuously given the low-Ca diet was significantly lower than that of all other groups; the breaking strength of the tibia and bone ash were significantly lower. The possibility is considered that suspension of laying induced by a short period on low-Ca diet might replace forced molting.

Descriptors: poultry, feeding, calcium, intake, egg production, hens


Filipovic Z; Stevancevic M (1999). Application of ZnO in diet for induction of molting in SSL-hybrid hens on a farm "Koka-Promet" in Budva, Yugoslavia. [Primjena ZnO u ishrani za izazivanje prinudnog mitarenja kod kokica SSL-hibrida na farmi "Koka-promet" u Budvi.] Zivinarstvo 34(10): 9-12.

Javna veterinarska ustanova Republike Crne Gore, Podgorica, Yugoslavia.

The use of zinc oxide (ZnO) for induction of molting was evaluated on a farm of 10 000 of SSL-hybrid hens in Budva, Yugoslavia, in April 1997. ZnO was added to the diet at 15 kg/600 kg of diet at the end of technological laying period at 73 weeks of age. molting was completed within 8 to 10 days and new feathers appear 28 days after molting. Laying period was extended by 10 months after induction of molting, at which time egg production was 53%. It is concluded that ZnO at 25 000 ppm/1000 kg of feed has no toxic effect. Total mortality during 10 months of extended laying period was 7%.

Descriptors: molting, poultry, zinc oxide, diets, mortality, egg production, hens


Franchini A; Meluzzi A; Urrai G; Bertuzzi S; Giordani G (1986). Induction of moulting in laying hens. 2. Effect of starvation and diets deficient in calcium and sodium. [Induzione della muta nelle galline ovaiole. 2. Effetti del digiuno e di diete calcio e sodio carenti.] Avicoltura 55(3): 14-17.

Istituto Zoocolture, Facolta di Agraria, Univ. degli Studi, Bologna, Italy

            NAL Call Number: 47.8 R523

Moulting was induced in 216 Warren laying hens, 74 weeks old, by starvation, a diet with 0.04% calcium or a diet with 0.02% sodium. Egg laying ceased after 8 days of starvation and decreased to 5 and 6% of normal after 15 and 28 days on the diets deficient in Ca or Na. Weight loss was 15.89, 12.29 and 10.71 g, respectively. Resumption of laying after feeding to appetite took longer but performance during the 2nd production cycle was best in starved hens. Egg weight and shell density were unaffected by molting method. Albumen quality was improved by starvation.

Descriptors: moult, starvation, hens, calcium, deficiency, sodium

            Copyright© 2002, CAB International


Francis DW; Roberson RH (1980). Chemical constituents of blood from chickens subjected to molt. Poultry Science 59 (7): 1610.

Dep. Animal and Range Sciences, New Mexico State Univ., Las Cruces, NM 88003, USA.

            NAL Call Number: 47.8 AM33P

Laying hens, 3/cage, were bled before moult, after moult induced by deprivation of feed or giving zinc, and 3 times after return to lay. Inorganic phosphorus, potassium and albumin were significantly different between controls and treated hens. Means for lactic dehydrogenase and serum glutamic oxaloacetic transaminase were greater in the treated groups than in controls. Thirteen blood constituents were significantly different for the treatment X period interaction. The largest difference, which occurred between the control and the 2 treated groups after moulting, was associated with weight loss and cessation of egg production.

Descriptors: blood composition, moulting

            Copyright© 2002, CAB International


Gascon FM; Piquer JG; Vinas L (1985). Comparative study of two methods of forced moult in layers. II. [Estudio comparativo de dos metodos de muda forzada en ponedoras. II.] Medicina Veterinaria 2(9): 413-421.

Dep. Path., Fac. Vet., Zargoza, Spain.

Comparison of serum corticosterone, heterophil percentage and relative adrenal weight in two groups of each of 60 layers undergoing the feed and water restriction method or the zinc oxide method of forced moult revealed significant increases in all these values with the first method, but not with the zinc oxide method.

Descriptors: hens, restricted feeding, zinc, moulting, stress, moult

            Copyright© 2002, CAB International


Gascon FM; Piquer JG (1985). Comparative study in two methods of forced molting in laying hens, 3: Effect on different protein fractions and total serum proteins. [Estudio comparativo de dos metodos de muda forzada en ponedoras, 3: Efecto sobre las diferentes fracciones proteicas y proteinas totales sericas]. Medicina Veterinaria 2(10): 487-492.

Zaragoza Univ., Spain, Facultad de Veterinaria

The serum protein fractions and total protein in 180 White Leghorn hens of 44 weeks of lay are studied during a forced molt using two different methods: feed and water restriction and zinc oxide. The hiprotaenemia is very significant (P<0.01) in both molting groups but there are no differences between them, except the decrease of gamma-globulins what is higher in the feed and water restriction group. In the other serum proteic fractions no differences have been observed between the three groups. According to the results observed the zinc oxide method seems better than the feed and water restriction for the practice of forced molt.

Descriptors: layer chickens, molting, globulins, albumins, blood protein disorders, water deprivation, oxides, zinc, animals, biological rhythms, birds, blood composition, blood disorders, blood proteins, chickens, composition, disorders, domestic animals, domesticated birds, elements, galliformes, heavy metals, industrial pollutants, injurious factors, inorganic compounds , metals, nutrition, nutritional phenomena, organic compounds, pollutants, poultry, proteins, time, timing, vertebrates


Goodman BL; Norton RA; Diambra OH (1986). Zinc oxide to induce molt in layers.

Poultry Science 65(11): 2008-2014.

