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PubMed1995

The effect of four levels of ascorbic acid and two levels of calcium on eggshell quality of forced-molted White Leghorn hens.

The present experiment evaluated the effect of four levels of ascorbic acid (0, 100, 250, and 500 ppm) and two levels of calcium (3.0 and 3.5%) on the productivity and eggshell quality of molted Single Comb White Leghorn hens, housed four per 30.5 cm wide x 45.7 cm deep cage. The 4 x 2 factorial treatment combinations were randomly assigned to eight blocks of cages. Egg production increased (P < .06) an average of 5% for the levels of 250 and 500 ppm ascorbic acid. No differences were observed for feed consumption, egg weight, and shell thickness for the different levels of ascorbic acid or calcium in the diet. An increase (P < .01) was observed for specific gravity, as the levels of ascorbic acid increased. Increasing the level of calcium from 3.0 to 3.5% increased (P < .01) specific gravity from 1.073 to 1.075. Shell weight increased (P < .01) with the higher levels of ascorbic acid (250 and 500 ppm). No interactions were observed between the levels of ascorbic acid and calcium. Results suggest that supplementing ascorbic acid to molted laying hens can be beneficial to egg production and eggshell quality.

Animal Feed↗
PubMed2003

Recruitment density can determine adult morphology and fecundity in the barnacle, Semibalanus balanoides.

Although consequences of the settlement preference of larvae have been well documented, the consequence of these settlement choices on subsequent mortality, morphology and fecundity has been little studied. The aim of this study was to determine the relationship between recruit and adult density and to determine the effect of recruitment on adult morphology and egg tissue mass. This study follows 48,718 barnacles (Semibalanus balanoides) from recruitment at the end of the settling season to reproductively mature adults at a field site in the Clyde Sea (UK). Overall survivorship of the recruits to adulthood was 8.5%, although survivorship was up to 42% on low density settlement panels. In low density colonies (< 10 recruits cm-2), recruitment density was related to adult density (P < 0.001), whereas no relationship was found for higher density colonies. A shell morphology index measured at adulthood was related to recruitment density for low density recruited colonies (P < 0.001) but not high density colonies. Using ANCOVA, variations between the colonies in shell and egg tissue mass were not explained by mass of somatic tissue. However, egg mass was explained by recruitment density (P < 0.01). These results show that adult density is not a reliable indicator of the previous population density of the colony. Moreover, there are marked differences in population development between colonies with high and low recruit densities in terms of impact upon shell morphology and egg production. The dynamics that operate between recruits at the end of the settlement season and sexually mature adults to create the patterns elucidated in this paper, and other literature, remain unclear.

Animals↗
PubMed1978

Role of shell diffusion area in incubating eggs at simulated high altitude.

Embryonic development is inhibited when eggs are incubated at 9,100 m (0.3 atm) despite a normoxic environment. The problem apparently relates to respiratory gas exchange occurring by diffusion through gas-filled pores in the shell. Gaseous flux is therefore inversely proportional to ambient pressure and is affected by the physical characteristics of the ambient gas (Chapman-Enskog equation). Excess loss of H2O and CO2 occurs in eggs incubating at altitude and could be detrimental. Such increased loss should be correctable by decreasing diffusion area. This was tested by progressively increasing coverage of the shell with paraffin and incubating at simulated 0.3 ATA (225 Torr) in 100% O2. Uncoated eggs failed to hatch, but numbers of chicks increased with increased coverage. Maximum hatch was an extrapolated 90% of controls at 69% shell coverage. With further coverage, hatch size decreased. Egg weight loss, and estimate of H2O diffusion, was around three times controls in uncoated eggs but decreased linearly with paraffin coverage, reaching near normal at maximum hatch. Reduction of diffusion area to 0.3 normal at maximum hatch generally balanced the increased flux predicted for 0.3 ATA.

Adaptation, Physiological↗
PubMed1990

Morphological changes in the oocyte and its surrounding vestments during in vivo fertilization in the dasyurid marsupial Sminthopsis crassicaudata.

