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Heat resistance of Salmonella in various egg products.

The heat-resistance characteristics of Salmonella typhimurium Tm-1, a reference strain in the stationary phase of growth, were determined at several temperatures in the major types of products produced by the egg industry. The time required to kill 90% of the population (D value) at a given temperature in specific egg products was as follows: at 60 C (140 F), D = 0.27 min for whole egg; D = 0.60 min for whole egg plus 10% sucrose; D = 1.0 min for fortified whole egg; D = 0.20 min for egg white (pH 7.3), stabilized with aluminum; D = 0.40 min for egg yolk; D = 4.0 min for egg yolk plus 10% sucrose; D = 5.1 min for egg yolk plus 10% NaCl; D = 1.0 min for scrambled egg mix; at 55 C (131 F), D = 0.55 min for egg white (pH 9.2); D = 1.2 min for egg white (pH 9.2) plus 10% sucrose. The average Z value (number of degrees, either centigrade or fahrenheit, for a thermal destruction time curve to traverse one logarithmic cycle) was 4.6 C (8.3 F) with a range from 4.2 to 5.3 C. Supplementation with 10% sucrose appeared to have a severalfold greater effect on the heat stabilization of egg white proteins than on S. typhimurium Tm-1. This information should be of value in the formulation of heat treatments to insure that all egg products be free of viable salmonellae.

Egg White↗

Vitamin profiles of eggs as indicators of nutritional status in the laying hen: vitamin B12 study.

Hens of a type used for egg production were fed a corn and soybean meal diet supplemented with no vitamin B12 or with vitamin B12 levels to provide one, two, or four times the National Research Council (1984) breeding hen requirement of 4 micrograms/kg diet for 27 wk. All hens were placed on a recovery diet containing one and one-half times the requirement level of vitamin B12 from Weeks 27 through 30. Egg yolk vitamin B12 concentrations were determined frequently by radioisotope dilution analysis. Egg production records were kept continuously, and eggshell thickness, egg weight, hatchability of eggs, and hen body weights were measured at selected times. Although egg yolk vitamin B12 concentrations were high at the outset, they decreased markedly in 2 wk from hens fed the two lowest dietary levels. After 12 wk on the diets, egg concentrations of vitamin B12 stabilized and were proportional to the amount of vitamin added to the diet. Egg concentrations of vitamin B12 between 1.3 and 2.6 micrograms/100 g yolk appeared to be needed to support maximum hatchability and egg weight. Egg production was reduced after 12 wk on the diets in the hens fed the two lowest vitamin B12 levels. As vitamin B12 level increased, shell thickness decreased and egg weight, hen weight, and hatchability increased. Maximum egg production, egg weight, hen weight, and hatchability were obtained when the diet contained 8.0 micrograms/kg of vitamin B12. Egg yolk vitamin B12 concentrations respond rapidly to dietary changes in the level of this vitamin and are indicative of the vitamin B12 status of the hen.

Animals↗

Applying tests for specific yolk antibodies to predict contamination by Salmonella enteritidis in eggs from experimentally infected laying hens.

Detecting Salmonella enteritidis contamination in eggs has become the cornerstone of many programs for reducing egg-borne disease transmission, but egg culturing is time consuming and laborious. Preliminary screening tests are thus generally applied to minimize the number of flocks from which eggs must be cultured. The usefulness of such tests is directly proportional to both their detection sensitivity and their ability to predict the likelihood of egg contamination. In the present study, samples were collected for 24 days after groups of laying hens were orally inoculated with S. enteritidis. Eggs from each hen were cultured for S. enteritidis in the contents and samples of egg yolk were diluted and tested for specific antibodies to S. enteritidis flagella using both experimental and commercially available enzyme-linked immunosorbent assay (ELISA) methods. Samples of voided feces were also collected regularly from each bird and cultured for S. enteritidis. Although fecal shedding and egg yolk antibody production followed opposite patterns over time (fecal shedding was decreasing as egg yolk antibody titers were increasing), tests for both parameters were effective in predicting whether particular hens would lay contaminated eggs. Among hens that laid at least one egg contaminated by S. enteritidis, 82% were detected as infected by fecal culturing and 96% by the experimental egg yolk ELISA test. Using easily collected samples, egg yolk antibody testing offers a rapid and effective screening method for identifying S. enteritidis-infected laying flocks that might lay contaminated eggs.