NAL Call Number: 47.8 AM33P

The effects of the addition of Zn as ZnO to diets to induce molt were evaluated against a fasted control. Experiment 1 involved 315 Leghorn hens, 15 months old, randomly distributed among five treatments, each replicated seven times with 9 hens per replicate. Hens fasted for 10 days were compared with hens fed diets to which ZnO was added at 10,000, 5,000, or 2,500 ppm for 7, 14, or 21 days. No significant differences were observed among treatments for days to return to 50% production, hen-day and hen-housed production, egg weight, grams egg per hen-day, grams of feed per gram egg, mortality, or Haugh units during the 22-week experimental period. Experiment 2 involved 420 Leghorn hens, 18 months old, randomly distributed among five treatments, each replicated seven times with 12 hens per replicate. Treatments involved fasting for 10 days or feeding diets with 10,000, 5,000, or 2,500 ppm ZnO fed for 7, 14, or 21 days. Hens fasted and hens fed diets with 10,000 ppm ZnO at the start of the experiment ceased production in significantly less time (4.6 to 6 days) than hens fed 5,000 ppm ZnO (14.3 to 14.9 days); however, days to return to 50% production from the start of the experiment did not differ among treatments. Feed consumption and feed cost per hen day during molt were lowest (P less than .05) in the fasted hens.

Descriptors: physiology--PH; Feathers--drug effects--DE; Zinc--pharmacology --PD; Zinc Oxide--pharmacology--PD ; Diet CAS Registry No.: 1314-13-2 (Zinc Oxide); 7440-66-6 (Zinc)


Harms RH (1991). Effect of removing salt, sodium, or chloride from the diet of commercial layers. Poultry Science 70(2): 333-336.

University of Florida, Gainesville, FL

NAL Call Number: 47.8 AM33P

Two experiments were conducted with Hy-Line W-36 hens. The hens were 45 and 65 wk old at the start of Experiment 1 and 2, respectively. A corn-soybean meal basal diet was used. Four diets were fed for 19 days: 1) control; 2) no added NaCl; 3) no added NaCl with Na supplied as NaHCO3; and 4) no added Na with Cl supplied as CaCl2. All hens were fed the control diet from Day 20 to Day 84. Hens fed a diet without NaCl reached zero production in 9.8 and 13.3 days in Experiments 1 and 2, respectively. Hens fed the diet without Na reached zero production in 10.3 and 13.1 days in Experiments 1 and 2, respectively. Only a few of the hens fed the diets with no Cl reached zero production. Time required for all hens to return to production after returning to control diets were 16.0, 15.7, and 6.0 days for hens receiving no added NaCl, Na, or Cl, respectively in Experiment 1, and 13.2, 15.0, and .6 days in Experiment 2. Molting occurred in 92.7, 77.8, and 24.2% of the hens receiving the no NaCl, Na or Cl, respectively, in Experiment 1, and 80.0, 72.5, 30% in Experiment 2. Mortality rates were 7.5, 12.5, 20.0, and 5.0% for the hens receiving diets with no NaCl, Na, Cl or control, respectively, in Experiment 1, and 2.5, 10.0, 20.0, and 0% in Experiment 2.

Descriptors: hens, sodium chloride, egg production, molt, feed intake, feathers, mortality, mineral deficiencies, egg weight, specific gravity ;


Harms RH (1983). Benefits of low sodium in the diets of laying hens during the period prior to forced rest. Poultry Science 62(6): 1107-1109.

NAL Call Number: 47.8 AM33P


Hassan MSH (1996). Physiological changes in laying fowl during forced molting. Thesis Degree: Thesis (M.Sc. in Poultry Production) Cairo Univ. (Egypt). Faculty of Agriculture, 156 p.

Availability: Library, of Faculty of Agriculture, Cairo Univ., Egypt

Descriptors in English: layer chickens, forced molting, zinc, feed additives, laying performance, animal performance, blood composition, additives, animal husbandry methods, animal performance, birds, blood, chickens, domestic animals, domesticated birds, elements, galliformes, heavy metals, livestock, metallic elements, poultry


Hussein AS; Cantor AH; Johnson TH (1989). Comparison of the use of dietary aluminum with the use of feed restriction for force-molting laying hens. Poultry Science 68(7): 891-896.

University of Kentucky, Lexington, KY

NAL Call Number: 47.8 AM33P

Descriptors: hens, molting, aluminum sulfate, restricted feeding, egg production


Johnson AL; Brake J (1992). Zinc-induced molt: evidence for a direct inhibitory effect of granulosa cell steroidogenesis. Poultry Science 71(1): 161-167.

Department of Animal Sciences, Rutgers, State University of New Jersey, New Brunswick, New Jersey 08903, USA.

            NAL Call Number: 47.8 AM33P

Results from previous studies indicate that the use of dietary zinc may provide an effective means to initiate an induced molt in laying hens. Although much evidence indicates that high concentrations of zinc (10 000 to 20 000 ppm) cause the cessation of lay primarily by reducing feed intake, recent data suggest that lower concentrations (2800 ppm) in a calcium-deficient diet may have a direct action on the ovary. Therefore, in a series of in vitro studies it was evaluated whether zinc can affect granulosa cell progesterone production. Incubation of granulosa cells from the largest preovulatory (F1) follicle with Zn as zinc sulfate (0.1 to 10 micro M) had no effect on basal progesterone production. By contrast, ovine LH-stimulated progesterone production was inhibited (P<0.05) in a dose-related fashion by Zn in both the sulfate and acetate forms (1 to 10 micro M). Furthermore, Zn attenuated ovine LH- and forskolin-induced cyclic adenosine monophosphate (cAMP) formation, and inhibited 8-bromo-cAMP- and calcium ionophore (A23187)-induced progesterone production. Such results indicate both pre- and post-cAMP sites of action for the inhibitory actions of Zn on progesterone production in F1 granulosa cells. Finally, ovine FSH-stimulated cAMP accumulation and progesterone production in granulosa cells collected from 9- to 12-mm follicles (a stage of development representing the early, rapid growth phase) were suppressed (P<0.05) by co-incubation of cells with Zn. From these data, it can be concluded that the effectiveness of Zn to induce the cessation of lay is due, at least in part, to a direct inhibitory action on ovarian granulosa cell function both in differentiating and in preovulatory follicles.

Descriptors: steroid metabolism, granulosa cells, zinc, intake, hens, molting, molt, induction, nutrition, ovaries, steroidogenesis, in vitro, minerals


Kilic A; Kor I (1983). Effects of induction of moulting by zinc oxide in laying hens. [Yumurta tavukculugunda cinko oksit ile tuy dokumune zorlanimin etkinlikleri uzerine arastirmalar.] Ege Universitesi Ziraat Fakultesi Dergisi 20(3): 15-28.