This light and transmission electron microscopical study shows that the first polar body is given off before ovulation and that part of its cell membrane and that of the surrounding oocyte have long microvilli at the time of its ejection. Several layers of cumulus cells initially surround the secondary oocyte and first polar body, but the ovulated oocytes in the oviducts in the process of being fertilized do not have cumulus cells around them. Partly expelled second polar bodies occur in the oviduct; they are elongated structures that lack organelles and have electron-dense nuclei. A small fertilization cone appears to form around the sperm tail at the time of sperm entry into the egg and an incorporation cone develops around the sperm head in the egg cytoplasm. In three fertilized eggs a small hole was seen in the zona, which was presumably formed by the spermatozoon during penetration. Cortical granules, present in ovarian oocytes, are not seen in fertilized tubal or uterine eggs; release of their contents probably reduces the chances of polyspermy, although at least one polyspermic fertilized egg was seen and several other fertilized eggs had spermatozoa within the zona pellucida. In the zygote the pronuclei come to lie close together, but there was no evidence of fusion. A "yolk mass," which becomes eccentric before ovulation, is extruded by the time the two-cell embryos are formed, but many vacuoles remain in the non-yolky pole of the egg. A shell membrane of variable thickness is present around all uterine eggs but its origin remains undetermined.

Animals↗
PubMed1976

Calcium balance in the quail (Coturnix coturnix japonica). 1, Influence of sex and diethylstilbestrol.

Young adult male and laying female quail, fed with a diet containing 2.64% Ca and 0.70% P, were used to study nutritive utilization, corporal calcium retention and endogenous excretion, calcemia, laying and properties of the egg (including the shell structure), mineralization of the femur bone, as well as the influence of diethylstilbestrol upon these parameters. The coefficient of nutritive utilization (C.N.U.) in the female was high and logically superior to that of the male, while the corporal retention was quite similar for both sexes. Most of the Ca absorbed (81.8%) and not excreted in urine, went to the egg and only 18.2% remained in the body. The diethylstilbestrol caused a big reduction of the C.N.U. in the female, but not in the male, parallel to an inhibition of laying, and an increase of corporal retention of used calcium. In both sexes the calcemia surprisingly increased, and the calcium level of the femur bone was higher, and even though the cortical osseous zone was slightly wider, the effect of treatment was noticeable, particularly in the medular tissue, which incremented in the female and appeared in the male. When quail were fed a calcium-restricted diet, the endogenous excretion of this mineral was small in the case of the female and significantly smaller in the male. This situation suppressed egg laying and resulted in a clearly decreased bone mineralization. The ingestion of diethylstilbestrol before feeding a diet poor in calcium provoked an increase of the endogenous excretion of calcium in both female and male quail.

Animals↗
PubMed1995

Effects of presence of an egg and calcium deposition in the shell gland on levels of messenger ribonucleic acid of CaBP-D28K and of vitamin D3 receptor in the shell gland of the laying hen.

Levels of calbindin-D28K (CaBP-D28K) mRNA and vitamin D3, 1 alpha, 25(OH)2D3, receptor (VDR) mRNA in the intestine and shell gland were measured in the laying hen during the ovulatory cycle by Northern and slot blot analyses. In addition, effects of presence of an egg and calcium deposition in the shell gland on the levels of both mRNAs were studied either by delay in oviposition (retaining the egg in the shell gland beyond the expected time of oviposition) or premature oviposition (emptying the shell gland and arrest of calcium deposition). During the ovulatory cycle mRNA levels of CaBP-D28K and of VDR remained relatively constant in the intestine. In contrast, both mRNA levels of the shell gland were low when there was an egg in the infundibulum, magnum, and isthmus, but significantly increased when there was an egg in the shell gland during shell formation. The im injection of indomethacin 3 hr before expected ovulation delayed oviposition but increased neither shell thickness nor mRNA levels of CaBP-D28K and of VDR. On the other hand, premature oviposition reduced mRNA levels of both CaBP-D28K and VDR in the shell gland. These results suggest that the presence of an egg and calcium deposition in the shell gland may be a stimulatory factor for synthesis and accumulation of CaBP-D28K mRNA and VDR mRNA in association with calcification.

