Force-molted Hens Research Articles

Enrichment of Vitamins D3, K and Iron in Eggs of Laying Hens

An experiment was conducted to produce eggs enriched with vitamins D3, K and iron in eggs. Six hundred 97-wk-old ISA Brown force molted hens were allocated to completely randomized block arrangement of six dietary treatments: T1; control (C), T2; C+4,000 IU vitamin D3+2.5 mg vitamin K+100 ppm Fe, T3; C+8,000 IU vitamin D3+5.0 mg vitamin K+100 ppm Fe, T4; C+12,000 IU vitamin D3+7.5 mg vitamin K+100 ppm Fe, T5; C+16,000 IU vitamin D3+10.0 mg vitamin K+100 ppm Fe, T6; C+20,000 IU vitamin D3 +12.5 mg vitamin K+100 ppm Fe. Fe was supplemented with Fe-methionine. Each treatment consisted of five replicates of ten cages with two birds per cage. Egg production and egg weight were highest in T2 and incidence of soft and broken egg was highest in T6. Haugh unit was not different among treatments although it tended to be increased as dietary vitamins D3 and K increased. Eggshell strength was not different among treatment. Concentrations of vitamin D3 and K in egg yolk increased and plateaued approximately 20 days after feeding supplemented diets. The level of these vitamins peaked at 12,000 IU/kg vitamin D3 and 7.5 mg/kg vitamin K supplementation and then decreased at the higher than these supplementation levels. The peak concentrations of vitamin D3 and vitamin K were 4.6 times and 4.8 times greater than the control, respectively. Supplementary Fe also increased Fe content in egg yolk. It is concluded that vitamin D3 and K in eggs can be effectively enriched by proper supplementation time and level of these vitamins. (Asian- Aust. J. Anim. Sci. 2005. Vol 18, No. 2 : 226-229)

The relationship between meteorological changes and daily feed intake or shell strength of eggs of Leghorn hens

Feed intake and egg measurements were recorded daily over a 56-d period from Leghorn pullets and force-molted hens, with 36 of each age. Meteorological conditions during the experiment were obtained from a nearby weather station. Regression analyses indicated that the daily variation in flock parameters reported in other studies may be partly due to the flock's response to weather conditions outside the hen house. Key words: Poultry, meteorological conditions, correlations, flock parameters, feed intake, specific gravity, shell strength, temperature

Ovarian Steroid Production in Vitro During Gonadal Regression in the Turkey. II. Changes Induced by Forced Molting1

In the turkey, the onset of incubation behavior is associated with altered ovarian steroidogenesis, ovarian regression, decreased, LH secretion, and increased serum prolactin (Prl) levels. To clarify the relative contribution of circulating LH and Prl to the initiation of ovarian regression, laying hens were exposed for 0, 3, 7, or 14 days to a forced molting procedure (exposure to reduced day length of 6L:18D and removal of feed and water for the initial 3 days) that induces ovarian regression and decreased LH levels but does not increase Prl levels. On each of these days, hens were killed and granulosa and theca interna cells from the largest (F1) and fifth largest (F5) preovulatory follicles and total cells from the small white follicles (SWF) were incubated for 5 h in the presence or absence of ovine LH (oLH; 0-1,000 ng/ml). Force-molted hens exhibited diminished levels of circulating LH, Prl, progesterone (P), androgen (A), and estradiol (E) by Day 3 of treatment. Ovarian atresia began in F1 by the third day of treatment, and included F1 and F5 by the seventh day. No preovulatory follicles were present on the fourteenth day. With both F1 and F5 granulosa cells, production of P in the presence of oLH was initially enhanced (Day 3) and later absent (Day 7). In contrast, production of A by F5 theca interna cells in the presence of oLH was initially suppressed (Day 3) and then returned to pretreatment levels (Day 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Observations on Daily Variation in Feed Intake and Shell Strength of Eggs from White Leghorn Pullets and Force Molted Hens

Variation in feed intake, egg and shell weight, and five estimates of shell strength were measured over 14 days in one experiment and 56 days in another. Forty-eight force molted hens were used in the first experiment, and 36 pullets and 36 force-molted hens in the second. Shell thickness (STK), specific gravity, nondestructive deformation, quasistatic compression fracture strength (CFS) and specific strength (CFS/STK) were used to measure shell strength. In both experiments, birds from two strains were used; in the second, two rooms were used with the strains and age of bird balanced across rooms.Plots of the daily means and the ranges showed systematic variation from day to day with marked changes occurring within a few days. The differences among days were significant (P<.01 in most cases) for all variables measured in both experiments, except for egg weight in Experiment 1 (P>.05). Little evidence was found of a relationship between feed intake and shell quality. There were few significant interactions (P<.05) between strain, age, or room and day. These results show that research on egg shell strength should be planned so that systematic daily variation is not confounded with treatment comparisons.

