Production and characterization of eggs from hens with ovomucoid gene mutation.

Ovomucoid is a major egg white protein which is considered as the most dominant allergen in chicken eggs. Owing to the difficulty of separating ovomucoid from egg whites, researchers have adopted genetic deletion for development of hypoallergenic eggs. Previously, we used CRISPR/Cas9 to establish chickens with ovomucoid gene (OVM) mutations, but it remained unknown whether such hens could produce eggs at maturity. Here, we have reported on eggs laid by OVM-targeted hens. Except for watery egg whites, the eggs had no evident abnormalities. Real-time PCR revealed alternative splicing of OVM mRNA in hens, but their expression was limited. Immunoblotting detected neither mature ovomucoid nor ovomucoid-truncated splicing variants in egg whites. Sixteen chicks hatched from 28 fertilized eggs laid by OVM-targeted hens, and fourteen of the sixteen chicks demonstrated healthy growth. Taken together, our results demonstrated that OVM knockout could almost completely eliminate ovomucoid from eggs, without abolishing fertility. Thus, the eggs developed in this study have potential as a hypoallergenic food source for most patients with egg allergies.

Physicochemical and nutritional characteristics of preserved duck egg white.

In this paper, the physicochemical and nutritional characteristics of preserved duck egg white were analyzed and compared with fresh egg and hard-cooked egg white (n = 3). The data obtained showed that the preserved egg white was rich in essential amino acids and minerals, such as Ca, Mg, Fe, Zn, Cu, K, and Na. After fresh duck eggs were processed into preserved eggs, contents of moisture, CP, amino acid, and water-soluble vitamin of egg white significantly decreased (P < 0.05); however, pH, free amino acid content, and most inorganic elemental contents of egg white significantly increased (P < 0.05). The preserved egg white had higher a* (redness/greenness) and b* values (yellowness/blueness; P < 0.05) and lower L* value (lightness; P < 0.05) than hard-cooked egg white. The gel hardness of preserved egg white was approximately 50% of hard-cooked egg white; however, its springiness and cohesiveness were approximately 1.5 times of hard-cooked egg white. The results indicated that pickling with alkaline and other additives can significantly change physical properties and chemical composition of duck egg white, which make preserved egg white with characteristics of rich elements, brown color, and high springiness, but low vitamin.

Salmonella enteritidis deposition in eggs after experimental infection of laying hens with different oral doses.

The continuing attribution of human Salmonella Enteritidis infections to internally contaminated eggs has necessitated the commitment of substantial public and private resources to Salmonella Enteritidis testing and control programs in commercial laying flocks. Cost-effective risk-reduction requires a detailed and comprehensive understanding of how Salmonella Enteritidis infections in hens result in deposition of the pathogen inside eggs. The present study sought to resolve some incompletely defined aspects of the relationship between Salmonella Enteritidis oral-exposure dose levels in experimentally infected laying hens and the frequency and location of subsequent egg contamination. In two trials, groups of specific-pathogen-free hens were experimentally inoculated with oral doses of 10(4), 10(6), or 10(8) CFU of a phage type 4 Salmonella Enteritidis strain. Eggs were collected 5 to 23 days postinoculation, and the yolk and albumen of each egg were cultured separately to detect Salmonella Enteritidis contamination. Larger oral doses of Salmonella Enteritidis administered to hens were associated with significant increases in the frequencies of both yolk and albumen contamination. Moreover, Salmonella Enteritidis was found in the albumen of a far-higher proportion of contaminated eggs from hens given the largest dose than from the other two groups. Salmonella Enteritidis contamination was detected in 0.7% of yolk and 0.2% of albumen samples after inoculation of hens with 10(4) CFU, 4.0% of yolk and 1.7% of albumen samples after inoculation with 10(6) CFU, and 6.5% of yolk and 10.8% of albumen samples after inoculation with 10(8) CFU. These results demonstrate that oral-exposure doses of Salmonella Enteritidis for laying hens can significantly affect both the frequency and location of deposition of this pathogen inside eggs.