Animals↗
PubMed2006

Effects of strontium on bone strength, density, volume, and microarchitecture in laying hens.

UNLABELLED: Strontium has been reported to have beneficial effects on bone. Treatment of laying hens, which are susceptible to osteoporosis and bone fracture, with strontium increased DXA measurements of BMD and BMC and microCT measurements of bone volume and microarchitecture and improved the mechanical performance of whole bone, but had no effect on the estimated material properties of the bone tissue. INTRODUCTION: Strontium (Sr) has been reported to dissociate bone remodeling and have positive influences on bone formation. We supplemented the diet of laying hens, which are susceptible to osteoporosis and bone fracture, with Sr to study the capacity of the element to improve bone mechanical integrity and resistance to fracture. MATERIALS AND METHODS: Increasing dosages of Sr (0, 3000, 4500, and 6000 ppm) were fed to 196 13-week-old pullets for 11 months. BMD and BMC, as measured by conventional and DXA methods, microarchitectural parameters derived from microCT, and structural and material properties as determined by three-point bending test, were studied. Calcium (Ca), phosphorus (P), and Sr levels in plasma and bone, as well as egg output, shell quality, and composition, were assessed. RESULTS: Sr concentrations in plasma and bone increased in a dose-dependent manner without affecting Ca and P. Treatment with Sr increased BMD and BMC as measured by DXA, increased cortical and medullary bone volume, trabecular thickness, number, and surface, and improved whole bone ultimate load, but had no effect on the estimated material properties of diaphyseal bone. Sr also increased the ash content of eggshells and did not affect egg output and shell quality. CONCLUSIONS: Sr supplementation induced large positive effects on bone density, volume, and microarchitecture as measured by radiographic methods. Sr treatment also improved the structural strength of diaphyseal bone but had no effect on the estimated material properties of the bone tissue.

Animals↗
PubMedDate not supplied

Physical effects of shock waves on the kidney. A commentary based on several experiments.

An egg can be an excellent experimental model for it provides us with accurate information on the effects of shock waves on biological structures of acoustic impedance identical to that of human cells and interfaces of small width. The authors divided the experiments into two groups. The one in which the shock wave was focused on the whole egg--its shell is almost transparent to shock waves--showed that hyperpressures on thin interfaces have hardly any destructive effect, whereas in the other in which the egg was used without the shell and the shock wave was directed to the yolk, yolk fragments were thrown into the surrounding water, indicating that destructive effects are caused by the cavitation effect. The authors suggest some penetration ranges of shock waves on the kidney which they consider to be the least harmful.

Eggs↗
PubMed2000

Lack of response of laying hens to relative humidity at high ambient temperature.

1. The effects of relative humidity (rh=40% to 70%) at high ambient temperature (Ta) on the performance of laying hens at different ages (8 to 10 months, Trial 1; and 16 to 18 months, Trial 2) was evaluated. Laying hens were exposed to 25 degrees C (control) for 3 weeks and thereafter acclimated for 1 week to 35 degrees C and 4 different rh. 2. Body weight declined significantly in young and older hens exposed to 60% or 70% and 70% rh, respectively: Food intake declined with increasing Ta, except in the case of older hens exposed to 60% rh, for which it remained relatively constant. Water consumption, however, increased with increasing Ta but the increase was significant in young hens exposed to 70% rh only. 3. Egg production was not affected by the changes in Ta. However, a decrease in egg production was observed in older hens exposed to 60% rh. 4. Egg weight (EW), shell weight (SW) and shell thickness (ST) were significantly reduced by exposure to elevated Ta, whereas % breakage significantly increased. In young hens, a response to rh was exhibited in ST which was significantly higher in hens exposed to the low rh (40% to 45%) than in those exposed to the highest rh (70% to 75%). 5. It can be concluded that Ta is the main environmental factor affecting young and older laying hens while the effect of rh is minor.

