Shell gland adenosine triphosphatase in hens producing strong and weak egg shells

1. Two groups of 4 hens at the end of their first production cycle were classified as producers of strong egg shells (greater than 70 mg/cm2) and weak egg shells (less than 60 mg/cm2) on the basis of shell surface density. 2. Shell gland mucosa was homogenised and fractionated into nuclear, mitochondrial, microsomal and supernatant fractions, and ATPase activity determined. 3. ATPase activity in the total homogenate was significantly greater for hens producing strong shells (SES) than for hens producing weak shells (WES). 4. ATPase activities detected in the nuclear fraction, mitochondria and microsomes were significantly greater for SES than for WES birds.

Geographical distribution of contaminants and productivity measures of herring gulls in the Great Lakes: Lake Erie and connecting channels 1978/79

The distribution and size of colonies, residue levels of DDE, DDT, HCB, dieldrin, mirex and PCBs in eggs, productivity and eggshell thickness were determined for herring gulls at 14 sites in Lake Erie and connecting channels. The centre of distribution for breeding herring gulls was the Western Basin where approximately 90% of the 6200 nests in the study area were located. Seven of 22 colonies showed an average annual population increase of 48.3%. Most of the increase in breeding herring gulls on Lake Erie is directly associated with sites that have undergone habitat modification by man. Levels of PCBs and DDE ranged from 35 to 140 ppm (wet weight) and from 2.8 to 9.4 ppm, respectively; all other residues were less than 0.49 ppm. Most organochlorine residue levels were highest in eggs from colonies in or near the Niagara or Detroit Rivers. Mirex residues were greatest in the Niagara River and decreased significantly to the west. PCB residues were greatest in the Detroit River and decreased significantly to the east. The lowest levels generally came from colonies in the Sandusky Basin and near Pelee Island in western Lake Erie. Discriminant function analysis of six organochlorine contaminants correctly classified 90% or more of the eggs from up to four colonies in one or more years. Levels of PCBs and HCB appeared to have the greatest discriminating power. Herring gull productivity at all colonies (1-1.7 young gulls/pair) was normal and showed no significant geographical variation. Eggshell thickness was greatest in colonies in the Sandusky Basin and least in colonies in the Detroit River and extreme west end of the lake; mean eggshell thickness was 0.350 +/- 0.02 mm (6.7% thinning), which was weakly, but significantly correlated to DDE concentration. The variation in contaminants in herring gull eggs on a Basin basis (i.e., Western, Eastern, Sandusky, etc.) paralleled those known for sediments, water and fish. Thus, we suggest that in addition to its role as an indicator of lake-wide contamination of the Great Lakes, the herring gull, under some circumstances, may function as an indicator of "regional" contamination. This is an important distinction as it improves the geographical specificity of the herring gull as an indicator species on the Great Lakes, where it is a non-migratory species.

Modelling the relationships of egg weight, specific gravity, shell calcium and shell thickness

1. The relationships between egg weight, egg specific gravity, shell weight, shell calcium and shell thickness of 800 eggs from 8 treatments were expressed using mathematical models. 2. The equations describing the relationships were on the basis of any two independent variables predicting the remainder. 3. Of 10 possible models, 4 had high co-efficients of determination (R2 greater than 0.80) for each predicted dependent variable. 4. The two independent variables in each of these 4 models were, in turn, egg weight and specific gravity, egg weight and shell weight, egg weight and shell thickness, and specific gravity and shell weight. 5. The best model was that having egg weight and specific gravity as independent variables, with R2 values of 0.94, 0.88, and 0.85 for predicted shell weight, shell calcium, and shell thickness, respectively. Moreover, egg characteristics can be measured non-destructively by this model, whereas the other three require destruction of the egg.

The effect of chronic lead intoxication in mature chickens

In a study of chronic lead intoxication in mature chickens, blood lead levels were significantly lower in hens than in roosters receiving the same oral dose of lead. It was then shown that eggshells from lead-treated hens contained 6-12 times the lead concentration of eggshells from control hens. Similarly, the lead content of egg yolks from treated hens was significantly higher than yolks from controls. Lead-treated hens laid significantly more eggs during the period of observation of nearly 3 years because of the increased frequency of laying cycles, which was almost three times that of control hens. A further observation was histologic damage to the mature testes of the rooster.

Regulation of net intestinal calcium uptake in hens laying obligatory soft-shelled eggs

1. Individually caged laying hens had a loop of thread inserted into the shell gland. This resulted in the laying of soft shelled eggs. 2. A balance study was performed for a one week period before and after the operation. After the operation birds with threads consumed less calcium than before. Their requirements for calcium for eggshells decreased, resulting in increases in both calcium excreted and calcium retained. 3. Net calcium extraction in the digestive tract was measured in groups of birds with threads and intact controls, when shelling or not, by examining ratios of Ca to TiO2 in different gut segments. Observations were made during the period following premature oviposition in birds with threads, but within the normal shelling period of control birds. The period of study was at least two weeks after the operation. 4. Birds with threads absorbed less calcium than control birds up to the upper jejunum. 5. Control birds secreted calcium between the upper jejunum and colon, but birds with threads showed little change in absorption in this part of the digestive tract. 6. The increase in calcium absorption in intact birds was a response to the stimulus of shelling an egg or replacing calcium in medullary bone during a pause day, rather than of ovulation.

Characterization of electrolytes and protein content in isthmic and uterine flushings from hens laying shell-less versus hard-shell eggs

In Experiment 1, hens laying hard-shell (HS) eggs were sacrificed at each of eight stages of egg formation including oviposition (0 h) and 1, 4, 8, 12, 16, 20, and 24 h after oviposition. In Experiment 2, hens laying either shell-less (SL) or HS eggs were sacrificed at four stages of egg formation (oviposition, 4, 8, and 20 h after oviposition). The isthmus and uterus were flushed with 6 and 10 mL of cold .85% NaCl, respectively, and electrolyte contents were determined. Total flushing contents of calcium, potassium, and magnesium were higher (P less than or equal to .01) in uterine than in isthmic flushings (Experiment 1). In every case, an interaction (P less than or equal to .01) between time of collection and organ (isthmus and uterus) was found, indicating that patterns of change in flushing content of each electrolyte differed in the two organs over time in birds laying HS eggs. In Experiment 2, total recoverable calcium, magnesium, potassium, and total protein were higher in uterine than isthmic flushings (P less than .01). Interactions between time of collection (0, 4, 8, and 20 h) and treatment group (SL or HS) were observed for all electrolytes measured in uterine flushings. Results suggest that calcium, required for shell calcification, does not appear in the isthmic or uterine lumen or both at an appropriate time in SL hens. Thus, production of SL eggs may be related to mechanisms regulating patterns of change or ratios of electrolytes (calcium, magnesium, potassium) or both in the isthmus or uterus of the laying hen.