Animals↗

Comparison of physical quality and composition of eggs from historic strains of single comb White Leghorn chickens.

The effect of long-term genetic selection on physical quality and composition of eggs was determined by analyzing eggs acquired from Agriculture Canada: Ottawa Control Strain 5 (CS5) from a 1950 base population, 7 (CS7) from a 1958 population and 10 (CS10) from a 1972 population. Eggs from the H&N "Nick Chick" current commercial strain (CCS) were also included. Eggs were collected monthly over a 62-wk laying period and analyzed for egg, albumen, shell and yolk weight; albumen protein, solids and pH; percentage yolk solids and fat; Haugh units; and specific gravity. Significant (P < 0.05) differences found between strains included a progressive increase in weight of eggs from the CS5 to CCS. Although the eggs increased in size, no significant differences were found between strains for specific gravity or percentage shell weight. Yolk weights of eggs from the strains examined did not differ. However, the percentage of yolk found in current strain eggs was significantly lower (P < 0.05), with a subsequent higher percentage albumen due to the increase in egg size of the CCS. Haugh units were significantly higher in the CS10 and CCS strains than in the other strains. No significant differences between strains were seen in albumen protein, solids, pH, or yolk solids. Mean percentage yolk fat assay values for eggs from the CS5, CS7, CS10, and CCS strains were 33.08, 32.68, 32.84, and 32.40, respectively. Percentage yolk fat values obtained from CCS were significantly lower (P < 0.05) than those obtained from the other strains. The results from this study indicate that genetic selection has produced larger eggs containing a lower percentage of yolk while overall egg quality has been maintained or improved.

Aging↗

Different patterns of faecal egg output following infection of Scottish blackface lambs with Ostertagia circumcincta.

Faecal nematode egg counts were monitored in 184 Scottish Blackface lambs during natural exposure to a mixed, predominantly Ostertagia circumcincta infection and 12 lambs were selected which showed consistently zero (low count group; nine lambs) or consistently positive faecal egg counts (high count group; three lambs). These lambs were then treated with anthelmintic and challenged with 50,000 infective larvae of O. circumcincta and monitored thrice-weekly for 38 weeks; they were then re-challenged with another 50,000 infective larvae of O. circumcincta and monitored for a further 8 weeks. All sheep gave positive egg counts following deliberate infection. However, there was considerable variation among sheep in the size and timing of the peak in egg production. In particular, the pattern of mean values for faecal egg counts was different in the two groups. Egg counts were lower in the later periods of the extended infection in both groups of sheep. During the first half of the extended infection, egg counts were lower in sheep from the low count group, but during the second half of the infection the pattern was reversed and egg counts were lower in sheep from the high count group. There was a weak positive correlation between egg counts following anthelmintic treatment and 28 days exposure to natural infection and egg counts 28 days after a deliberate infection. Egg counts in the later stages of the deliberate infection were strongly but negatively correlated with egg counts following natural infection. The results of these studies show that differences in egg count following natural infection can be reproduced in experimental infections and that there is substantial variation in the pattern of egg production over time in different sheep. They also suggest that naturally resistant lambs are better able to delay worm development than naturally susceptible lambs.

Abomasum↗

Eggshell factors influencing eggshell penetration and whole egg contamination by different bacteria, including Salmonella enteritidis.

Trans-shell infection routes and whole egg contamination of 7 selected bacterial strains; Staphylococcus warneri, Acinetobacter baumannii, Alcaligenes sp., Serratia marcescens, Carnobacterium sp., Pseudomonas sp. and Salmonella enteritidis, recovered from egg contents, were studied. The first objective was to correlate bacterial eggshell penetration with various eggshell characteristics and bacterial strains. An agar approach was used to assess the eggshell penetration. The second objective was to assess the contamination of whole eggs with the bacterial strains; whole intact eggs were used in this case. The intact shells of agar-filled and whole eggs were inoculated with 10(3) -10(4) cfu of the selected strains. During 3 weeks storage at 20 degrees C and 60% relative humidity, the bacterial eggshell penetration was regularly monitored. The whole egg contamination was only analyzed after 3 weeks. The eggshell characteristics such as area eggshell, shell thickness and number of pores did not influence the bacterial eggshell penetration. For each individual bacterial strain the mean cuticle deposition was lower for penetrated compared to non-penetrated eggshells. For the individual strain Carnobacterium sp. and for the global results of all strains this difference was statistical significantly. The whole egg contamination was not influenced by neither the area of the eggshell nor the porosity of the eggshell. The results of the agar approach indicate that the Gram-negative, motile and non-clustering bacteria penetrated the eggshell most frequently; Pseudomonas sp. (60%) and Alcaligenes sp. (58%) were primary invaders followed by S. enteritidis (43%). All selected strains were able to penetrate; penetration was observed most frequently after ca. 4-5 days. Particularly S. enteritidis was a primary invader of whole eggs: the membranes and/or the content of 32% of the whole eggs was contaminated. The remaining bacterial eggshell contamination with the selected strain was determined after 3 weeks storage. Penetrated eggshells and contaminated whole eggs showed a significantly higher bacterial contamination on the eggshell compared to non-penetrated eggshells and non-contaminated whole eggs respectively (global results of all strains). The influence of hen age on bacterial eggshell penetration and egg content contamination was not significant. While the agar approach is suitable to study the influence of the eggshell characteristics on the bacterial eggshell penetration, the intact egg approach gives an estimation of the penetration of the shell followed by the probability of survival and migration in whole eggs.