Age Factors↗
PubMed1975

Effects of short term phosphorus deprivation on laying hens.

An experiment was conducted to determine the effects on laying hens of ingestion of a phosphorus deficient diet for 6, 9, or 21 days. Four experimental groups consisting of 3 replicates of 5 Leghorn pullets averaging 90 percent egg production were maintained in individual cages. A diet containing corn, soy, and meat and bone meal was formulated to contain 0.39 percent total P on a 90 percent dry matter basis (LP). A normal P diet (NP), 0.64 percent total P, was obtained by supplementation with an inorganic P source. Group 1 (Control) was fed the NP diet for 21 days. Groups 2, 3 and 4 were fed the LP diet for 6, 9, and 21 days respectively. Groups 2 and 3 resumed consumption of NP diet after 6 and 9 days. Individual egg production and egg weight were recorded daily. Individual hen determinations of serum P, g. shell/cm.2 surface area, and feed consumption by replicate were made at 3 or 4 day intervals. The serum P of Group 1 averaged 5.01 +/- 0.31 mg./100 ml. over the 21 days. Serum P was significantly reduced after 3 days of consuming the LP diet. Serum phosphorus of Groups 2,3, and 4 were 2.95 +/- 0.18, 3.03 +/- 0.24, 3.13 +/- 0.32 mg./100 ml. respectively after 6, 9, and 21 days of consuming the LP diet. Serum P returned to control levels within 4 days after resumption of the NP diet by Groups 2 and 3. There were no differences in feed consumption, egg production nor any detrimental effects on egg weight or shell calcification despite the low serum P. Body weight gain of the hens fed the phosphorus deficient diet for 21 days was significantly reduced. At the end of the experiment femur density was determined; the hens which had consumed the phosphorus deficient diet for 21 days had reduced femur density (osteoporous) compared to the control group or the hens fed the phosphorus deficient diet for only 9 days. It is concluded that pullets in 90 percent production can tolerate this low P diet for at least 9 days without apparent detrimental effects.

Animal Feed↗
PubMed1978

Shell gland oxygen consumption in hens producing eggs of low or high specific gravity.

Oxygen consumption of shell gland lumenal tissue was found to be higher in hens producing eggs of high specific gravity (greater than or equal to 1.080) when compared to tissue from hens producing eggs of low specific gravity (less than or equal to 1.075). Shell gland lumenal tissue oxygen consumption was also greater when an egg was in the shell gland as compared to hens with an egg in the magnum (9.8 and 8.0 microliter O2/hr/mg tissue respectively).

Animals↗
PubMed1989

The structure of the shell and polar plugs of the egg of the whipworm, Trichuris trichiura (Nematoda: Trichuridae) from the Samango monkey (Cercopithecus albogularis).

The structure of the shell of the egg of Trichuris trichiura was examined using light microscopy as well as scanning and transmission electron microscopy. The results confirmed its three-layered structure and provided evidence that the cores of the polar plugs, which could be seen to be extensions of the shell's middle layer, could be lost en bloc, either mechanically or chemically, and in this way probably provided an exit for the first stage larva at hatching.

Animals↗
PubMed2003

Effects of some egg characteristics on the mass loss and hatchability of ostrich (Struthio camelus) eggs.

1. This study was conducted to examine some egg characteristics and determine the effects of eggshell thickness and eggshell porosity on water loss and hatchability of eggs in ostriches. 2. Shell thickness did not correlate significantly with hatchability. However, eggs of low shell thickness lost more mass (13.03%) than those with intermediate (11.22%) and high (10.36%) shell thickness. Mass loss during incubation was higher in hatched (11.98%) than unhatched eggs (11.09%). Shell thickness was negatively correlated to egg mass loss (r = -0.65). 3. The pore density was correlated with hatchability. Hatchability was 50% lower in eggs with low pore densities (40.93%) than with high densities (80.94%). Pore density was positively correlated with egg mass loss (r = 0.63). Incubation mass losses of hatched and unhatched eggs were not significantly different. 4. Mean eggshell water vapour conductance (G) value and shell conductance constant (k) were 87.77 +/- 4.21 mg H2O/d/Torr and 2.44 respectively (n = 15). 5. Because of eggshell functional properties and resulting low egg mass loss hatchability is low when ostrich eggs are artificially incubated. The mass of eggs used in the experiment was relatively high and their eggshell water vapour conductance was low. As a result, egg incubation mass loss was lower than it should be. It is concluded that incubator humidity should be low (25%) to allow enough mass loss during incubation from the eggs.