Interaction of dietary calcium and chloride and the influence of monovalent minerals on eggshell quality

Two experiments were conducted to determine the influence of dietary sodium and chloride on eggshell quality of leghorn hens. In the first, hens were fed for 4 wk diets containing three levels of calcium (2.0, 2.8, and 3.5%) and two levels of chloride (.25 and .86%) in a factorial arrangement of treatments involving four replicates of five hens/treatment. Neither chloride nor calcium significantly affected hen-day egg production or egg weight (P greater than .05); however, chloride decreased feed consumption and calcium increased body weight gain (P less than .05). Interactions of calcium and chloride were significant for eggshell strength (P less than .06) and eggshell thickness (P less than .05). Chloride decreased these measures of eggshell quality only for hens receiving 2.0% calcium, and calcium improved both measures only for hens receiving .86% chloride. Chloride decreased blood bicarbonate concentration and base excess (P less than .05), but did not affect blood pH and pCO2 (P greater than .05). The effect of dietary sodium and chloride on eggshells of hens receiving 2.0% dietary calcium was determined in a second experiment. Seven diets ranging from .18% sodium and .94% chloride to .76% sodium and .24% chloride were provided for 4 wk to five replicates of five hens/treatment. Dietary sodium and chloride levels did not affect hen-day egg production or egg weight (P greater than .05). Increasing the proportions of sodium relative to chloride decreased food intake but increased eggshell strength and thickness (P less than .01) and increased blood pH (P less than .05), bicarbonate concentration (P less than .01), and base excess (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Further studies of effects of sodium aluminosilicate on egg shell quality

Five experiments were conducted using 36 dietary treatments to compare chloride salts and HCl as chemical sources of Cl for the adjustment of dietary Cl when using sodium aluminosilicate (SAS), to compare SAS to natural zeolites (clinoptilolite and mordenite), and to determine the appropriate level of dietary SAS for optimum egg specific gravity. The methods of Na and Cl correction used in the various treatments included altering the levels of NaCl, calcium chloride (CaCl2), potassium chloride (KCl), magnesium chloride (MgCl2), iron chloride (FeCl3), or hydrochloric acid (HCl). Experimental diets were fed for 6 to 8 wk. Results of all experiments (except Experiment 2) indicated that the addition of SAS to layer diets improved egg specific gravity and that correction for Na by removal of NaCl and the addition of HCl was not necessary for SAS to be effective. No beneficial effects of dietary SAS on egg specific gravity were observed when Na and Cl corrections were made using CaCl2, KCl, MgCl2, or FeCl3. The feeding of SAS has no influence on egg production in Experiments 1 and 3 but significantly improved egg production in Experiment 4, when it was added to diets containing 2.75% Ca. An adverse effect on production of feeding SAS was observed, especially at the higher levels of SAS in Experiments 2 and 5. In general, SAS tended to reduce feed consumption, with no effect on egg weight. It was concluded that .75% SAS will improve egg specific gravity approximately 1 to 3 units and that correction for Na was not necessary for SAS to be effective.

Levels of calcium and soluble collagen in turkey egg shell membranes

1. This experiment examined the effect of weeks in egg production and type of housing confinement of turkey hens on calcium and soluble collagen levels in egg shell membranes; and discussion was given to their apparent relationship to gas exchange in turkey eggs. 2. The high level of acid-soluble collagen in inner and outer egg shell membranes of aging caged hens compared with the same aged floor-penned hens may have a relationship with the low hatchability generally recognized in caged hens. 3. The levels of calcium found in the outer shell membrane are low and appeared to decrease with the age of the hen. 4. There were no differences over time in levels of total collagen and neutral salt-soluble collagen (newly formed collagen) found in egg shell membranes of turkey hens confined in cages or floor pens. 5. It is suggested that the acid-soluble collagen levels found in inner shell membranes may have a relationship in limiting respiratory gas exchange during latter incubation time, and thus limit embryo survival.

Effects of avian infectious bronchitis virus (Arkansas strain) on vaccinated laying chickens

Twenty-four-week-old white leghorn layers were inoculated subcutaneously with a killed Newcastle-infectious bronchitis (Massachusetts type) virus (MIBV) vaccine. The birds were challenged 194 days later intraocularly with Arkansas strain of infectious bronchitis virus (AIBV). The challenged hens laid significantly (P less than 0.005) fewer eggs than the unchallenged layers, and the eggs laid by the challenged groups weighed significantly less (P less than 0.001) than those laid by the unchallenged groups. Further, the internal quality (Haugh units) and shell quality of eggs laid by the challenged hens were significantly (P less than 0.005) inferior to the quality of eggs from unchallenged hens, and the challenged hens laid more soft-shelled, misshapen, and small-sized eggs than the unchallenged hens. The Arkansas serum hemagglutination-inhibition (AIBV-HI) titers of challenged birds increased continuously through 29 days post-challenge. The MIBV hemagglutination-inhibition (MIBV-HI) titers of killed-MIBV-vaccinated birds decreased during the same period. The study indicates that killed MIBV vaccine offered no protection to birds exposed to AIBV. The same vaccine was quite effective against a homologous (MIBV) virus challenge.

Laser-Raman and infrared spectroscopic studies of protein conformation in the eggshell of the fish Salmo gairdneri

Laser-Raman and infrared spectroscopic studies reveal abundant beta-pleated sheet conformation in the eggshell proteins of the fish Salmo gairdneri. This secondary structure is the underlying molecular conformation, dictating the formation of the helicoidal architecture of the eggshell. Disulphide bonds crosslink the eggshell proteins of the fertilized eggs and are apparently found in g-g-g (gauche-gauche-gauche), g-g-t (gauche-gauche-trans) and t-g-t (trans-gauche-trans) conformation. There is no evidence for the existence of free sulphydryls. The tyrosines appear to act as hydrogen-bond acceptors, whereas the aromatic residues phenylalanine and tryptophan are also eggshell protein constituents.