Animals↗

The effect of desiccation and low temperature on the viability of eggs and emerging larvae of the tick, Rhipicephalus (Boophilus) microplus (Canestrini) (Ixodidae).

Process-based population models need sound and comprehensive data on an animal's response to climatic factors if they are to function reliably under a wide range of climatic conditions. To this end, different aged egg masses of the livestock tick, Rhipicephalus (Boophilus) microplus, were either desiccated in atmospheres with saturation deficits of 5, 10, 15 or 20 mmHg at 20 or 26 degrees C, or chilled at temperatures of 5, 10 or 14 degrees C with a saturation deficit of 1 mmHg for varying periods. The survival rate of the eggs through to hatching was related to the initial age of the eggs, the severity of the treatments and the duration of exposure. We established a relationship between desiccation and weight loss of eggs and, secondarily between weight loss and mortality. Mortality increased with weight loss until it reached 100% when the weight loss was about 35%. Low temperatures were increasingly detrimental to eggs as they reduced from 14 to 5 degrees C. Freshly laid eggs were more susceptible to both low temperatures and desiccation than were older eggs. Larvae emerging from eggs that were stressed by either cold or desiccation lived for a shorter time under optimal conditions than did larvae from eggs incubated under optimal conditions. Larvae from eggs with the same hatching rate had the same viability, whether the stress was induced by desiccation or low temperatures. Models were developed to describe the dynamics of weight loss of eggs with desiccation, the accumulation of cold stress of the eggs, and their effects on egg survival and larval viability. These data provide a sound basis for the development of predictive models for use under field conditions, although the response of different aged eggs to low temperatures was too variable to allow us to develop an accurate model to describe that relationship. Field models will also need to take diurnal temperature fluctuations into account.

Animals↗

Influence of holding temperature on the growth and survival of Salmonella spp. and Staphylococcus aureus and the production of staphylococcal enterotoxin in egg products.

In this study, growth and survival of Salmonella spp. and Staphylococcus aureus in steamed egg and scrambled egg held at 5, 18, 22, 37, 55 and 60 degrees C are investigated. The production of staphylococcal enterotoxin in steamed egg is also examined. Results reveal that Salmonella spp. and Staph. aureus in the egg products multiply best at 37 degrees C, followed closely by 22 and 18 degrees C. Neither pathogen showed growth in the egg products held at 5 degrees C. Initial inoculation dose, holding temperature and holding time affected the population of both organisms found in the egg products. Staphylococcal enterotoxin A (SEA) and B (SEB) are detected only in the egg products held at 37 or 22 degrees C. After holding at 37 degrees C for 36 h, scrambled egg inoculated with ca. 5.0 log cfu/g Staph. aureus contains the highest levels of SEA (> 64 ng/g) and SEB (> 64 ng/g). Although Salmonella spp. and Staph. aureus grow better in steamed eggs than in scrambled eggs, production of staphylococcal enterotoxin, in general, was higher in scrambled eggs than in steamed eggs. On the other hand, a repaid destruction of the test organisms in steamed eggs held at 60 degrees C was observed. Holding the steamed eggs at 60 degrees C, Salmonella spp. and Staph. aureus with an initial population of ca. 5.9 and 5.6 log cfu/g, respectively, reduced to a non-detectable level in 1 h.