Animals↗
PubMed1999

Measuring the mechanical stiffness of an eggshell using resonant frequency analysis.

1. A new method was introduced for the measurement of mechanical eggshell characteristics based on the analysis of the vibration response of a chicken egg excited with a non-destructive impact. Four major topics were examined. 2. The 3 dimensional vibration pattern of an intact chicken egg was described for the spherical vibration with the lowest resonant frequency. 3. The resonant frequency of this basic vibration mode and the total egg mass were used to calculate a dynamic stiffness value of the eggshell based on a mathematical mass-spring model. 4. A correlation analysis between this dynamic stiffness value and several common egg and eggshell variable was calculated. Pearson correlation coefficients between the dynamic stiffness and static stiffness, eggshell thickness at the equator, eggshell width and shape index were all significantly different from zero and were 0.71, 0.60, 0.43 and 0.51, respectively. 5. Graphical analysis of the static vs. the dynamic eggshell stiffness indicated that eggs with thick shells (>360 microm) had a higher static stiffness value than the dynamic stiffness measurement, whereas the static stiffness of eggs with thin shells (>300 microm) was lower than the dynamic stiffness. 6. The new vibration test method is a promising alternative for evaluating mechanical eggshell properties because of its non-destructive nature and brief measuring time.

Animals↗
PubMed1982

Organ growth in hyperoxic and hypoxic chick embryos.

Chick embryos and their organs were weighed in order to compare retarded growth with accelerated growth. Growth was quickened by incubating eggs in 60% O2/40% N2 and slowed by covering part of the shell of eggs incubated in air. A control group was incubated in air without any covering. At two-day intervals from the twelfth to the eighteenth days inclusive, eggs were opened and the embryos dissected and weighed. An organ was 'spared' if it differed from its control weight proportionately less than did the whole embryo. Covered eggs were opened only on the eighteenth day and showed sparing of brain and heart and hepatic stunting in excess of body stunting. Hyperoxic eggs spared brain and liver during the period in question, but the heart grew proportionately more than the other tissues between days 16 and 18. These data show that the availability of oxygen alters the rate of embryonic growth, and induces differential growth among individual organs.

Animals↗
PubMed1989

Effects of lighting program during the growing period and dietary fat during the laying period on broiler breeder performance.

In two experiments, broiler breeders were grown in either of two lighting regimens, fed diets without added fat, and then fed diets with or without 5% added poultry fat during the subsequent laying period. In Experiment 1 half the birds were subjected to decreasing daylength using daylight (800 lx) and half were subjected to 9 h of incandescent light (20 lx) to 20 wk of age. In Experiment 2 the lighting regimen was either an 8-h photoperiod supplied by daylight (800 lx) or an 8-h photoperiod supplied by incandescent light (20 lx) to 20 wk of age. Added dietary fat produced significantly higher egg weight (Experiments 1 and 2), egg production (Experiment 2), and significantly lower fertility and hatchability of fertile eggs (Experiments 1 and 2). Short photoperiods (8 or 9 h) provided by incandescent light produced significantly higher fertility (Experiments 1 and 2) and hatchability of fertile eggs (Experiment 2), and significantly lower egg specific gravity, shell percentage (Experiment 1), egg weight, and eggshell weight (Experiment 2). Effects on fertility may be related to higher female body weight during lay due to daylight rearing or added fat, or relative changes in light intensity at photostimulation.

Analysis of Variance↗