Effect of dry heating on the microbiological quality, functional properties, and natural bacteriostatic ability of egg white after reconstitution.

Spray-dried egg white (powder) is widely used in the food industry because of its variety of functional properties and its practical advantages. Moreover, egg white powder is generally considered safe because it can withstand high temperatures that allow for the destruction of all pathogens, especially Salmonella. In France, two types of treatments are used to improve the functional properties (whipping and gelling) of dried egg white: standard storage at 67 degrees C for about 15 days and storage at 75 to 80 degrees C for 15 days. The objective of this study was to investigate the effects of two dry-heating treatments (storage at 67 and 75 degrees C for 15 days) on the subsequent ability of egg white to resist Salmonella growth after reconstitution. The impact on the endogenous microflora of the powder and on its functional properties was also considered. Both dry-heating treatments were efficient in destroying a large number of Salmonella. Dry heating at 75 degrees C affected the bacteriostatic ability of reconstituted egg white to a greater extent than did dry heating at 67 degrees C. This loss of bacteriostatic ability could be attributable to the thermal denaturation of ovotransferrin, resulting in a reduction in its activity as an iron chelator. However, dry heating at 75 degrees C resulted in improved functional properties. Ultimately, no complete compromise between better functional quality and the preservation of the bacteriostatic ability of egg white after reconstitution is possible. Our results underline the importance of the use of hygienic conditions with egg white powder, especially with powder subjected to high-temperature treatments.

Effects of dietary 1, 4-diaminobutane (putrescine) on eggshell quality and laying performance of older hens.

We conducted an experiment to evaluate the potential for dietary 1,4-diaminobutane (putrescine) to promote eggshell quality and overall laying hen performance. A total of 128, 60-wk-old Barred Rock hens were fed a corn and soybean meal-based layer diet supplemented with 0.0 (control), 0.2, 0.4, and 0.6% free base 1,4-diaminobutane for 4 wk. The feeding of supplemental putrescine decreased feed consumption (P < or = 0.05) and egg mass (P < or = 0.05) and tended to decrease egg production (P < 0.08). Albumen quality was not significantly affected (P < 0.09) by the end of the experiment, as determined by Haugh units. Eggshell thickness was not significantly improved with lower levels of dietary putrescine (P < 0.08). Although dietary putrescine did not have any effect on the relative weights of duodenum, jejunum + ileum, or pancreas, there was a linear increase in putrescine concentrations in tissues (P < or = 0.05). Supplementation of dietary putrescine also resulted in increased putrescine and spermidine concentrations in egg (P < or = 0.05). Egg weight and eggshell deformation increased over time; however, eggshell weight, eggshell weight as percentage of egg weight, and eggshell thickness decreased (P < or = 0.05). It appeared that eggshell quality declined regardless of diet over the 4-wk experimental period. It was concluded that the lack of effect of dietary putrescine on egg parameters, with the exception of albumen quality and eggshell thickness, was due to putrescine toxicity. Hens transferred excess dietary putrescine and metabolites to eggs.

A problem with characteristics of the thin albumen in laying hens.

Industry observations indicate that a proportion of shell eggs exhibit an uncharacteristic spreading of the thin albumen when they are broken-out for fast-food preparation. Because the height and characteristics of the thick albumen are unaffected, the eggs are classified as Grade A. Preliminary observations discounted effects of egg storage or contaminated feed. Two experiments were conducted with Leghorn hens over a full laying cycle, and involved different levels of protein (14, 16, 18, or 20%) and associated amino acids, or different degrees of acid-base balance (150, 200, 250, or 300 mEq/kg). In each trial, treatments were represented by eight replicate groups of four adjacently and individually caged birds. Diet treatment had some effects on conventional production parameters, although there were no major effects on the area of the thin albumen produced when eggs were broken out. In Experiment 1, birds fed the highest level of protein produced eggs with the smallest thin albumen area; however, there was considerable bird to bird variation with thin albumen area varying from 69 to 122 cm2. Ten birds with compact (x 69 cm2) and 10 birds with spreading thin albumen (x 112 cm2) were inseminated with semen from a single, unrelated rooster. Offspring from these hens had significantly (P < 0.01) different thin albumen characteristics corresponding to those of their dams. Offspring producing eggs with the spreading thin albumen had the thickest eggshells as assessed by deformation measurement (P < 0.05). It is proposed that the excessively large spreading thin albumen area is caused by eggs spending more time in the shell gland.