Methyl mercury decreases the eggshell thickness and inhibits the Ca2+ uptake in a homogenate of the eggshell gland mucosa and its subcellular fractions from the domestic fowl

In the domestic fowl 20 mg of methyl mercuric chloride (MeHg) in a single oral dose given a day before egg-laying reduced the eggshell index by 35% and decreased the Ca content of the eggshell by 31% compared with those in the eggs laid on the previous days. The plasma concentration of Ca was reduced by MeHg by 50% in comparison with controls. The Ca concentration in the shell gland mucosa was not decreased by MeHg in relation to the control value. The rate of ATP-dependent Ca2+ binding by the homogenate of the mucosa was reduced by 33% by MeHg in relation to the control rate. The activity of Ca2+-Mg2+-ATPase was not changed.

Effects of vitamin D deficiency in the chicken embryo

Vitamin D-deficient chicken embryos were obtained by feeding laying hens a diet in which 5 micrograms 1,25(OH)2D3/kg feed were substituted for the vitamin D3 supplement in the control diet. Hatchability, total Ca and inorganic P concentration in blood, and tibial ash/dry weight ratio were determined in the vitamin D-deficient embryos and in embryos obtained from hens fed the control diet supplemented with 1100 IU vitamin D3/kg feed. After 5 weeks on the substituted diet the hens laid eggs that showed decreased hatchability in spite of excellent shell quality. All determinations in blood and bones were made on embryos of eggs laid after 6-12 weeks on the diets. On the 17th day of incubation the embryos derived from hens fed the substituted diet showed significant hypocalcemia and hyperphosphatemia and a low tibial ash/dry weight ratio. Injection of 1,25(OH)2D3 3 days before killing corrected the hypocalcemia of the deficient embryos. Those chicks that managed to hatch had normal levels of calcium and inorganic phosphate 1 day after hatching. These findings support previous suggestions by us and other authors that vitamin D metabolites are required by the embryo in order to mobilize calcium from the shell, and decreased hatchability in vitamin D-deficient embryos is related to a defect in calcium mobilization from the shell. While in previous studies a decrease in hatchability was the only parameter used to judge D deficiency of the embryos in our present studies, the deficiency is confirmed by demonstrating a deficit in mineral metabolism which is a more specific sign of D deficiency.

Effect of lindane on eggshell characteristics and calcium level in the domestic duck

Adult laying domestic ducks (Anas platyrhynchos domesticus) were forced fed lindane (gamma-hexachlorocyclohexane) 20 mg/kg body weight daily, thrice/week and twice/week for 8 weeks. Significant shell thinning (18-21%) was observed in ducks with daily and thrice/week lindane feeding. SEM studies of thinned eggshells revealed reduced and tightly clustered mammillae with apparent decrease in intermammillary spaces and signs of inhibition of calcite formation. Such structural changes of thinned shells were associated with a significant reduction in the level of calcium both of the plasma and of shell gland of the ducks. Simultaneously, density of the pore in the shell and pore area/cm2 of the shell in these birds were drastically reduced, presumably because of total absence of 'large' pores in such shells. Such porosity change is suggestive of reduced conductivity of eggshell implying impaired hatching success. Diethyl stilboestrol post-treatment neutralized all the adverse effects of lindane on duck eggshell, indicating induced estrogen deficiency in such birds by lindane.

The effect of variation of calcium intake on production performance and shell quality

Two experiments were conducted to determine the effects of moderate variation of calcium intake on production performance and shell quality. In Experiment 1, birds were fed diets containing 1.5 and 5.5% calcium, respectively, in the first and second 3-day period of 10 6-day cycles. In Experiment 2, calcium concentrations alternated between 2 and 5%. In both experiments, control groups were fed a diet containing 3.5% calcium for the duration of the experiment (60 days). Birds were 28 weeks old at the beginning of Experiment 1 and 50 weeks old at the beginning of Experiment 2. Overall egg production, egg weight, egg mass, feed consumption, feed conversion, and body weight gain were consistently lower for the birds of the alternating groups than the birds of the control groups in both experiments. Shell quality as measured by shell thickness, breaking strength, specific gravity, and percent shell in most cases was significantly reduced within 24 hr of feeding the low calcium diets and improved to normal within 24 hr of feeding the high calcium diets in both experiments. These experiments suggest that calcium variation of the extent used in these experiments reduces optimum performance; shell quality is reduced within 24 hr of feeding a low calcium diet.

Campylobacter jejuni in broilers: the role of vertical transmission

The role of broiler eggs in the transmission of Campylobacter jejuni to broiler grow-out flocks was investigated. Six breeder flocks supplying broiler eggs to hatcheries were examined for cloacal carriage of C. jejuni. Of 240 birds tested, 178 (74%) were C. jejuni-positive. Eggs from these birds examined for C. jejuni penetration of the egg shell indicated that 185 of 187 were campylobacter-free. Eggs from breeder flocks of unknown C. jejuni status were also examined for C. jejuni shell penetration. C. jejuni was not isolated from 142 eggs examined. A further 193 hatchery eggs incubated and hatched in the laboratory were campylobacter-free. Six farms containing the progeny of C. jejuni-positive breeder flocks were monitored. Eight hundred and forty birds from 14 flocks in these grow-out farms were campylobacter-free during their 6-week grow-out period. Experimental egg-penetration studies indicated that C. jejuni transmission via the egg is not easily effected. Of 257 eggs surface-challenged with C. jejuni, 162 hatched; all were campylobacter-free. Of 167 eggs injected with C. jejuni, 12 hatched; 2 of these were colonized with C. jejuni. Our data do not support a role for vertical transmission of C. jejuni in commercial broiler production.