For 4 days groups of 6500 Golden Comet laying hens 76 weeks old were given a layer feed alone or with zinc oxide 25 g/kg. Zn increased egg yield and profitability but decreased feed intake and liveweight which however improved with time. Induction of moulting by Zn supplement was considered better than conventional methods.

Descriptors: hen feeding, zinc, supplements, egg production, moult

            Copyright© 2002, CAB International


Kuchinski KK; Harms RH (1994). Signs observed in commercial laying hens fed a low dietary salt level. The Journal of Applied Poultry Research. 3(1): 93-99.

University of Florida, Gainesville, FL.

NAL Call Number: SF481.J68

Descriptors: hens, dietary minerals, sodium chloride, mineral deficiencies, laying performance, molting, follicles, feed intake, egg weight, specific gravity, sodium-restricted diets, duration


Lukarev T; Dodovski M; Prodanov R (1988). The use of zinc oxide in feed for the induction of moult in light egg-laying hybrids. [Primena cink oksida u ishrani za izazivanje prinudnog mitarenja kod lakih hibrida.] Peradarstvo 23(5-6): 139-145.

Veterinary Institute, Skopje, Yugoslavia

            NAL Call Number: SF481 P4

Moult was induced in Hisex hens aged 79, 80, 83 or 85 wk (3265, 8000, 804 and 480 females per group resp.) using supplementation of feed with zinc oxide (2.5 kg/100 kg feed) and shortening daylight to 12 h daily. Egg production decreased to 50% within 2 days of the beginning of treatment, and to 0 on the 7th day; the pattern was similar for all age groups. Feed consumption, and consequently body weight, also decreased: on the 7th day of treatment, feed consumption was only 20% of that before treatment, and body weight decreased from 1920-2030 to 1704-1807 g during that period. moult began on the 10th-12th day. Feed intake increased to normal within a week from the end of treatment, and egg production resumed during the 2nd week.

Descriptors: moult, induction, nutrition, zinc oxide, zinc, hens, poultry

            Copyright© 2002, CAB International


Marafi A; Goodman BL; Gholson JT (1981). Recycling methods in adult hens (Forced molt, byfeed and water removal, nicabozin, low calcium, protein, sodium). Ag Review Southern Illinois University, School of Agriculture p. ANI5-ANI7.

NAL Call Number: S537.S5S6


Mather FB; Wilson HR; Ingram DR (1982). Performance and oviductal histology of hens as influenced by low calcium and-or low sodium diets during a force molt. Poultry Science 61(7): 1385-1386.

            NAL Call Number: 47.8 AM33P

Descriptors: hen, premature, egg production, magnum, atrophy, isthmus


McCormick CC; Cunningham DL (1987). Performance and physiological profiles of high dietary zinc and fasting as methods of inducing a forced rest: a direct comparison. Poultry Science 66(6): 1007-1013.

NAL Call Number: 47.8 AM33P

Descriptors: hen feeding, fasting, zinc, body weight, egg production, ovaries (animal), oviducts, rest


McCormick CC; Cunningham DL (1984). Forced resting by high dietary zinc: tissue zinc accumulation and reproductive organ weight changes (Laying hens). Poultry Science 63(6): 1207-1212.

NAL Call Number: 47.8 AM33P

An experiment was conducted to investigate the effects of high dietary zinc, as a means of inducing a forced-rest, on selected organ accumulation of zinc and reproductive function in terms of ovary and oviduct weight in the laying hen. Single Comb White Leghorn hens laying approximately at 60% production were fed either 10,000 ppm zinc as zinc oxide (10 Zn) or 20,000 ppm zinc (20 Zn) for a period of 4 days. At the initiation of the experiment (Day 0), five hens were killed and organs obtained for analysis. On 4, 10, 16, and 22 days afterward, similar samples were obtained from 5 hens per treatment. Ovary and oviduct weights were determined and zinc analysis performed on the latter as well as liver, kidney, and pancreas. The brief 4-day feeding of either high zinc diet caused a marked 80% reduction in ovary weight by Day 10. The oviduct, although less affected, was still reduced approximately 60% in weight after feeding either 10 Zn or 20 Zn for 4 days. The oviduct exhibited a statistically significant elevation in zinc concentration on Day 4 but was normal by Day 10 (6 days following the refeeding of a normal diet) and not different between treatments. There was extensive accumulation of zinc in kidney, liver, and especially pancreas after 4 days of feeding either 10 Zn or 20 Zn. The level of dietary zinc had no effect on the extent of accumulation in any tissue. The depletion of tissue zinc roughly corresponded to the magnitude of increase in the concentration of zinc observed at Day 4. Possible ramifications of the dramatic increase observed in pancreatic zinc were discussed. We concluded that feeding either 10 Zn or 20 Zn as a means of inducing a forced rest effects a marked and rapid reduction in ovary and oviduct weight as well as an extensive increase in renal, hepatic, and especially pancreatic zinc.

Descriptors: *Chickens--metabolism--ME; *Ovary--anatomy and histology--AH; *Oviducts --anatomy and histology--AH; *Zinc--administration and dosage--AD; *Zinc --metabolism--ME; *Zinc Oxide--administration and dosage--AD ; Chickens--anatomy and histology--AH; Diet; Kidney--metabolism--ME; Liver --metabolism--ME; Organ Specificity; Organ Weight; Pancreas--metabolism--ME


McCormick CC; Cunningham DL (1984). High dietary zinc and fasting as methods of forced resting: a performance comparison (Hens). Poultry Science 63(6): 1201-1206.

NAL: 47.8 AM33P


McCormick CC; Cunningham DL (1982). Forced molting of laying hens by zinc toxicity.

Proceedings - Cornell Nutrition Conference for Feed Manufacturers, p. 17-24.

