Forced Molting Research Articles

Physiological Changes in Caged Layers During a Forced Molt: 2. Gross Changes in Organs , , ,

The effects of forced molting on body weight and the absolute and relative weights of the liver, ovary, oviduct, right adrenal, and spleen were studied. White Leghorn hens which were reared and maintained under commercial conditions were force molted by reducing daylength as well as by withdrawing feed and water. This procedure induced a pause in egg production within one week of the initiation of feed removal. Four trials were conducted. In Trial 1 the hens were sampled at weekly intervals for 56 days beginning at the time feed was removed. In Trials 2, 3, and 4 the hens were sampled either daily or on alternate days for up to 22 days beginning at the time of feed removal.The absolute and relative weights of the liver, ovary, and oviduct were decreased significantly. Body weight decreased consistently. No consistent trend over the four trials was found in the absolute or relative weights of the right adrenal or the spleen.

Effect of Methods to Control Egg Production on the Economical Profit in the Laying Hen

The egg price in Japan has been showed a fluctuating curve like the low price occurred from April to August and the higher price from September to December. Therefore, as a way of improving economical profit, controlled egg production method was studied, which was intended to improve feed conversion ratio in the lower egg price period and egg production in the higher egg price period. The experiments were conducted Yamanashi, Shiga and Gifu prefectural poultry experimental station with 540 commercial layers. They were hatched April 1975 and reared until 48 weeks of age with the same management. Then they were divided into 3 groups of a control group and two experimental groups. The experimental period was 40 weeks, i. e., from 48 to 88 weeks of age. The control group was fed commercial layer's diet (CP 16%) ad libitum. One of experimental groups (Restrict group) was fed the diet restrictively at 90% of feed consumption of the control group from 48 to 68 weeks of age and thereafter fed ad libitum. Another experimental group (Restrict & fast group) was also fed the diet restrictively as those of Restrict group from 48 to 64 weeks of age, afterwards was fasted for 3 weeks, which resulted in forced molting, and then refed the diet ad libitum from 68 to 88 weeks of age. The economical profit was estimated with the formula, raw profit per day per bird=(egg price×egg production weight per day per bird)-(60 Yen per kg×Feed consumption per day per bird). The egg price was used fluctuating egg price which was calculated with the data of 1973-1977.1. In restricted feeding period, the Restrict group was 1.6% lowerr than the control group in egg production rate, but was superior 0.11 in feed conversion ratio and 0.2 Yen per day per bird in raw profit to the control group. However, after the group was returned to ad libitum feeding, compensatory egg production did not be observed in the group, when compared the economical profit in the total period, the Restrict group was similar with the control group.2. In restricted feeding period, the performance of the Restrict & fast group was similar as those of the Restrict group. After fasting period, the peak of egg production rate of the Restrict & fast group was raised up to 80.3% and this time was coincided with the higher egg price period. Therfore the raw profit per day per bird of the Restrict & fast group was 1.34 Yen higher than the control group from 68 to 88 weeks of age. As a result, in total experimental period, the Restrict & fast group was 2.3% lower in egg production rate than the control group, but was superior 0.13 in feed conversion ratio and 0.4 Yen per day per bird in raw profit to the control group.3. Egg shell quality was not influenced by restricted feeding, but was improved siginificantly by forced molting.

The Influence of Force Molting on the Incidence of Uncollectable Eggs

Two experiments were conducted to determine the influence of force molting on egg shell quality. Approximately 15,000 Honegger and 15,000 Babcock hens, 17 months of age, were force molted using conventional methods. Just prior to force molting, the incidence of shell-less, ultra-thin shell and thin-shell eggs (uncollectable) was determined. Sheets of metal were hung at random beneath the cages of 800 birds in each population to catch all eggs that dropped through the cages. Fifty hard-shell eggs were collected at 2-hr. intervals from 6:00 a.m. to 6:00 p.m. and specific gravity and egg weight were determined. The above procedure was repeated at 8, 13 and 24 weeks after the molt.The hens in both experiments were laying an average of 12.6% uncollectable eggs prior to molt. The incidence was reduced to 2.9%, 1.4% and 8.1% for the 8, 13 and 24-week post-molt period, respectively. Egg weight significantly increased at the 8-week (experiments 1 and 2) and 24-week (experiment 1) test periods. Egg specific gravity was increased only by the 13-week test period in experiments 1 and 2. Time of oviposition had no influence on the degree of increase in specific gravity or weight of eggs caused by force molting.It was concluded that the incidence of uncollectable eggs can be significantly reduced at least 3 months by force molting.