Effect of short-term feed deprivation on shell quality in laying hens

Hens with feed withheld for 24 hr had poorer shell quality for the next 3 days. Hens with feed withheld for the first 8 hr (0400 to 1200 hr) of the 16-hr light cycle showed no decline in shell quality, but those with feed withheld the last 8 hr (1200 to 2000 hr) had poorer shell quality on the following day. When the period from 1200 to 2000 hr was divided into 2 periods (1200 to 1600 hr and 1600 to 2000 hr), feed restriction during the 1600 to 2000-hr period caused a decline in shell quality on the next day, but removal during the 1200 to 1600-hr period had no effect on shell quality. Shell quality was related to the feed intake of the hens, because about 34% of their feed intake was during the period 1600 to 2000 hr. Hens fed a low Ca diet (.7%) from 1200 to 2000 hr had poorer shell quality but not as poor as those with feed withheld. Feeding a high Ca diet (7.6%) from 0400 to 1200 hr prior to feed restriction from 1200 to 2000 hr, or giving oyster shell during the period of feed removal, improved shell quality, but not to the level of the full-fed birds. Daily feed restriction from 1200 to 2000 hr caused a reduction in shell quality for the first 4 days after which shell quality returned, but a slight decline in egg production was noted. These hens were able to consume approximately 70% of the feed consumed by the full-fed birds.

Influence of time of calcium intake on bone and dietary calcium utilization

Sixteen hens, 67 weeks old, having oviposition times at 0700 +/- .25 hr, were used in Experiment 1. Hens were randomly divided into two treatments and fed a .08% calcium diet following oviposition. For 5 days, at either 0800 (AM) or 1600 (PM) hours, hens received 3.65 g of calcium by intubation. On Day 1, the calcium source contained 25 microCi of calcium-45 (45Ca). Eggs and excreta were collected daily for 45Ca analysis. Experiment 2 was similar to Experiment 1 except that 34-week-old hens were used. Calcium-45 activity of the egg shell, excreta, serum, and total contents of the gastrointestinal (GI) tract was determined. Results of Experiments 1 and 2 indicated that hens receiving their daily supply of calcium in the PM deposited significantly more of that day's dietary calcium on the following day's egg than hens receiving calcium in the AM. Excreta from the AM-treated hens contained significantly more 45Ca than that from the PM-treated hens during the first 24 hr in both experiments. In Experiment 2, the quantity of 45Ca in serum and GI tract contents was significantly higher from hens in the PM treatment. It was concluded that hens utilized significantly more calcium for egg shell formation from PM consumption rather than AM consumption and, therefore, were less dependent on bone reserves when the calcium was consumed in the PM.

Influence of dietary ingredients on calcium utilization in the laying hen

Experiments were conducted to evaluate the benefit of calcium supplementation with or without other dietary ingredients on egg shell quality. A total of 250 Hyline hens, 44 weeks of age, were randomly divided among five treatments (Experiment 1). The dietary treatments were as follows: Treatment 1, controls (C) were fed a 3.5% calcium diet ad libitum; Treatment 2, hens were fed a .08% calcium diet (LC); Treatment 3, hens were intubated with limestone following 24-hr consumption of .08% calcium diet (LCI); Treatment 4, feed removed for 24 hr (NF); Treatment 5, feed removed for 24 hr and hens then intubated with limestone (NFI). All diets were restored to the control calcium level after 48 hr. Experiment 2 was identical to Experiment 1 except Dekalb XL hens, 50 weeks of age, were used. Eggs were collected daily for 5 days for egg specific gravity, egg weight, and shell weight determinations. Forty hens were sacrificed in Experiment 2 at 48 hr into the experiment to measure calcium distribution in the gastrointestinal (GI) tract and feces. Results indicated that hens fed the LCI treatment produced eggs with significantly higher specific gravity and heavier shells than hens given limestone with an empty GI tract. The calcium analysis of the GI tract revealed that much of the calcium supplement did not move beyond the gizzard in hens fed the NFI treatment. It was concluded that hens not only needed other nutrients for maximum utilization of dietary and skeletal calcium, but other nutrients or dry matter may also be needed to facilitate the passage of calcium from the gizzard.

Influence of dietary calcium on bone calcium utilization

In Experiment 1, 10 microCi 45Ca/day were administered to 125 hens for 10 days. Hens were then allocated to five treatments with calcium levels ranging from .08 to 3.75% of the diet. In Experiment 2, hens with morning oviposition times were randomly allocated to 11 treatments that were periods of time postoviposition ranging from 6 hr to 24 hr, in 2-hr increments (Experiment 2). At the end of each 2-hr period, eggs from 25 hens were removed from the uterus. The 18-, 20-, and 22-hr treatments were replicated three times. In Experiment 3, hens were fed either ad libitum or feed was withheld the last 5 or 6 hr before oviposition. In Experiment 4, hens were fed 10 microCi of 45Ca for 15 days to label skeletal calcium. Hens were divided into two groups and fed a .08 or 3.75% calcium diet for 2 days. On the second day, 25 hens fed the 3.75% calcium diet were intubated with 7 g of the same diet containing .5 g calcium at 1700, 2100, 0100, 0500, and 0700 hr. The measurements used were egg weight, shell weight, and 45Ca content of the egg shell. Results indicated a significant linear or quadratic regression of dietary calcium levels on 45Ca accumulation in eggshells and eggshell weight (Experiment 1). As the calcium level of the diet increased, eggshell weight increased and 45Ca recovery decreased. Utilization of skeletal calcium for shell formation ranged from 28 to 96%. In Experiment 2, the rate of shell calcification was not constant throughout the calcification process but varied significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Preovulatory concentrations of progesterone and estradiol in plasma and their relationships with eggshell quality in the laying hen

Laying hens were divided into high and low shell quality groups on the basis of egg specific gravity during the 5th, 7th, and 9th months of egg production. Concentrations of progesterone and estradiol-17 beta in the plasma were determined by radioimmunoassay in blood samples taken by cardiac puncture from hens at either 18, 21, or 24 hr postoviposition. Egg production and egg weight were not significantly different between shell quality groups; however, hens in the low shell quality group were heavier (P less than .05), had longer clutches (P less than .05), and lower egg specific gravity (P less than .0001) than hens in the high shell quality group. Egg production and clutch size declined (P less than .01) in both groups with increased age. Plasma estradiol and progesterone concentrations were not different between shell quality groups or among periods of production, though progesterone and estradiol concentrations were greater (P less than .005) at 21 hr postoviposition than at 18 or 24 hr. The correlation coefficient between plasma concentrations of estradiol and progesterone was significant. There was no significant association between the plasma concentrations of these hormones and egg shell quality. These data suggest that concentrations of estradiol and progesterone in plasma, during the 6 hr before ovulation, are not highly related to shell quality in the laying hen.