Repeatability of Egg Shell Quality Measurements Within Individual Hens

Correlations of egg measurements between eggs laid by the same hen were examined using two experimental strains of White Leghorns, a control strain and a strain selected for high production and specific gravity. Eggs were collected for 56 days from 72 birds, that is, 18 pullets and 18 force-molted hens from each strain. At the beginning of the experiment, the pullets were 342 days of age and the force-molted hens 721 days of age. Egg variables measured were egg and shell weight, specific gravity, nondestructive deformation, quasi-static compression force to fracture, and shell thickness. Correlations between the same measurements on eggs laid 1 day apart were .89, .82, .67, .36, .50, and .54, respectively; these correlations decreased relatively little even for eggs laid 40 days apart. Correlations between mean measures on eggs gathered over successive 14-day periods were much higher – .94, .90, .84, .78, .85 and .81, respectively – reflecting the diminished influence of random variation within bird. Correlations within age-strain groups were smaller than the overall values, but the correlations seemed generally consistent from group to group. These results indicate that the measurements of shell strength from eggs of a bird provide a reliable indicator of the strength of future egg shells from that bird.

Ahemeral Light Cycles and Protein Levels for Older Laying Hens

Variations in light:dark ratios and timing schedules of 26- and 28-hr ahemeral cycles were examined for their effects on shell quality and egg weight. In two experiments utilizing 2578 White Leghorn Laying hens, 16-week long ahemeral treatments were instituted abruptly late in the pullet laying season and again following a forced-molt production cycle.Ahemeral light-dark cycles of 28-hr length resulted in significantly heavier shell and egg weights as compared to 26-hr ahemeral cycles or the control 24-hr cycle. Ahemeral 26-hr cycles did not significantly increase egg weight compared to the 24-hr controls but did increase shell weight. Varying total light in 28-hr cycles from 20 to 10 hr with the light given in either one continuous period or interrupted by two intermediate dark periods and as either 18 or 16 hr of continuous light in the 26-hr cycles did not result in significant differences in shell or egg weight compared to the other treatments of the same cycle length. Rate of lay was lower for the hens given only 10 hr of interrupted light in a 28-hr cycle but was not otherwise affected by light treatment.Dietary protein levels of 15% (as compared to 17%) and 14% (as compared to 16 and 18%) consistently reduced egg weights (P<.10 or <.05) and tended to improve shell quality.These experiments further demonstrated the effectiveness of 26- and 28-hr ahemeral light-dark cycles in increasing shell weight as a method of extending the economic laying period of either older pullets or force-molted hens without a sacrifice in the number of eggs produced.

Influence of Premolt Production on Postmolt Performance with Explanation for Improvement in Egg Production Due to Force Molting

Performance of force-molted hens as influenced by premolt production was determined in two experiments using 720 Babcock hens. Hens selected to be laying at a low (41%), average (59%), and high (75%) rate of production were divided into two groups. One half of the hens were force molted (FM) and the other half served as controls (CON). On completion of the fasting period, blood was collected for chemical analyses from 10 hens per group. These hens were then necropsied and weights of the ovary, oviduct, liver, and fat pad determined. During the last 4 weeks of the postmolt period, dietary calcium was increased from 3.5 to 4.5% in half of each group.Postmolt production was directly related to premolt production. The hens laying the highest rate premolt showed no improvement, whereas those laying at the lowest rate showed the greatest improvement. The FM hens exhibited a lower incidence of shell-less eggs than CON hens. Premolt production appeared to have little influence on postmolt egg weight, organ weights, and blood constituents. However, shell weight and egg specific gravity were significantly improved by force molting. Increasing dietary calcium had no significant influence on shell weight and specific gravity in FM hens in either experiment but significantly increased specific gravity and shell weight of CON hens during Experiment 2.It was concluded that most of the improvement in production in force-molted hens was caused by a reduction in shell-less eggs and not by an increase in ovulation. Also, only a portion of the improvement in shell quality could be explained by an increase in feed intake (calcium intake) after molting due to the increase in production. An improvement in calcium metabolism was postulated to be a major cause of improved shell quality.