NAL Call Number: 389.79 C81

A study was conducted to compare fasting and high dietary zinc as procedures to induce a forced rest of laying hens. Five to six replicates (25 hens each) of Single Comb White Leghorn hens laying approximately 60% were fasted for 10 days (fasted) or fed either 10,000 ppm zinc (10 Zn) or 20,000 ppm zinc (20 Zn) for a period of 4 days. A fourth treatment consisted of feeding 20,000 ppm zinc for 8 days (20 Zn-8). During the rest-inducing period, hens consumed little of either high zinc diet. Four-day intake by 20 Zn hens averaged 17.6 +/- .2 g/hen/day compared to 32.6 +/- 1.5 g/hen/day (means +/- SEM) for 10 Zn hens. Those fed 20 Zn-8 consumed the least amount, 12.6 +/- .2 g/hen/day during the 8 days of high zinc feeding. Body weight loss of hens in this last group was comparable to hens fasted for 10 days (fasted), i.e., 24.6 +/- .3% vs. 27.6 +/- .4%. Weight loss of hens in the remaining two groups reflected, to some extent, differences in feed consumption. The 20 Zn hens lost significantly more body weight during the 4-day period when compared with 10 Zn hens (16.2 +/- .4% vs. 11.9 +/- .5%). Each treatment resulted in a sharp drop in egg production. By the 5th day, fasted, 20 Zn, and 20 Zn-8 hens had ceased producing eggs. Egg production by 10 Zn hens declined at a slightly slower rate. There were considerable differences in post-rest egg production among the various treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Descriptors: *Chickens--physiology--PH; *Fasting; *Oviposition; *Zinc--administration and dosage--AD; *Zinc Oxide--administration and dosage--AD ; Body Weight; Diet; Time Factors


Meluzzi A; Franchini A; Giordani G; Bertuzzi S (1986). Induction of moult in laying hens. 1. Effects of fasting and of zinc oxide. [Induzione della muta nelle galline ovaiole. 1. Effetti del digiuno e dell'ossido di zinco.] Zootecnica e Nutrizione Animale 12(6): 465-472.

Istituto di Zoocolture, Via San Giacomo 9, 40126 Bologna, Italy.

            NAL Call Number: SF1 Z6

360 Warren layers, at 70 wk of age and 66% lay, were subjected to the following treatments: (1) addition of 2.5% zinc oxide to the diet for 15 days; (2) fasted for 15 days; (3) addition of 1.1% zinc oxide to the diet for 8 days, followed by 1.5% for 7 days; (4) addition of 2.5% zinc oxide to the diet for 8 days; (5) fasted for 8 days. In the 5 groups resp., zero egg production was reached in 6, 6, 9, 6 and 5 days, and 30% production in the next cycle after 56, 56, 36, 22 and 22 days. Egg production in the 2nd cycle was 65.3, 65.7, 60.2, 56.4 and 62.0% resp., and food consumed per kg eggs 3.06, 3.02, 3.32, 3.42 and 3.09 kg (both P<0.01). Egg weight in the 2nd cycle averaged 67.04, 68.20, 68.06, 67.71 and 68.12 g resp. (P< 0.05), Haugh units 74.59, 73.55, 73.67, 73.64 and 71.35% (P<0.01), and egg shell thickness 347.2, 352.0, 352.7, 349.9 and 348.6 micro m (P< 0.01).

Descriptors: laying performance, moult, zinc, hens, starvation, egg production

            Copyright© 2002, CAB International


Naber EC (1983). Use of low sodium diets and low sodium-low protein diets for recycling of laying hens fed for intervals of 4, 6 or 8 weeks in a low light environment. Proceedings of the Maryland Nutrition Conference for Feed Manufacturers, p.7-12.

Dep. Poultry Science, Ohio State Univ., Ohio Agricultural Research and Development Center, Columbus, Ohio 43210, USA.

            NAL Call Number: 389.9 UN342

From results of an experiment with 1200 Hy-Line W-36 laying hens initially 70 weeks old, it was concluded that low-sodium diets can be used to prepare hens for a second period of egg production with results comparable to those obtained by forced moulting. The low-Na diet is easy to administer and avoids criticisms from people concerned with animal welfare. However, this method can be used only when low-Na drinking water is available and the Na content of the diet can be reduced to 0.05% or less. Results were better with a diet low in Na only than with a diet low in Na and protein. Maximum egg production response occurred with diets used for 6 weeks and was not further improved by an 8-week feeding period. 2 ref.

Descriptors: sodium, intake, hen feeding, egg production, protein intake

            Copyright© 2002, CAB International


Naber EC; Latshaw JD; Marsh GA (1980). Use of low sodium diets for recycling of laying hens. Poultry Science 59(7): 1643.

Dep. Poultry Science, Ohio State Univ., Columbus, OH 43210, USA.

            NAL Call Number: 47.8 AM33P

Two trials were to study the effect of low-sodium diets on recycling of hens for subsequent reproductive performance. In the first trial the low-Na diets, with or without KCl supplements, were tested. The last egg was laid 11 to 15 days following dietary treatment. For the 6-week period on the experimental diets, feed intake was reduced by 50 or 60%, bodyweight was reduced by 300 g, and 97% of the hens were in an active molt. Potassium supplements did not change the effect of the low-Na diet. In the second trial, both a low-Na and a low Na- low-protein diet were tested in a 6 or 13h daylight environment and compared to a conventional forced moulting procedure. Both diets stopped egg production, induced moult, reduced bodyweight, and limited feed intake in a similar manner. The 6h daylight accentuated these effects when compared to the 13h daylight. During 32 weeks following treatment, egg production and egg specific gravity were significantly increased by use of the low-Na diet, the low Na-low protein diet, or the conventional forced moulting procedure over that of non-recycled controls. Egg weight and albumen thickness were not affected by the treatment.

Descriptors: sodium, hen feeding

            Copyright© 2002, CAB International


Naber EC; Latshaw JD; Marsh GA (1984). Effectiveness of low sodium diets for recycling of egg production type hens. Poultry Science 63(12): 2419-2429.