[Utilization of 15N marked urea by the laying hen. 2. Incorporation and metabolism of 15N for the synthesis of egg protein]

In an N-metabolism experiment 3 colostomized laying hybrids received 2870 mg 15N-excess (15N') per animal in 6 days in the form of urea with their conventional feed rations. During the 8-day experiment the 21 eggs laid were separated into eggshell, white of egg and yolk. Weight, N-content and 15N' were determined of the individual fractions of the eggs. On an average of the 21 eggs 4.6% of the heavy nitrogen was in the egg-shells, 50% in the white of egg and 45.5% in the yolk. 2.8%, 4.5% and 5.5% (hens 1...3) of the 15N' consumed were detected in the eggs. The maximum 15N'-output in the white of egg was reached on the 6th day, whereas 15N'-output in the yolk showed a nearly linear increase in the time of the experiment. The results show that labelled nitrogen from urea is incorporated into the egg to a lower degree than after the feeding of 15N-labelled proteins and that the development of its incorporation into the white of egg and the yolk differ from that after the feeding of 15N-labelled native proteins.

Effects of dietary fat level on laying hens fed various concentrations of calcium

The effects of supplementing laying hen diets with 0, 5, or 10% fat in the presence of 3.0, 3.6, or 4.2% dietary calcium was investigated using laying hens over a 7-week period. There was no significant effect of the fat or calcium treatments on laying hen performance as judged by feed intake, weight gain, egg production, egg weight, and egg shell deformation. Although there was an increase in fat retention with an increase in dietary fat level (P less than .01), a larger proportion (P less than .05) of unabsorbed fat was present as soap in the excreta of birds on these diets relative to those fed the control diet. There was evidence to indicate that most of the soap observed in the excreta of laying hens was formed in postabsorptive areas of the gut, thereby explaining why the detrimental effects of soap formation were not seen in the laying hen. Increasing the dietary calcium level reduced both percentage calcium (P less than .01) and magnesium (P less than .05) retention. There were no significant effects of the treatments on nitrogen and phosphorus retention. There were also no significant effects of the treatments on shell ash, shell calcium, magnesium, and phosphorus content. Increasing the dietary calcium level increased bone ash (P less than .05) while reducing bone magnesium content (P less than .05). There were no significant effects of the fat and calcium treatments on bone calcium and phosphorus content.

Shell quality as influenced by zeolite with high ion-exchange capability

Sixteen dietary treatments applied to a total of 960 hens were used to determine the influence of zeolite A on shell quality and egg size. In Experiment 1, sodium zeolite A (SZA) was fed at three levels (0, .75, and 1.50%) in diets containing 4.0 and 2.75% calcium (Ca) for 8 weeks to old hens. In Experiment 2, the same levels of SZA were fed in diets containing two total sulfur amino acid levels (TSAA, .61 and .51%) to young hens for 12 weeks. Calcium zeolite A (CZA) was also fed at .68% in Experiment 1 in the 4.0% Ca diets and in Experiment 2 in the .51 and .61% TSAA diets. These diets were adjusted for sodium (Na) and chloride (Cl). SZA (.75% unadjusted for Na and Cl) was fed to old hens receiving the 2.75% Ca diet in Experiment 1. All diets were isocaloric and isonitrogenous within diets having the same Ca or TSAA level within an experiment. Response criteria were egg production, feed consumption, egg specific gravity, serum Ca, and body weight. A significant linear response in egg specific gravity occurred within 2 or 3 weeks, when diets supplemented with SZA were fed to old (Experiment 1) and young (Experiment 2) hens. Average Ca intake for control hens (Experiment 1) fed the 2.75 and 4.0% Ca diets was 2.93 and 4.54 g, respectively. Average Ca intake for control hens (Experiment 2) fed the .51 and .61% TSAA diet was 4.38 and 4.00 g, respectively. The CAZ (Experiments 1 and 2) and SZA (unadjusted for Na and Cl, Experiment 1) also gave significant increases in egg specific gravity. Zeolite A had little or no influence on egg weight, feed consumption, or egg production in Experiments 1 or 2. When Na and Cl were not adjusted in the SZA treatments (Experiment 1) a significant reduction in production occurred. It was concluded that zeolite A will significantly increase egg specific gravity and we hypothesize that the mechanism responsible for the significant improvement is related to the high ion-exchange capability of zeolite A.

Magnesium, calcium, and phosphorus content of shells from hatching and nonhatching turkey eggs

Shells of hatching and nonhatching Large White turkey eggs were examined for magnesium, calcium, and phosphorus content. Eggshells containing embryos that hatched contained significantly (P less than .05) more magnesium than shells from nonhatching eggs. No differences were seen in their calcium content. Eggshells from pipped eggs contained significantly (P less than .05) more phosphorus than shells from eggs that were not pipped or those that hatched. Calcium and magnesium in turkey eggshells declined as time in lay increased. Injections of exogenous magnesium both at setting and transfer significantly (P less than .05) depressed hatchability, whereas exogenous calcium injected at transfer significantly (P less than .05) improved hatchability. Injections of exogenous calcium at the time of setting significantly (P less than .05) depressed hatchability. It was concluded that the mineral content of turkey eggshells may influence embryo physiology and hatchability.