Factors Affecting Broiler Breeder Performance: 4. The Interrelationship of Some Reproductive Traits

A series of experiments was conducted to determine the interrelationship of some reproductive traits in pullet and force-molted broiler breeder females. Correlation coefficients were obtained among fertility, hatch of fertile eggs, egg shell quality (specific gravity), hen-day production, and body weight. Body weight was negatively correlated with all traits except egg weight. Egg shell quality exhibited a consistently significant positive correlation with fertility. Eggs with specific gravities of <1.080 had lower fertility and hatch and higher early and late embryonic mortality than eggs with specific gravities >1.080. Additionally, duration of fertility was longer in hens producing eggs with higher specific gravities. Fertility was also positively correlated with hatch and hen-day production in pullets but not with force-molted hens. Hatch and hen-day production were found to consistently exhibit a positive correlation.

Forced Rest Induced by Molt or Low-Salt Diet and Subsequent Hen Performance

Four commercial strains of Single Comb White Leghorn hens were either force-molted by standard methods or force-rested by means of a low-salt diet (no added salt) at 66 weeks of age. After an 8-week molt/rest period, all hens were fed the same standard layer diet for an additional 28 weeks.During the resting period, egg production of the hens fed the low-salt diet declined gradually to a daily low of 13.0 percent after 38 days while the force-molted hens were completely out of production in 7 days.The low-salt treatment adversely affected postmolt hen-day and hen-house egg production, feed efficiency, egg shell thickness, and resulted in more broken eggs (P<.05) as compared to the force-molt treatment. Body weight gain, egg specific gravity, and egg weight were also depressed by the low-salt treatment, although not to a significant extent.The poorer postmolt performance of the hens fed the low-salt diet was believed related to a higher level of sodium in the diet (.13%) than had been calculated (.044%)

The Effects of Dietary Phosphorus, Vitamin D3, and 25-Hydroxy Vitamin D3 Levels on Feed Intake, Productive Performance, and Egg and Shell Quality in Two Strains of Force-Molted White Leghorns

A total of 576 force-molted hens were used to investigate the effect of dietary phosphorus level, and the source and level of vitamin D3 on egg production and shell quality. The experiment was a 2 × 2 × 2 × 3 factorial design with two strains of hens, two levels of available phosphorus (.34 and .60%), and two sources of D3 (25-hydroxy vitamin D3 and vitamin D3) at three levels (8, 16, 24 μg/kg); the diets were provided ad libitum for 84 days (from 646 to 730 days of age). Egg and shell quality measurements were taken on eggs laid over a 4-day period when the hens were 727 days of age. Dietary phosphorus level, and D3 source and level had no significant (P>.05) effect on 730-day body weight, feed intake and efficiency, egg production and yield, shell weight, percent shell, shell weight per unit surface area, Haugh units, blood spots, egg specific gravity, nondestructive deformation, compression fracture force, and shell thickness. There were significant differences among strains for the aforementioned variables except feed intake, egg weight, Haugh units, and blood spot incidence. Few interactions were found between the main effects. Results indicate that no improvement in shell quality of eggs from force-molted hens was obtained by decreasing the level of phosphorus or substituting 25-hydroxy vitamin D3 for vitamin D3 in the diet.