Dep. Poultry Science, Ohio State Univ., Columbus, OH 43210, USA

            NAL Call Number: 47.8 AM33P

Egg type hens were recycled by the use of low sodium diet treatments compared to a conventional forced-molt procedure and an unrecycled control. Use of a low sodium diet containing .02 to .06% sodium for 6 weeks with reduction in daily photoperiod resulted in improvements in egg production, egg specific gravity, and albumen thickness similar to those of a forced-molt group in three separate experiments. Egg production was increased 11 to 13%, egg specific gravity was increased by .002 to .004, and albumen thickness was increased by 2 to 8 Haugh units over the 32-week post-treatment period for both treatments. Hens fed the low sodium diet for 3.5 or 4 weeks did not respond as favorably as hens fed this diet for 6 weeks. Eight weeks on the low sodium diet did not further improve performance. Results comparable to the forced-molt procedure were achieved with a decline in egg production at .03 to .07% sodium in the diet, a decline in feed intake at .03 to .07% sodium, a loss in body weight at .03 to .10% sodium, and an increase in molt score at .03 to .11% sodium during the experimental period. During the post-treatment period, results comparable to the forced-molt procedure were obtained for egg production increase at .03 to .08% sodium, for egg specific gravity increase at .03 to .12% sodium, and for egg albumen thickness increase at .03 to .12% dietary sodium. Mortality was unchanged.

Descriptors: Animal Feed, Chickens--physiology--PH, Diet, Sodium-Restricted, Oviposition , Body Weight, Dietary Proteins--administration and dosage--AD


Nesbeth WG; Douglas CR; Harms RH (1976). The potential use of dietary salt deficiency for the force resting of laying hens. Poultry Science 55(6): 2375-2379.

Dep. Poultry Science, Florida Agricultural Experiment Station, Gainesville, Fla. 32611

            NAL Call Number: 47.8 AM33P

Two experiments with a total of 240 laying hens caged individually were to evaluate dietary salt deficiency as a tool for the forced resting of laying hens. The control group had a maize and soya diet with 0.25% salt added. Another group had a maize and soya diet with no added salt for 6 weeks then returned to the control diet. The third group was subjected to the force moulting technique recommended by Wilson et al. (NAR 40, 4216). The drinking water, given freely, and the basal diet had Na 26 and 270 mg/kg. Feed intake and bodyweight of hens on the low-salt diet or force-moulted decreased significantly and egg production ceased during the moult. The reproductive organs of hens given the low-salt diet regressed to about 25% of the original size. When hens returned to the control feed, recovery was complete with significant increases in egg weight and egg specific gravity for hens on treatment 2. Egg production was greater for hens which got low salt and those force-moulted than for the control hens after the moult period.

Descriptors: egg production, hens, salt deprivation, forced resting

            Copyright© 2002, CAB International


Oliveira RM de; Bertechini AG; Oliveira AIG de (1997). Egg quality of commercial laying hens submitted to four methods of moulting induction. [Qualidade dos ovos de poedeiras comerciais submetidas a quatro metodos de inducao de muda.] Ciencia e Agrotecnologia 21(1): 103-108.

Universidade Federal de Lavras (UFLA), CP 37, 37200-000, Lavras, MG, Brazil.

            NAL Call Number: S15 C53

A trial was carried out with 192 commercial laying hens (ISA Babcock B-300), 64 weeks of age and averaging 75% production, housed in pairs, in wire cages. The following treatments were applied: (1) 5 days with no ration; (2) 10 days with no ration; (3) 3 days with no ration followed by feeding with broken corn and sorghum grains for 9 days, and (4) feeding with a ration with a high level of zinc for 12 days. All treatments gave statistically similar results for egg specific gravity, egg weight, albumen height and Haugh Units. Shell thickness, shell weight and specific gravity increased significantly (by 0.29%, 5.35% and 7.37%, respectively) from 68 to 73 weeks of age. Shell thickness was greatest with treatment (3) and this treatment is recommended for obtaining the best egg quality in second cycle production.

Descriptors: age, hens, egg quality, egg weight, poultry, egg albumen, eggs, egg shell, diets, zinc, moulting, feeding, management, plane of nutrition

            Copyright© 2002, CAB International


Oliveira RM de; Hossain SM; Oliveira AIG de; Bertechini AG (1996). Methods of inducing molting in commercial laying hens. [Metodos de inducao de muda em poedeiras comerciais.] Ciencia e Agrotecnologia 20(3): 394-400.

            NAL Call Number: S15 C53

To improve performance in the second production cycle of laying hens, a trial was carried out with six methods of induction of molting. A total of 288 commercial laying hens, 64 weeks old and averaging 75% of production, housed in pairs in wire cages, were used. The treatments were the following: five days without ration (T1); ten days without ration (T2); three days without ration followed by feeding with broken maize and sorghum grains for nine days (T3); ration without limestone or salt for twelve days (T4); ration with a high level of zinc for twelve days (T5); and ration with a high level of iodine for 12 days (T6). Maize and soyabeans were used as the basal diet. Treatments did not differ statistically (P > 0.05) with regard to egg production. T1 and T4 showed lower feed intake and best feed conversion per dozen eggs. T2, T4 and T6 showed higher average egg weight. T1 and T4 showed best performance in the second cycle of egg production.

Descriptors: egg production, egg weight, molting, induction, starvation, maize, grain, limestone, salt, zinc, iodine, feed intake, feed conversion efficiency, poultry


Parsons CM; Ridlen SF (1984). Nutritional comparison of force molting methods. Poultry Adviser 17(9): 57-60.

Poultry Cooperative Extension Service, USDA, Univ. Illinois, Urbana-Champaign, 1301 West Gregory Drive, Urbana, Ill. 61801, USA.

            NAL Call Number: SF481 P622

A short review compares 3 types of diet for forced moulting of laying hens. Those are a low-protein molting diet based on maize, a pullet-developer moulting diet with protein 14 to 16%, and a low-sodium diet, all used in USA.

Descriptors: moult, diets, hens

            Copyright© 2002, CAB International


Pavlovski Z; Milovanovic M; Masic B (1992). Periodic induced rest in layers. (Periodicno indukovanje odmora kod nosilja konsumnih jaja.) Peradarstvo 27(7-9): 64-69.

            NAL Call Number: SF481 P4

In a pilot trial Isabrown layers kept in individual cages 80 weeks of production were divided in 4 groups with 29 birds in each group. Group A was a control group (no induced rest), and in other experimental groups some rests were induced by low-sodium diet (group B after 40 weeks of production, group C after 28 and 56 weeks of production, group D after 20, 40 and 60 weeks of production). Average number of eggs per hen housed was the highest in group C (373 eggs), and the lowest in group D (352 eggs), but the difference was not significant. The results obtained in this pilot trial have suggested that periodic rest induced by low-sodium diet is not so efficient in improving performance of layers in a longer production period.