Collagen in the egg shell membranes of the hen

Collagen-like proteins have been found in the egg shell membranes of the hen. Materials similar to types I and V collagens were detected in each of the two layers of this membrane, the thick outer membrane and the thin inner membrane. Collagen was extracted by acid-pepsin digestion and isolated by differential salt precipitation. Identification of type-specific collagen-like material was established by coelectrophoresis on SDS-polyacrylamide gels using known collagen standards. These bands were susceptible to digestion by bacterial collagenase. From differential staining of the gels it was estimated that the ratio of collagen types I:V was approximately 100:1. Further confirmation of these biochemical results was obtained with immunofluorescence microscopy using type-specific antisera against chicken types I and V collagen with the indirect sandwich technique. Both the inner and outer shell membranes contained the two types of collagen. Within each membrane, the large, coarse 2.5-micron fibers contained predominantly type I collagen-like material, while type V collagen was mainly associated with the delicate narrower fibers of approximately 0.6-micron diameter. These tended to be concentrated in the inner membrane. At the electron microscopic level, both types of fibers were coated with glycoproteins that stained positively with ruthenium red. The deposition of these collagen-like substances by the hen oviduct on to the surface of the developing egg is an additional example of interstitial-type collagen synthesis and secretion by epithelial rather than by mesenchymal cells.

Effects of vitamin D3 deficiency on adenosine triphosphatase activity of jejunums from white Leghorn hens

Supplemental vitamin D3 (D3) was removed from the diet given to an experimental group of White Leghorn hens, at 227 days of age, while a control group continued to receive a supplemental diet. By 14 days after D3 withdrawal, egg weight, egg specific gravity, shell weight, percent shell, shell thickness, and plasma calcium were lower (P less than .05) in the experimental compared to the control group. At 30 to 37 days after D3 withdrawal, experimental hens had less (P less than .05) jejunal adenosine triphosphatase (ATPase) activity than the control hens. The study indicated that lack of D3 supplementation in laying diets reduced jejunal ATPase activity as well as egg shell quality.

Comparison of the effect of DDE on the Ca metabolism of the eggshell gland and its subcellular fractions of the duck and the domestic fowl

In a strain of ducks sensitive to the eggshell-thinning effect of p-p'-DDE, administration of 40 mg kg of the compound in the food for 45 days reduced the eggshell index (EI) by 13% and the content of calcium in the fluid of the shell gland forming an eggshell by 36%, and raised the calcium content of the shell gland mucosa by 19%, compared with the control values. DDE inhibited the translocation (secretion) of calcium between the gland mucosa and the uterine cavity. The ATP-dependent binding of Ca2+ to the subcellular fractions of the gland mucosa was reduced in DDE-treated ducks. The Ca2+ binding to a microsomal subfraction (FI) rich in fragments of the plasma membrane was reduced by 16%, whereas that to a subfraction FIII which bound Ca2+ at a very high rate was reduced by 36%. The latter may contain calcium-secreting granules of the gland. In the mitochondrial fraction the Ca2+ binding was reduced by 35%. In the domestic fowl DDE did not lower EI or interfered with the translocation of calcium between the shell gland mucosa and uterine cavity. DDE administration increased the Ca2+ binding to FI by 26%; the binding to other subfractions was not changed significantly. DDE may interfere with the stimulus-secretion mechanism of the eggshell gland in ducks through its effect on Ca2+ binding.

Physiological profile of caged layers during one production year, molt, and postmolt: egg production, egg shell quality, liver, femur, and blood parameters

A longitudinal study of a flock of Single Comb White Leghorn pullets was initiated at 19 weeks of age (preproduction) and continued through a production year, a forced molt, and for 4 months of postmolt production. A representative sample of hens was obtained at 12-week intervals during the first year and at subsequent selected times. Liver lipid, femur weight, femur volume, femur density, egg weight, shell weight, percent shell, milligrams shell/square centimeter of shell surface area, serum calcium, serum phosphorus, and serum alkaline phosphatase were determined. Percent hen-day production peaked at 90% and then declined by .6 to .7% each week during the first production year. After molting, percent hen-day egg production peaked at 80% and declined .9% per week over the subsequent 20 weeks. Egg weight increased continually during the first production year. Shell weight was greatest immediately postmolt; thereafter it declined. Shell thickness was greatest at 31 weeks of age and declined throughout the first year. After molting, the shell thickness of 83-week-old hens was similar to values of hens about 37 weeks of age. Serum calcium and phosphorus of laying hens were influenced by age, feed intake and environmental temperature. The lowest values occurred during hot weather. Liver lipid was lowest in nonlaying hens (17 to 20%) and was approximately 42% of dry weight in laying hens. Femur density was greater in laying than nonlaying hens.

External incubation alters the composition of squamate eggshells

Eggshells of the skink, Eumeces fasciatus, and of the rough green snake, Opheodrys vernalis, contain 28-40% of total shell mass as calcium at oviposition. After incubation, both calcium concentration and content were reduced 17-41%. Protein accounted for 33-65% of shell mass in Eumeces and Opheodrys eggshells at oviposition. Reductions in protein concentration and content from 22-86% following incubation were observed. Comparing amino acid compositions of eggshells collected following oviposition with those collected from the same clutch after hatching reveals similarities among all eggshells except those of Eumeces from Michigan which lack desmosine and isodesmosine. Concentrations of desmosines in eggshells from Missouri and Michigan Eumeces appeared to decrease following incubation by 49.7% and 12.2%, respectively. Although neither the mechanisms involved in apparent losses of calcium and protein, nor the fate of the mobilized materials are known, possible pathways for mobilization of eggshell constituents are outlined and their pertinence to the physiology of squamate eggs and the evolution of viviparity in reptiles is suggested.

Effects of suppression of eggshell calcification and of 1,25(OH)2D3 on Mg2+, Ca2+ and Mg2+HCO-3 ATPase, alkaline phosphatase, carbonic anhydrase and CaBP levels--II. The laying hen intestine

Activity of a HCO-3 stimulated Mg2+ dependent ATPase is demonstrated in mitochondrial fractions of the avian duodenum. Suppression of eggshell calcification resulted in a slight reduction in Mg2+, Ca2+ and Mg2+HCO-3 ATPase activities. Duodenal carbonic anhydrase activity was lower in birds laying soft-shelled eggs than in birds laying normal eggs. Alkaline phosphatase and calcium binding protein levels both decreased along the length of the small intestine, but the effect was more pronounced for alkaline phosphatase. Suppression of eggshell calcification and treatment of shell-less laying hens with 1,25(OH)2D3 influenced alkaline phosphatase activity only in the duodenal mucosa. Suppression of eggshell calcification reduced CaBP levels in all sections of the intestine. Treatment with 1,25(OH)2D3 restored CaBP levels. Regulation of intestinal CaBP levels by 1,25(OH)2D3 would therefore, seem to be controlled more directly by calcium requirements associated with eggshell calcification than by gonadal hormones.