Effects of Restricted Feeding during the Rearing Period and Induced Moulting in Laying Period on Laying Performance of Hens

The collaborative experiment in 8 prefectural experiment stations was carried out to investigate the effect of restricted feeding in rearing period and induced moulting in laying period on prolonged egg production of hens.Chicks were hatched in Spring and Autumn in this experiment. Eight experiment stations were divided into two groups and in Spring, hatching was assigned to Yamaguch, Ehime, Kumamoto and Miyazaki station and in Autumn, it was done to Tottori, Hiroshima, Oita and Kagoshima station, respectively. In each experiment station, chicks were divided into two groups at 4 weeks of age. One group was fed ad libitum and the other group was fed restricted, in which feed restriction rate was 60per cent feed of the control group from 4 weeks to 18 weeks of age. The ful-fed groups and the restricted feeding groups were divided into 4 sub-groups at 20 weeks of age, respectively. In two sub-groups, forced moulting was conducted only one time at 92 or 80 weeks of age and in the other two-sub groups, it was done twice at 68 and 96 or 56 and 96 weeks of age. They were reared until 128 weeks of age and production trait and economical trait were observed.Age at the first egg was delayed in the restricted feeding group than in the fullfed group. But, the weight of first egg was havier in restricted feeding group than in full-fed group. Body weight of layer was lighter in restricted feeding groups than in the fullfed groups at 44 weeks of age. The rate of raising was lower in the restricted feeding group than in the full-fed group, but there was no significant differences between them.In the full-fed group, egg production rate from 20 to 128 weeks of age was higher in earier forced moulting group than in later forced moulting one. And economical trait which were estimated by feed consumption from raising to laying period per kg of egg production was showed same tendency as the rate of egg production. On the other hand, the different result was observed in the restricted feeding groups. There was no significant relation between the age of forced moulting and egg production rate or economical trait. Furthermore, there were no significant differences in both traits among all restricted feeding groups and the full-fed group which was showed highest performance.

EFFECT OF BRINING AND COOKING PROCEDURE ON TENDERNESS OF SPENT HENS

ABSTRACTThree experiments were conducted to determine the effects of brining and cooking procedures on the tenderness of spent hens. These experiments included tests on the effect of brining and cooking procedure on 84‐wk‐old hens; effect of brining on the tenderness of 39, 84 and 108‐wk‐old hens; and the effect of force molt or low salt diet as well as brining on the tenderness of meat from 108‐wk‐old hens. Shear values were significantly lower for both light and dark meat from brined hens. Light meat from both brined and unbrined birds was significantly more tender than dark meat. Cooking procedures did not appear to affect tenderness of light meat, but smoked dark meat was significantly more tender than oven‐roasted dark meat. Feeding a low salt diet or force molting did not significantly affect the tenderness of meat from 108‐wk‐old hens.

The Potential Use of Dietary Salt Deficiency for the Force Resting of Laying Hens

Two experiments using a total of 240 laying hens housed in individual cages were conducted to evaluate dietary salt deficiency as a potential tool for the force resting of laying hens. The control group of hens received the corn-soy diet with 0.25% added salt. Another group of hens received a basal corn-soy diet with no added salt for six weeks then was returned to the control diet. The third group was subjected to the force molting technique recommended by Wilson et al. (1969). The drinking water, given ad libitum, and the basal diet contained 26 p.p.m. and 270 p.p.m. sodium, respectively. Hen weight, feed consumption, egg production, egg weight and egg specific gravity were recorded throughout each experiment.Feed consumption and body weight of hens receiving the low salt diet (Treatment 2) or forced molted (Treatment 3) decreased significantly and egg production ceased during the molt period. The reproductive organs of hens fed the low salt diet regressed to about 25% of the original size. When hens were returned to control feed, recovery was complete with significant increases in egg weight and egg specific gravity for hens on treatment two. Egg production was significantly higher for both the hens which received low salt and those force molted, compared to the control birds during the post molt period.The results of the experiments indicated that dietary salt deficiency is effective for the force resting of laying hens.

An Attempt to Force Molt Small Egg-Type Pullets

Small 1.1 kg. egg-type pullets having the sex-linked dw dwarfing gene were more resistant to a force molting program started at 11 months of age than were their 1.4 kg. non-dwarf counterparts. Water deprivation appeared to prevent egg production sooner in the dwarfs than in the non-dwarfs but egg production eight weeks after initiation of the force molt program was 46% versus 64% for the non-dwarf pullets.