Descriptors: layer chickens, rest, eggs, laying performance, animal products, biological rhythms, birds, chickens, domestic animals, domesticated birds, galliformes, livestock, performance


Praharaj NK; Rao SVR; Raju MVLN; Chawak MM; Mishra SK; Mohapatra SC (1994). Combined feeding of zinc, iodine and salt-free diet for inducing moult and its effect on subsequent performance of layer. Indian Journal of Poultry Science 29(2): 142-145.

Project Directorate on Poultry, Rajendranagar, Hyderabad 500 030, India.

            NAL Call Number: SF481 I5

300 White Leghorn hens, 67 weeks old, were studied. A standard layer diet devoid of salt but supplemented with iodine 3750 (SFI), zinc 7500 (SFZ) or iodine 2500 + zinc 5000 mg/kg (SFIZ)and a standard diet with salt and supplemented with iodine 3750 + zinc 7500 mg/kg (IZ) was used to induce moulting, and compared with a control diet that did not induce moulting. The results showed a significant decline in egg production in all groups during the 17 days of moulting. the effect being more pronounced in SFZ hens. Body weight loss during moulting and gain in weight during the subsequent laying cycle were also highest in SFZ hens, followed by the SFIZ, SFI and IZ groups. During the post-moult period, hen-housed egg production and feed conversion efficiency were significantly higher in all the moulted groups compared with the controls, but with no differences among the moulted groups. Egg weight was significantly higher in the IZ group followed by the SFI group. Eggs produced by moulted groups were significantly superior to those from controls for albumen index and Haugh unit score. 12 ref.

Descriptors: zinc, iodine, supplements, moulting, induction, sodium chloride, body weight, egg production, egg quality, feed conversion efficiency

            Copyright© 2002, CAB International


Ross E; Herrick RB (1979). Forced rest induced by molt or low-sodium diet on subsequent hen performance. Poultry Science 58(4): 1101.

Dep. Animal Sciences, Univ. Hawaii, 1800 East-West Road, Honolulu, HI 96822, USA.

            NAL Call Number: 47.8 AM33P

Descriptors: egg production, molting, sodium intake


Ross E; Herrick RB (1981). Forced rest induced by molt or low-salt diet and subsequent hen performance. Poultry Science 60(1): 63-67.

Dep. Animal Sciences, Univ. Hawaii, Honolulu, Hawaii 96822, USA

            NAL Call Number: 47.8 AM33P

Four strains of laying hens (1534 birds), were force-moulted by one of 2 procedures when 66 weeks of age. In treatment 1 birds had the feed withheld for 10 days and day length reduced to 8 h, after which a low-protein diet was given. In treatment 2 birds were fed on a low-salt diet, containing 0.13% sodium, and subjected to the same lighting as those in treatment 1. Egg production of hens on treatment 2 decreased gradually to 13% after 38 days whereas those on treatment 1 were completely out of production in 7 days. After 5 weeks all birds were restored to the standard layer diet and 14 h light daily. Hen-day egg production of birds on treatments 1 and 2 was 63.1 and 55.2%, respectively, from 72 to 102 weeks of age, with feed intakes of 1.90 and 2.19 kg/12 eggs. Bodyweight gain, egg specific gravity and egg weight for birds on treatment 2 were also less than on treatment 1. The cause was attributed to a higher dietary Na content than the 0.044% intended.

Descriptors: egg production, moult, sodium, intake, hen feeding, low-sodium diet

            Copyright© 2002, CAB International


Salyi G (1985). Decrease in egg production caused by insufficient sodium chloride (NaCl) supply in a commercial laying flock. [Hianyos konyhaso- (NaCl-) ellatas okozta tojastermeles- csokkenes nagyuzemi tojotyukallomanyokban.] Magyar Allatorvosok Lapja 40(4): 221-224.

Tabornok u. 2., 1149 Budapest, Hungary.

            NAL Call Number: 41.8 V644

A significant decrease in egg production, accompanied by cannibalism and molting occurred in a commercial flock of about 136 000 hens. Sodium in the feed varied between 0.053 and 0.08% and the lowest rate of egg production, varying between 15.8 and 30.6%, occurred 3-4 weeks after consuming this feed. Egg production increased again after supplementation of diets with NaCl. It is concluded that giving diets low in NaCl is not a safe and effective method of force-moulting in preparation for a second production cycle. 15 ref.

Descriptors: sodium chloride, deficiency, egg production, nutrient deficiencies

            Copyright© 2002, CAB International


Santoprete G; Fini MA (1984). Changes in the zinc content of eggs of hens subjected to induced moult. [Variazioni del contenuto di zinco nelle uova di galline sottoposte a muta forzata.] Avicoltura 53(3): 45-47.

Cattedra di Merceologia, Pisa Univ., Pisa, Italy.

            NAL Call Number: 47.8 R523

In egg yolks of hens given diets with 1% zinc oxide to induce moult, Zn increased from 49.8 to 93.9 mu g/g after 17 days. Zn in albumen was unchanged. 18 ref.

Descriptors: zinc, eggs, moult

            Copyright© 2002, CAB International


Sarica M; Ozturk E; Karacay N (1996). Effects of different forced molting methods on egg production and egg quality traits. [Degisik zorlamali tuy dokum programlarinin yumurta verimi ve yumurta kalitesi uzerine etkileri.] Turk Veterinerlik ve Hayvancilik Dergisi 20(2): 143-150.

Ondokuz Mayis Universitesi, Ziraat Fakultesi, Zootekni Bolumu, Samsun, Turkey.