Blood ionic calcium responses of hens from thick-shell and thin-shell lines to ethyleneglycol-bis-(B-aminoethylether)-N,N'-tetraacetic acid injections

Experiments were conducted on laying and nonlaying hens from genetically selected lines that produce thick (TK) or thin (TN) eggshells. At 44 weeks of age, TK layers exhibited significantly higher total plasma calcium concentrations than TN layers. Total plasma calcium concentrations were not significantly different between TK and TN layers at 80 weeks of age, reflecting an effect of aging on total plasma calcium. Intravenous injections of ethyleneglycol-bis-(B-aminoethylether-N,N'-tetraacetic acid (EGTA) were administered to TK and TN layers at 44 weeks of age and to TK and TN layers and nonlayers at 80 weeks of age. EGTA is a calcium chelating agent that creates hypocalcemia when injected intravenously. Laying hens of both lines and at both ages exhibited a similar degree of hypocalcemia during EGTA injections, and a similar rate of recovery to normocalcemia was noted after cessation of EGTA administration. Nonlayers were unable to recover from the EGTA-induced hypocalcemia. Because the pattern of calcium depression and recovery during and after the EGTA challenge has been shown to be associated with the capacity of parathyroid hormone-sensitive target tissues to buffer blood ionized calcium, it was concluded that the capacity to buffer ionized calcium by these target tissues is similar in TK and TN layers. However, nonlayers have a restricted capacity to buffer blood ionic calcium.

Bone parameters of thick and thin eggshell lines of chickens

Comparative measurements of bone parameters were made on chickens from thick and thin eggshell lines that were maintained on a normal diet containing 3.5% calcium, injected i.v. with 45CaCl2 and sacrificed 30 min later. There were no significant differences between shell lines for the following measurements on the left femur: specific gravity, ash wt, total calcium, percent calcium and 45Ca content. There was deposition of 45Ca in the femur of all hens--even those in the process of eggshell formation. Skeletal metabolism was not a limiting factor in determining whether a hen produced a thick or thin eggshell.

Effects of suppression of eggshell calcification and of 1,25(OH)2D3 on Mg2+, Ca2+ and Mg2+HCO-3 ATPase, alkaline phosphatase, carbonic anhydrase and CaBP levels--I. The laying hen uterus

Stimulation of Mg2+, Ca2+ and Mg2+HCO-3 dependent ATPase activity in mitochondrial and microsomal fractions from the uteri of laying hens is demonstrated. ATPase activity was greatest with 5 mM concentrations of Mg2+ at pH 8.5, and at pH 7.4-7.8 following the addition of bicarbonate. Suppression of eggshell calcification, induced by insertion of a thread into the uterus, did not alter Mg2+, Ca2+ and Mg2+HCO-3 ATPase activities. Alkaline phosphatase activity was generally low, and was unaffected by suppression of eggshell calcification. Levels of carbonic anhydrase and calcium binding protein were lower in the uteri of hens laying shell-less eggs. Injections of 1,25(OH)2D3 in hens laying shell-less eggs did not alter CaBP levels or enzyme activities. It is concluded that factors other than 1,25(OH)2D3 and gonadal hormones are involved in the regulation of uterine CaBP levels.

Influence of increasing dietary calcium and magnesium levels on performance, mineral metabolism, and egg mineral content of laying hens

The effects of increasing dietary magnesium level from .17 to .77% and calcium level from 3 to 4.2% for laying hens over a 7-week period was investigated. Increasing either dietary magnesium or calcium level had no significant effect (P greater than .05) on feed consumption, egg production, egg weight, or egg shell deformation. Increasing dietary magnesium level had no significant effect on calcium retention, although there was a significant (P less than .01) reduction in the percentage of magnesium retained. Egg shell calcium content was significantly (P less than .01) reduced and shell magnesium significantly (P less than .05) increased in response to increase in dietary magnesium content. Increasing dietary magnesium level also significantly (P less than .01) reduced bone calcium and zinc contents while concomitantly increasing bone magnesium levels. Bone ash and calcium were significantly (P less than .05) increased and bone magnesium reduced when the calcium content of the diet was increased. Plasma calcium was significantly (P less than .01) increased in dietary calcium level and significantly decreased with increased dietary magnesium. The converse was true for plasma magnesium in response to increases in dietary calcium and magnesium. Significant positive correlations were observed between mineral contents of diet and bone, bone and plasma, and plasma and shell. A negative correlation was observed between shell magnesium level and egg shell quality as assessed by deformation. An antagonistic relationship seems to exist between calcium and magnesium, and this is discussed in relation to skeletal integrity and egg shell quality.

The influence of dietary phosphorus level on laying hen performance, egg shell quality, and various blood parameters

The influence of dietary phosphorus on hen performance and egg shell quality was investigated. Total dietary phosphorus levels of .17, .23, .30, .40, .50, .70, 1.50, and 2.30% were fed to four body weight groups of 23-week-old White Leghorn hens. Hens consuming the diets containing .17, .23, and .30% phosphorus, all from plant origin, consumed significantly (P less than or equal to .05) less feed, which resulted in poorer performance than hens fed diets supplemented with inorganic phosphorus. Addition of supplemental inorganic phosphorus at levels of .10 to .40% resulted in the best overall hen performance. Plasma phosphorus was directly related to dietary phosphorus level. Egg shell quality as measured by specific gravity was inversely related to dietary phosphorus levels above .50%.