The effect of different levels of vitamin C and cholecalciferol with adequate or marginal levels of dietary calcium on performance and eggshell quality of laying hens.

Three experiments were conducted to determine whether shell quality, bone mineralization, and other production traits could be improved by adding vitamin C (ascorbic acid) to laying hen diets. The period of each experiment was 12 wk. Experiment 1 consisted of a 2 x 2 x 3 factorial design with two levels of Ca (2.8 and 3.8%), two levels of cholecalciferol (vitamin D3; 2,200 and 4,400 IU/kg diet), and three levels of vitamin C (0, 125, and 250 ppm). Experiment 2 consisted of a 2 x 3 x 2 factorial design with two levels of Ca (2.8 and 3.8%), three levels of vitamin D3 (250, 500, and 2,000 IU/kg diet), and two levels of vitamin C (0 and 250 ppm). Experiment 3 consisted of a 2 x 4 factorial design with two sources of vitamin D3 (12.5 micrograms vitamin D3/kg diet or 12.5 micrograms 25-OH-D3/kg diet) and four levels of vitamin C (0, 250, 500, and 1,000 ppm). Calcium level was kept constant at 3.5% for all the diets in Experiment 3. Production performance was not influenced by dietary treatments in Experiment 1. In Experiment 2, feed conversion was improved (P < 0.05) due to increasing the dietary Ca, and egg weight and egg size were increased (P < 0.05) due to adding 250 ppm vitamin C to the diet. In experiment 3, albumen quality was increased by the addition of 1,000 ppm vitamin C to the diet. Egg specific gravity was increased in Experiments 1 and 2 only, due to increasing the Ca level (P < 0.05). In Experiment 2, increasing the Ca level and increasing the vitamin D3 level from 250 to 2,000 ppm reduced (P < 0.05) the number of cracked eggs, but incidence of cracked eggs was increased with the addition of 250 ppm vitamin C to the diet. In Experiment 1, plasma level of 1,25(OH)2D3 was greater (P < 0.05) for hens fed 2.8 than 3.8% Ca, but blood acidbase balance was not influenced by dietary regimens. Bone ash was not influenced by dietary treatments in any of the experiments. The data indicated that a supplemental level of vitamin C had no beneficial effects on shell quality and bone mineralization under the conditions of the current experiments.

Comparison between irradiated and thermally pasteurized liquid egg white on functional, physical, and microbiological properties.

A comparative study was undertaken to determine the effect of irradiation and thermal pasteurization on the functional, physical, and microbiological properties of liquid egg white (LEW). The LEW was irradiated or thermally pasteurized then stored at 4 C for 3 mo. Both treatments destroyed the inoculum, Salmonella typhimurium. The microbial growth rate was slower in the irradiated LEW than in the thermally pasteurized treatment. Irradiated samples had 47% lower foam drainage and more stable viscosity than samples that were thermally pasteurized. Volume of angel food cake prepared with irradiated or pasteurized LEW decreased 48 and 57%, respectively, after 90 d. Color did not differ between treatments. Ionizing radiation is an alternative processing method that inhibits microbial growth and helps maintain functionality of LEW.

Effects of dietary cottonseed meal and iron-treated cottonseed meal in different laying hen genotypes.