Effect of Force Molting and Induced Hyperthyroidism on the Depletion of DDT Residues from the Laying Hen

Experiments were conducted to determine the relationship between dosage levels of DDT and retention of residues in the egg and depot fat of hens, to determine if force molt by feed restriction would increase the rate of elimination of DDT from egg and tissue, and to determine if hyperthyroidism induced by feeding thyroxine would increase the rate of elimination of DDT from the egg or tissue of the hen.Hens which consumed 20, 30 and 40 p.p.m. DDT of daily feed uptake for five days stored the DDT in their depot fat. Concentrations of residues in eggs were approximately 25 to 30 percent of residue concentrations found in the depot fat. Depletion of DDT residues from the eggs and depot fat of hens follows the kinetics of a first order reaction. Also, the depletion rate constant does not depend upon the concentration of residues present in the fat.The half-lives of DDT residues in depot fat and eggs were 7.3 and 7.6 weeks respectively. When hens were force molted by starvation, half-lives of DDT residues for depot fat and eggs decreased to 5.9 and 5.0. Feeding of 0.45 mg./day of thyroxine for 71 days significantly decreased the half-live of residues in depot fat to about 2.5 weeks and in eggs to 3.8 weeks. Force molting in combination with the thyroxine feeding did not improve the half-live of DDT residues over feeding thyroxine alone.

Forced Molting in Pullets and Its Effect on Subsequent Egg Production in Layers

Effects of forced molting induced by methalibure administered either at 3 months or 7 months after the age of 50% egg production upon subsequent egg production were investigated.In the group treated at earlier age the level of egg production after the recovery from temporal cessation of egg laying was more or less similar to that of non-treated control, while the group treated at older age showed a marked rebounding of egg production and continued higher production level throughout the testing period (Fig. 2).Approximately 10% increase in the income through egg marketing can be expected by the use of forced molting conducted at 7 months after the age of 50% production, when the price of eggs is lowest.The degree of molting by methalibure administration seems to be dependent on the age of pullets or the stage of egg production, since the molting appeared in the primary feather was less severe in the group treated at the earlier age and the recovery to 50% production was hastened in this group in comparison with the group treated 4 months later.

Forced Molting by Methallibure (II)

Forced Molting by Methallibure (II)

Forced Molting by Methallibure (I.C.I. 33, 828), a Non-steroid Anti-gonadotropic Compound(1)

Forced molting by the oral administration of a non-steroid anti-gonadtropic compound methallibure (I.C.I. 33, 828) at the dose of 150p.p.m. for two weeks was compared with the conventional forced molting technique of 9 days starvation. The results obtained are summarized as follows;(1) A complete cessation of egg production was appeared on the third day in methallibure treated hens and on the fifth day in the starved hens.(2) Molting of the primaries started on the sixth day after the administration of methallibure and complete molting was observed on the fourteenth day of the treatment, while in the starved group it started on the fifth day after the starvation began. The rate of molting in the latter proceeded slowly and molting of the primaries in twenty percent of the starved birds were still incomplete on the tenth day of the treatment.(3) Days to 50% production after forced molting were 48 days in the METHALLIBURE gronp and 30 days in the starved group, although the recovery to production first appeared on the 24 th day in the former and on the 20th in the latter.(4) Average rates of second year egg production were 55% and 56% for the starved and methallibure treated group respectively, showing no statistically significant deference. Egg weight, feed conversion, egg qualities and mortality were not significantlly different with each other.Those results suggest that the starvation method for the induction of force molting will be safely replaced by the administration of the methallibure, even in the floor house condition.

Studies on the Forced Molting in Layers

Studies on the Forced Molting in Layers

Dietary Pesticides and Contamination of Yolks and Abdominal Fat of Laying Hens

SURVEYS have shown that chlorinated hydrocarbon pesticide contaminations are widespread and persist in the environment for several years following application. These pesticides are fat soluble, and tend to accumulate in the fatty tissues of hens and in the egg yolk. Hauver (1965) reported that the U.S.D.A. had tested more than 2,000 poultry fat samples for residues and found low levels in chickens, turkeys, ducks, and geese of all ages and in all locations examined.Stadelman et al. (1965) found that exposure to the equivalent of 10 to 15 p.p.m. DDT resulted in 4.6 p.p.m. residue in the egg yolk. The residue remained for 26 weeks after removal of the pesticide from the diet.Many factors which affect pesticide metabolism have been studied in order to develop methods of hastening pesticide depletion from body tissues of poultry. The effects of force molting and dietary protein levels on pesticide depletion were studied…