Calcium metabolism in broiler breeder hens. 2. The influence of the time of feeding on calcium status of the digestive system and eggshell quality in broiler breeders

Experiments were conducted to determine the influence of time of dietary calcium intake on eggshell quality in broiler breeder hens. In Experiment 1, 60 hens were randomly divided among three treatment groups. The control group received 155 g feed (3.1% calcium) per day at 0800 hr whereas the morning- (a.m.) and evening-fed (p.m.) treatments received a .42% calcium diet (155 g/bird) and were intubated with 4.2 g calcium at 0800 or 1600 hr, respectively. Egg weight, shell weight, and specific gravity were determined at 3-day intervals for 15 days. In Experiment 2, 150 breeder hens were randomly divided among two treatment groups. They were fed 122 g per hen during a 2.5-hr feeding time at 0700 to 0930 or 1530 to 1800 hr. Eggs were collected for egg weight, shell weight, and specific gravity determinations. At the end of the 5th week, 10 hens from each treatment group were sacrificed at various times throughout a 24-hr period and the contents of each segment of the GI tract and feces were analyzed for moisture, dry matter, and calcium. In Experiment 3, two commercial broiler-breeder houses with 5,000 hens each were used. They were fed 132 g/hen per day at 0530 hr daily with water provided ad lib. The feeding time of one house was moved forward by 2 or 2.5 hr per day until the feeding time was 1600 hr. Eggs were collected for 2 weeks following pretreatment data and values determined for specific gravity. Eggs were also candled at 7 days incubation to determine embryonic mortality and fertility. Hens intubated at 0800 hr with their daily supply of calcium did not maintain shell quality equivalent to controls (Experiment 1). However, hens intubated at 1600 hr had no difficulty maintaining shell quality. Hens fed at 1530 hr had significantly better shell quality during all weeks tested compared to hens fed at 0700 hr (Experiment 2). The p.m.-fed hens had 66.9% more calcium available at 1800 hr (2.07 vs. 1.24 g) compared to a.m.-fed hens. Hens fed at 1600 hr in the commercial houses (Experiment 3) had significantly better eggshell quality (specific gravity) than hens fed at 0530 hr. There was no significant difference in percent embryonic mortality or percent fertility when eggs were candled after 7 days of incubation. It was concluded that p.m.-fed hens had significantly more calcium available during the stages of eggshell calcification. The result was significantly better eggshell quality.

Chemical characterization of the hen eggshell matrix: isolation of an alkali-resistant peptide

The eggshell matrix was obtained from hen eggshells using EDTA solutions. The water-soluble organic material was separated on a DEAE-cellulose column equilibrated with 8 M urea using Tris-hydrochloric acid buffer as eluent with a linear gradient of sodium chloride. Five main fractions were obtained which differ in amino acid composition and sugar contents. As is shown from the uronic acid content, the first two fractions eluted from the column are glycoproteins, while the other three contain proteins and glycosaminoglycans From the alkaline hydrolysate of the eggshell matrix, a peptide was isolated which is composed of aspartic acid, threonine, serine, glutamic acid, proline, glycine and alanine in a molar ratio of 2:1:3:7:1:3:1 with a minimum molecular weight of 2158 daltons. The calcium ion binding to this peptide was studied, at different pH values, with both free and blocked carboxyl groups, using murexide as an indicator of free Ca2+. The importance of this acidic peptide in the calcification process of the eggshell matrix is discussed.

Effect of p-p'-DDE administered in vivo and in vitro on Ca2+ binding and Ca2+-Mg2+-ATPase activity in egg shell gland mucose of ducks

Thinning of the egg shell is produced by p-p'-DDT and DDE in several species of birds. A study was made of the effect of DDE administered in vitro and in vivo on the Ca2+ binding and Ca2+-Mg2+-activated ATPase of a homogenate of the egg shell gland of ducks (Anas platyrhynchos var.). The concentration of Ca2+ was 1 X 10(-4) M and that of MgATP 1 X 10(-3) M. In vitro, DDE in concentrations of 2-16 micrograms/ml of incubation medium inhibited the Ca2+-Mg2+-activated ATPase in a concentration-dependent manner, whereas Mg2+-activated ATPase was not affected by these concentrations. The Ca2+ binding by the homogenate was reduced by DDE in the same concentrations. The sodium azide sensitive Ca2+ binding was most sensitive. In vivo, DDE administered in a concentration of 40 mg/kg dry weight of the food for 45 days reduced the egg shell index by 18% in comparison to controls. After 45 days of treatment the DDE concentrations in the egg shell gland mucosa was 1.20 +/- 0.16 micrograms/g of wet weight, while no DDE was detected in the controls. The Ca2+-Mg2+-activated ATPase was reduced by 32%, whereas the Mg2+-ATPase was not changed. The Ca2+ binding by the homogenate was reduced by 29%, the sodium azide sensitive part being most vulnerable, DDE increased the total Ca content of the egg shell gland mucosa by 44%. Since Ca is transported against a concentration gradient between blood plasma, and the lumen of the shell gland, it is suggested that DDE, by inhibiting the Ca2+-Mg2+-activated ATPase, decreased the Ca translocation over the egg shell gland mucosa.

Lysine derived cross-links are present in a non-elastin, proline-rich protein fraction of Iguana iguana eggshell

1. Eggshell of Iguana iguana contains a variety of lysine-derived cross-linking amino acids apparently identical with some that occur in elastin. 2. Quantification of desmosine by amino acid analysis and radioimmunoassay gave estimates of 217 ng per mg and 109 ng per mg (dry weights), respectively. 3. [3H]NaBH4 reduction of eggshell protein established presence of lysine-derived aldehydes, allysine and allysine-aldol. 4. Enzymatic and chemical treatments indicate these cross-links occur in a non-elastin eggshell protein. 5. Iguana eggshell protein is unusually proline-rich, containing almost 440 proline residues per thousand.

The relationship of serum calcium to shell weight and other criteria in hens laying a low or high incidence of shell-less eggs

Experiments were conducted to determine the relationship of serum calcium to shell weight and other criteria. Blood samples for calcium analysis were taken at oviposition in Experiments 1 and 2 from hens fed a 3.5% calcium diet. In Experiment 3, blood was taken at various intervals from hens laying a high or low incidence of shell-less eggs. These hens were fed a control diet or various calcium-deficient diets throughout a 45-day period. No relationship was found between serum calcium and shell weight, or egg weight. Hens laying a high incidence of shell-less eggs showed no decrease in serum calcium or egg production when fed a .58, .25, or .07% calcium diet. However, these criteria were reduced in hens laying a low incidence of shell-less eggs. It was concluded that the normal variation in serum calcium is not related to the hen's ability to produce eggshell. The mechanism of action responsible for cessation of lay when control hens were fed a calcium-deficient diet appeared not to function as it does in hens laying a high incidence of shell-less eggs.