The effects of dietary screw-pressed cottonseed meal (CSM) and iron-treated CSM on laying performance and discolourations in eggs were examined in a range of hen genotypes. In experiment 1, six genotypes, obtained at point-of-lay from various sources, were fed on a non-CSM diet, a diet with 300 g CSM/kg, and a diet containing iron-treated CSM at 300 g/kg. In experiment 2, two of these genotypes were reared together from day-old and were fed from 10 to 18 weeks on a non-CSM diet or a diet containing iron-treated CSM at 250 g/kg. They were then fed on a non-CSM layer diet or a diet containing iron-treated CSM at 300 g/kg, in a 2 x 2 x 2 factorial design that also examined the effects of the rearing diet. 2. The effects on food intakes and egg production of including CSM and iron-treated CSM in layer diets depended on the genotype of the hens. The strongest interaction between breed and diet was on food intake, the breed Hubbard Golden Comet (HGC) being the least tolerant of CSM and iron-treated CSM. 3. Inclusion of iron-treated CSM in the rearer diet to supply approximately 70% of the dietary protein had no adverse effects on growth or age at first egg. Food intake and egg production between 18 and 26 weeks were affected by the iron-treated CSM layer diet, but there were no carry-over effects attributable to the rearing diets. 4. Genotype was not a factor in the development of the gossypol-related brown yolk discolouration in fresh or warm-stored eggs of hens fed on a CSM-based diet containing 197 mg free gossypol/kg and 52 mg cyclopropenoid fatty acids (CPFA)/kg (experiment 1). 5. In both experiments, the susceptibility of eggs to the CPFA-related cold storage effects depended on the genotype of the hen, eggs from hens of the HCG breed being more affected than those of ISA hens. 6. Treatment of CSM with crystalline ferrous sulphate heptahydrate, at a 4:1 weight ratio of iron to free gossypol, prevented brown yolk discolourations in all genotypes tested, as assessed by subjecting egg yolks to atmospheres of ammonia, and cold storage of eggs.

[Keeping quality of hard boiled eggs]. / Untersuchungen zur Haltbarkeit von hartgekochten Eiern.

Only a few and contradictory results are available on the storage stability of hard boiled eggs which are of considerable importance for institutional feeding. Therefore four storage experiments on about 500 hard boiled eggs each were carried out and chemical and sensorial changes occurring during storage investigated. The one-day-old eggs of the same origin were boiled for 17 minutes under standard conditions and subsequently stored in air at a relative humidity between 73 and 85% at 4 degrees C (experiment No. 1), at 20 degrees C (experiments No. 2 and 3) and in pure carbon dioxide at 20 degrees C (experiment No. 4). Immediately after boiling, the eggs used for experiments No. 3 were dipped into coloured resin for egg shells (natural Manila-Kopa; dissolved in ethanol and stained with "Acillantechtgrün). Losses in weight during storages were distincly lower in the lacquered eggs than in the non-lacquered samples otherwise treated in the same manner. The weight decrease caused by the loss of water was extraordinarily high in pure CO2 and is due mainly the the decrease of the pH in the egg whites caused by the uptake of CO2. A few days after boiling the concentration of the free amino acids reached approximately the same level in albumen and yolk and remained practically constant over the following 3 weeks. For the breakdown of lecithine in yolk determined according to Grossfeld and Peter, a "deterioration quotient" of 6, like in unboiled eggs, was fixed as the limit value for unspoiled condition. Accordingly a possible storage time of 3 to 4 weeks resulted for the eggs stored at 4 degrees C and for the eggs treated with stained resin. The non-lacquered eggs stored in air or in CO2 at 20 degrees C reached the critical value in about 10 days. From the vitamins A, B1 and B2 only vitamin A showed considerable losses during storage. On the basis of the microbiological (3) and chemical findings and of the sensorial evaluation of colour, consistency, odour and taste of egg whites and yolks, the following storage times were determined for eggs in the quality class "saleable" requiring an overall rating not lower than 6 (satisfactory): 14 to 16 days, for non-lacquered eggs stored at 4 degrees C and for lacquered eggs at 20 degrees C whereas 5 days were found to be the maximum storage time for untreated eggs stored at 20 degrees C. If boiled eggs are stored in pure carbon dioxide at 20 degrees C, a distinct quality loss is observed already after a few days.