            NAL Call Number: SF1 D57

This study was conducted to compare fasting or feeding a high-zinc diet as procedures to induce cessation of laying. Ross Brown hens, aged 68 weeks, were used for the experiment. Daily light was supplied in the molting period. Three groups were fasted (no feed and water); 2 other groups received a diet with 10 000 or 15 000 p.p.m. zinc for 9 days. For the 5 groups, body weight loss 10 days after initiation of treatment was 13.72, 15.64, 14.16, 15.39 and 16.37% respectively, egg production during the resting period 7.19, 3.22, 2.61, 4.73 and 5.65, and egg production in the 2nd laying period 108.30, 109.21, 114.86, 108.63 and 113.06 (in 161 days). There were no significant differences in egg production among the treatments. Very low mortality was noted in all groups with no apparent differences. For the 5 groups, survival rate was 94.99, 96.69, 96.23, 98.23 and 96.38% respectively in the resting period, and 94.88, 96.87, 95.52, 96.92 and 92.77 in the 2nd laying period. For the 5 groups, egg weight averaged 68.83, 68.10, 68.25, 69.07 and 69.12 g respectively and shell thickness 335.27, 320.72, 337.67, 320.63 and 336.45 micro m. Egg shell strength, shell thickness and yolk index were different (P<0.05) among groups. It is suggested that any of the procedures can be used with commercial laying hens.

Descriptors: hens, fasting, zinc, supplements, molting, induction, egg production, egg weight, egg quality, egg shell, body weight, change, poultry


Setioko AR; Coligado EC (1987). Effect of forced molting treatments on the productivity of itik [mullard] and Tsaiya ducks [Philippines]. Philippine Journal of Veterinary and Animal Sciences 13(4): 46-47.

            NAL Call Number: SF1 P53

While molting has been widely employed on commercial duck farms as a production technique for many years in some countries, very little published information is available concerning production responses to specific methods of inducing the molt. This study was designed to investigate the effect of high level of dietary zinc and the system of feed and water deprivation as specific techniques of forced molting in layer ducks on their production performance as well as the physiological behavior such as feather shedding, replacement and growth of new feathers. One hundred forty four layer ducks and 24 drakes were used in this study. Seventy two ducks and 12 drakes were the Tsaiya (a Taiwan egg type duck) and an equal number were the itik (local Mallard). Two levels of zinc oxide (15 g/kg and 30 g/kg diet) and feed and water deprivation methods were compared. Data from this study showed that forced molted ducks generally had higher total egg production as compared to the control. The level of 15 g/kg zinc oxide technique was found to be more beneficial method for forced molting in itik and Tsaiya ducks. The feed and water deprivation technique caused too serious bodily stress particularly in Tsiaya ducks, so it took a longer time before they recovered and returned to egg production.

Descriptors: ducks, productivity, molting, zinc, egg production, restricted feeding, Philippines, agriculture, animal feeding, animal production, animals, anseriformes, Asia , biological rhythms, birds, domestic animals, domesticated birds, elements , feeding, feeding systems, game, game birds, heavy metals, industrial pollutants, injurious factors, metals, nutrition, pollutants, poultry, production time, timing, vertebrates, zootechny


Shippee RL; Stake PE; Koehn U; Lambert JL; Simmons RW, III (1979). High dietary zinc or magnesium as forced-resting agents for laying hens. Poultry Science 58(4): 949-954.

Dep. Nutritional Sciences and Statistics, Univ. Connecticut, Storrs, Conn. 06268

            NAL Call Number: 47.8 AM33P

Single-Comb White Leghorn hens aged 58 weeks in 5 groups of 18 were force-moulted, by deprivation of water for 48 h and of feed for 9 days then free intake of diet with 10% crude protein, or by being given in their laying diet for 14 days 1% zinc as acetate or oxide, or 2% magnesium as acetate or oxide. The Zn as acetate or oxide depressed feed intake and stopped egg laying within 6 days; then the hens resumed production in the next 24 weeks as they did after deprivation of feed and water. Mg was less effective; egg laying did not stop completely and the eggs had lower Haugh units and d and thinner shells. 11 ref.

Descriptors: feed intake, hens, egg production, animal feeding, toxicity, moulting, magnesium, zinc

            Copyright© 2002, CAB International


Sloan, DR; Harms, RH (1992). Research note: Effect of removing salt from the diet of broiler breeder hens. Poultry Science 71(4): 775-777.

University of Florida, Gainesville, FL

NAL Call Number: 47.8 AM33P

Two 28-day experiments were conducted utilizing 75-wk-old Arbor Acres broiler breeder hens to determine the effect of removing salt from the diet. Birds in Experiment 2 had been force-rested at 60 wk of age but were in production (65% hen-day) at experiment initiation. All hens received a corn-soybean meal diet either with or without added salt. Egg production was significantly reduced in both experiments by the end of the 4th wk for birds fed the diet with no added salt. However, egg production did not cease in hens receiving the diet with no added salt. Egg weights from hens receiving the diet with no added salt were significantly reduced by the end of Week 2 in Experiment 1 and Week 3 in Experiment 2. Specific gravity was only intermittently affected by dietary salt removal. Birds receiving no added salt lost 541 and 580 g in Experiments 1 and 2, respectively. Birds receiving added salt diets gained 55 and 23 g in Experiments 1 and 2, respectively. Removing salt from the diet was not an acceptable method of force-resting broiler breeder hens.

Descriptors: broilers, hens, salt, egg production, egg weight, specific gravity, feed intake, forced rest


Stevenson MH; Jackson N (1984). Comparison of dietary hydrated copper sulphate, dietary zinc oxide and a direct method for inducing a molt in laying hens. British Poultry Science 25(4): 505-517.

NAL Call Number: 47.8 B77

The experiment lasted for seven 28-d periods. Laying hens of two breeds were allocated to 10 treatments. For the first 28-d period all birds were offered the control diet and then the following dietary treatments applied: a control group not molted, one group molted traditionally, 4 groups molted using CuSO4- and 4 using ZnO-containing diets. After the molting treatments the hens were offered the control diet for the remainder of period 2 and for a further five 28-d periods. The treatments applied during period 2 significantly reduced food intake, body weight, egg number, total egg weight and efficiency of food conversion. On returning to the control diet, there were no significant differences in cumulative food intake (periods 3 to 7). Body weight had returned to the same value as the control group by the end of period 3. Dietary treatments significantly reduced the efficiency of food utilisation during periods 3 to 7 and 1 to 7 inclusive. For periods 1 to 7 inclusive the birds force-molted using CuSO4 and ZnO gave on average greater egg numbers and total egg weights than those molted traditionally. The Haugh unit score was significantly improved after molting. Egg Zn concentrations were increased by the 14-d ZnO treatments. The use of a diet containing CuSO4 (2 g added Cu/kg for 7 d) was as effective as one containing ZnO (20 g added Zn/kg for 14 d) and both were superior to a traditional force-molting technique.