Artificial Insemination of Individually Caged Broiler Breeders: 1. Reproductive Performance of Males in Relation to Age and Strain of Females

Studies were conducted to evaluate the reproductive capacity of male broiler breeders used for artificial insemination over an extended period and mated to females of six strains. Biweekly determinations were made of semen volume, semen concentration, and spermatozoal motility for each of the 47 males caged individually from their 39th to 63rd week of age. The percent fertility, duration of fertility, and percent hatchability were determined at five-week intervals (periods) using three young and three force-molted broiler female strains.With young female strains, the mean percent fertility for a 7-day collection of eggs following a single insemination (1 to 7 days) ranged from 95.7 to 81.1 over six consecutive periods. The mean duration of fertility (days) and the mean percent hatchability of fertile eggs was 13.3 and 13.0, and 92.5 and 84.9 respectively, for the first two periods. With force-molted hens, the mean percent fertility (1 to 7 days) ranged between 97.2 and 86.0 over the first three periods, and the mean duration of fertility and the mean percent hatchability was 13.2 and 12.8, and 91.5 and 84.1, respectively, for the first two periods. Fertility of eggs collected for 10 days following a single insemination was slightly but consistently lower than fertility over 7 days for both female groups.Significant differences among males and between periods existed for each semen trait. The effects of male, young female strain and period on fertility and duration of fertility were significant. Hatchability was significantly affected by period only. No male by female strain interaction existed for percent fertility or hatchability. A significant male by period interaction existed for percent fertility, semen volume and concentration. The results obtained are considered to support the feasibility of maintaining broiler breeders in cages and the use of artificial insemination (AI) to produce broiler hatching eggs.

Effects of Force-Molting by Conventional and Experimental Light Restriction Methods on Performance and Agonistic Behavior of Hens

We conducted two experiments to compare the effects of force-molting on performance and agonistic behavior of White Leghorn hens. Treatments in Experiment 1 were 1) stress period (no feed and 8 hr light/day for 10 days) followed by recovery period (ground corn and 8 hr light/day for 18 days) and 2) same as Treatment 1 except that ground corn was supplemented with the amino acids cystine, glycine, serine, and threonine. Experiment 2 consisted of two treatments: 1) same as Treatment 1 of Experiment 1 and 2) stress period (cracked corn and no light for 10 days) followed by recovery period (same as Treatment 1; Experiment 1). In both experiments the hens were given 14 hr light/day and were fed a 17% protein layer mash during the premolt and postmolt periods. Nonmolted hens served as controls in both experiments.Force-molted hens fed ground corn supplemented with amino acids during the recovery period did not have significantly better egg production, egg weight, or egg quality than hens fed ground corn only. Force-molting by total light restriction was generally not superior to a conventional method (feed and partial light restriction) of force-molting, although hens force-molted by total light restriction did produce significantly heavier eggs (P <.05) than hens force-molted by a conventional method (67.6 g vs. 65.5 g). Force-molted hens performed significantly more agonistic acts per 10-min observation during the 18-day recovery period than did hens not force-molted. Data suggest that the social inertia (peck-order stability) of a small flock can withstand the pressures of a force-molt.

The Effects of Level and Source of Ammonium Sulphate on Feed Intake, Egg Production, and Egg Quality in White Leghorn Pullets and Force Molted Hens

The effects of supplementing a laying hen diet with graded levels of ammonium sulphate (AS) (0, 10, 20, and 30 g AS/kg) were investigated in two experiments using individually caged Single Comb White Leghorn hens from two strains. In the first experiment, pullets were fed diets containing technical grade AS between 226 and 500 days of age while in the second, force molted hens were fed, between 590 and 677 days of age, the same levels of AS but from four sources: the technical, a feed, and two fertilizer preparations. With the pullets, there was no (P>.05) compensatory increase in the intake of the supplemented diets due to the dilution effect of AS, but with the force molted hens compensation occurred. Consequently, AS level had a linear effect (P<.01) on the intake of basal diet by the pullets but no effect (P>.05) on basal intake by the force molted hens. There was a significant linear relationship between AS level and limestone grit intake for the pullets. Ammonium sulphate level had no effect on kg feed/dozen eggs, egg production and yield, mortality, egg and shell weight, percent shell, specific gravity, blood spots, and 500- or 677-day body weight of the pullets and force molted hens, respectively. Level of AS had a significant effect on shell weight per unit surface area, Haugh units, and kg feed/kg egg in the second experiment. Ammonium sulphate source had no influence on 677-day body weight, feed intake, productive performance, mortality, and egg and shell quality. These results indicate that if the cost of AS is relatively low, it might be used as a practical means of restricting the voluntary feed intake of young hens without affecting productivity, liveability, and egg and shell quality.

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 …