Starvation and Its Effect on Semen Quality

THE practice of force molting hens has been studied over a long period of time and under various molting programs. Most of these programs employed some form of starvation.A review of the literature does not indicate that force molting procedures have been tried with the male. The object of these trials was to determine the effect of starvation on semen production, sperm quality, and feather molt.METHODS AND PROCEDUREIn the first of two trials, three groups of White Plymouth Rock males, 3, 2, and 1 year of age, were maintained in single bird cages (61 × 61 × 61 cm.) in a house with natural daylight. A randomized complete block design, with families (usually full sibs) as blocks, was used with the control and force molt treatments assigned at random to each age group within a family. A total of 10 families was used.At the beginning of…

Performance of Hens Molted by Various Methods ,

FORCED molting has been studied for many years as a possible method of rejuvenating hens to increase egg production and egg quality. Although recommended by a few poultrymen, Rice (1905) was skeptical that the practice would be profitable.More recent results have been variable and the advantages and disadvantages have been summarized by Cox (1964) and Bell (1965). In addition, force molting has been reported to improve poor fertility in turkeys (Moyer et al., 1966) and to increase the DDT depletion rate in hens (Wesley et al., 1966).The method most commonly used for inducing a molt has been some type of feed and/or water restriction such as that suggested by the Poultry Council of the State College of Washington (1947). Noles (1966) reported that feed and water restriction is an effective method of force molting.Progesterone has been shown to be effective in causing a cessation of lay accompanied .

Second Year Production of Force Molted Hens in the California Random Sample Test

TWO molting experiments were conducted at the Poultry Testing Project, Modesto, California, by the California Poultry Improvement Commission, and the University of California, Davis. The purpose of the two experiments was to detect possible strain-treatment interaction in second year performance of hens held with or without artificial molting, respectively.Previous force molt experiments have shown an increase in rate of egg production, in shell thickness and improvement of albumen quality following the molt (Hansen, 1960). He reported greater improvements in egg quality and production as length of molt increased. A gain of 10 Haugh units immediately after force molting was reported by Snyder and Orr (1960). Marble (1963) reported in an analysis of costs and income that hens can be as profitable in their second year of production as they were in their first year. When 44 separate entries in the New York Random Sample Test were force molted, albumen…

Force Molting (Interruption of Egg Laying) in White Leghorn Hens by the Use of Enheptin (2-Amino, 5-Nitrothiazole)

A FORCE molt to the husbandman means to make hens stop egg laying. This is accomplished with variations in severity by radical diet changes, fasting, and darkness. The object of this practice is to switch the period of productivity in order to accrue later advantages. A procedure for causing molt is described in the Washington Extension Bulletin 323 (1947). It has been shown by Berg and Bearse (1947) that force molting results in the improvement of egg quality characteristics when comparing “just prior” and “after” molt eggs. The force-molted hens were not able to recover the level of pullet-year egg quality characteristics.Van der Meulen (1939) reporting on hormonal control of molt was able to force the molt by oral doses of desiccated pig thyroid. He showed that induced hyperthyroidism precipitates molt and interrupts egg production, the duration of which varies with the season.Previous reports by Hudson and Pino …

Progesterone-Induced Unseasonable Molt in Single Comb White Leghorn Pullets

THE process of molting has long been of interest to poultrymen chiefly because of its incompatibility with egg production. The fact that the best producers are usually the latest to molt is of particular importance to breeders because these hens are often not in egg production for the earlier hatches of the hatching season. Various methods of forced molting usually involving a drastic change of management, i.e., limiting feed, or light, or withholding water have long been used. These methods are not usually effective on all birds and generally result in loss in body weight during the molting period following the change of management.Numerous workers have demonstrated that molting can be produced by hypophysectomy (Mitschell, 1929; Hill, Corkill and Parkes, 1934) and by the administration of thyroid by feeding (Van der Meuhlen, 1939). Further evidence that the thyroid is involved in molting has been reported by Glazener and Jull …

The Changes in Egg Quality Resulting from Force Molting White Leghorn Yearling Hens

THE practice of forcing White Leghorn yearling hens to molt during the late spring or early Summer, for the purpose of securing greater production of higher quality eggs during the period of peak fall egg prices, is quite widely followed by the commercial poultrymen of Washington. That the practice of force molting, as conducted by the poultrymen, can be successful is indicated by the increasing number of poultrymen each year who are following the procedure and are continuing to do so year after year.The poultrymen who have successfully force molted yearling hens have claimed that flocks which are force molted not only produced more eggs but also produced eggs of improved grades during the fall months, than do flocks which are permitted to lay and molt normally. The authors, who had been studying shell and albumen quality, were interested in these claims of improved egg grades following the forced .