Descriptors: hen feeding, molting, zinc oxides, copper sulfate, feed intake, egg production, egg shell thickness, egg albumen, haugh units


Verheyen G; Decuypere E (1991). Egg quality parameters in a second and third laying year as a function of the moulting age, strain and moulting method. Archiv fur Geflugelkunde 55(6): 275-282.

Laboratorium voor Fysiologie der Huisdieren, Kardinal Mercielaan 92, 3030 Herverlee, Belgium

            NAL Call Number: 47.8 AR2

600 White Leghorn Hisex and 600 Warren SSL pullets in battery cages were subjected to forced moulting by means of starvation or a high-zinc diet at 54, 62, 70 or 78 wk of age. Age at moulting and strain had a highly significant effect on egg weight in the 2nd year of production, with hens treated at 54-62 wk and Warren hens showing the best performance. There was a significant age x strain interaction, but method of moulting did not affect egg weight. The egg shell quality in the 2nd yr improved after forced moulting for Hisex hens, irrespective of age, but that of Warren hens did not. The incidence of broken eggs in the 2nd laying year was 2.64, 2.71. 3.02 and 3.15% in birds forced to moult at the 4 ages resp., and in the 3rd yr it was 3.19, 3.65 and 4. 08% in groups 1, 2 and 3. Hisex birds produced a significantly greater percentage of broken eggs than Warren hens. Albumen quality was generally better in white than in brown eggs, and the Haugh unit score decreased with increasing age, in particular for Warren birds. Albumen quality appeared to be negatively correlated with egg weight in older birds subjected to forced moulting.

Descriptors: laying performance, moult, strain differences

            Copyright© 2002, CAB International


Verheyen G; Helsen J; Decuypere E (1990). Accumulation of zinc in egg yolk, ovarian follicles and organs after forced resting by high dietary zinc. British Poultry Science 31(1): 147-154.

Catholic University of Leuven, Laboratory for Physiology of Domestic Animals, Kard Mercierlaan, Belgium.

            NAL Call Number: 47.8 B77

1. Eighteen Warren SSL hens of 71 weeks of age were forced-molted by ad libitum feeding of a high-zinc diet (10,000 ppm zinc for 2 days followed by 5,000 ppm zinc-supplement diet for 4 days). From the start of the treatment, eggs were collected and 3 hens were slaughtered on days 0, 2, 3, 4, 5 and 6 of the study. 2. Zinc analyses were carried out on the different components of the eggs and on liver, pancreas, kidney, different yolky follicles of the ovary and various segments of the oviduct. 3. Seven-, six- and threefold increases in zinc concentration were found in pancreas, liver and kidney, respectively. 4. The shell gland and isthmus, but not the magnum, also showed slight but significant increases in Zn content. 5. Zinc accumulation was also high and almost identical in ovarian follicles F1 to F4 but slightly less in F5 and F6 follicles. 6. In the egg, a significant increase in zinc concentration was only observed in the yolk.

Descriptors: Chickens--metabolism--ME, Egg Yolk--analysis--AN, Ovarian Follicle --metabolism--ME, Zinc--pharmacokinetics--PK , Kidney--analysis--AN, Kidney--metabolism--ME, Liver--analysis--AN, Liver --metabolism--ME, Ovarian Follicle--analysis--AN, Oviducts--analysis--AN, Oviducts--metabolism--ME, Pancreas--analysis--AN, Pancreas--metabolism--ME , Tissue Distribution, Zinc--analysis--AN


Whitehead CC; Sharp PJ (1976). An assessment of the optimal range of dietary sodium for inducing a pause in laying. British Poultry Science 17(6): 601-611.

ARC Poultry Research Centre, King's Buildings, West Mains Road, Edinburgh EH9 3JS, UK.

            NAL Call Number: 47.8 B77

Laying hens were fed on a diet with Na 0.9 g/kg until 34 weeks of age, then groups were fed on diets with 0.2, 0.3, 0.4, 0.5, 0.6 or 0.9 g/kg for 16 weeks before that with Na 0.9 g/kg was reintroduced for all birds. Egg production and feed intake were depressed by the low-Na diets in proportion to the Na content. Birds receiving Na 0.3 to 0.6 g/kg diet lost weight initially but subsequently gained; birds receiving 0.2 g/kg diet lost weight continuously. In birds on Na 0.2 g/kg diet, the reproductive organs completely regressed, whereas the organs resembled those of point-of-lay pullets in birds on Na 0.3 or 0.4 g/kg. When the control diet was reintroduced, birds which had low-Na diets resumed normal egg production and feed intake and regained bodyweight. The range of dietary Na for inducing a pause in egg laying is 0.3 to 0.4 g/kg.

Descriptors: egg production, nutrient requirements, hens, feed intake, moult, induction, sodium

            Copyright© 2002, CAB International


Williams JB; Etches RJ; Rzasa J (1985). Induction of a pause in laying by corticosterone infusion or dietary alterations: effects on the reproductive system, food consumption and body weight. British Poultry Science 26(1): 25-34.

Sta. Recherches Avicoles, Centre INRA de Tours-Nouzilly, 37380, France.

            NAL Call Number: 47.8 B77

A pause in laying was induced in hens by infusing 30 micro g corticosterone/h, feeding diets deficient in calcium or sodium, or by food and water withdrawal. In hens infused with corticosterone, food consumption remained high and body weight was unchanged, although liver weight doubled. The other treatments were associated with a decline in food consumption and a loss in body weight, but liver weight was unchanged. Ovary weight was reduced most severely in hens given corticosterone, but the number of follicles weighing >12 mg was not altered by any of the treatments. A decrease in the number of large yolk-filled follicles was matched by an increase in the number of small ones. All treatments resulted in an increase in the number of atretic follicles, an elevation of plasma corticosterone concentration within the normal physiological range, and a decrease in plasma LH concentration.

Descriptors: molt, induction, corticosterone, corticoids, feed restriction, nutrition, sodium deficiency, calcium deficiency, water restriction


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October 23, 2002