Colony Count, Microbial↗

The fatty acid composition of oophagous tadpoles (Chirixalus eiffingeri) fed conspecific or chicken egg yolk.

We compared the lipid content and fatty acid composition of (1) the egg yolk of three anuran species (Chirixalus eiffingeri, Rhacophorus moltrechti and Buergeria robustus) and chicken eggs; and (2) C. eiffingeri tadpoles fed conspecific eggs or chicken egg yolk. Anuran and chicken egg yolk contained more non-polar than polar lipids but the proportions varied among species. Chicken egg yolk contained low amounts of 22:5n-3 in the polar lipid fraction, and B. robustus eggs did not contain any n-3 or n-6 non-polar lipids. The specific variation of lipid contents and fatty acid composition may relate to the maternal diet and/or breeding biology. In C. eiffingeri tadpoles that fed chicken yolk or frog egg yolk, the dominant components of polar and non-polar lipids were 16:0, 18:0, 18:1, and 18:2n-6, or 20:4n-6 fatty acids. C. eiffingeri eggs contained more n-3 fatty acids (e.g. 18:3n-3 and 20:5n-3) than chicken egg yolk, and tadpoles fed conspecific eggs contained more of these fatty acids than tadpoles fed chicken egg yolk. The compositional differences in the fatty acids between C. eiffingeri tadpoles that fed frog egg or chicken egg yolk are the reflection of the variation in the dietary sources. Our results suggest a direct incorporation of fatty acids into the body without or minimal modification, which provide an important insight into the physiological aspects of cannibalism.

Animal Feed↗

Cellular immune responses to ovalbumin and house dust mite in egg-allergic children.

BACKGROUND: Although IgE-mediated food (egg) allergy is typically lost with age the underlying immune mechanisms are not understood, particularly in relation to the development of persistent IgE-mediated aeroallergen sensitivity. METHODS: Lymphoproliferation and cytokine responses (IL-5, IL-10, IL-13 and IFN-gamma) to house dust mite (HDM) allergen and egg ovalbumin (OVA) were assessed using peripheral blood mononuclear cells (PBMC) from children aged 6 months to 5 years (n = 59) with acute IgE-mediated egg allergy (urticaria and angiedema or anaphylaxis), as confirmed by positive skin prick testing (SPT). Of these 46 had positive SPT on the day of blood collection and 13 had outgrown egg allergy (negative SPT and successful egg challenge). Where possible, responses were compared with previous data from nonallergic children of similar ages (n = 107). RESULTS: Transient lymphoproliferative responses to OVA were seen in both egg-allergic and nonallergic children, but were more marked and more prolonged in egg-allergic children. Younger egg-allergic children (< 18 months) showed a mixed Th0 cytokine response to OVA, with readily detectable IFN-gamma, IL-5, IL-13 IL-10. Although IL-13 and IL-5 responses (OVA) correlated in younger egg-allergic children, there was a dissociation of these Th2 responses with age. Loss of clinical reactivity to egg was associated with almost complete loss of IL-5 responses and OVA-specific lymphoproliferation. Although IL-13 levels tended to be lower with age, this was not significant. Strong IFN-gamma and IL-10 responses to OVA persisted in older children after loss of OVA-specific lymphoproliferation. Lymphoproliferative responses to HDM also developed earlier in egg-allergic children compared with nonallergic children. Th1 (IFN-gamma) responses to HDM were largely below detection prior to 18 months of age, but increased significantly with age. In egg-allergic children Th2 (IL-5, IL-13) HDM responses also progressively increased with age. At 3 years of age almost all egg-allergic children had positive SPT to HDM and positive lymphoproliferative responses to HDM, with strong Th1 and Th2 (Th0) cytokine production. CONCLUSIONS: IL-5 responses (rather than IL-13) responses most closely reflected clinical food allergy, with dissociation of IL-5 and IL-13 responses in older and egg-tolerant children. In this population, food and aeroallergen sensitivity was not associated with inability to produce IFN-gamma, but rather with mixed Th2 and Th1 (Th0) responses. Strong IL-10 and IFN-gamma responses where associated with the development of tolerance, suggesting persistent 'regulatory' populations of OVA-specific T cells, rather than clonal deletion of OVA responsive T-cells.

Animals↗

Effect of intensity of eggshell pigment and illuminated incubation on hatchability of brown eggs.

The effects of intensity of brown eggshell pigment (light (LBP), medium (MBP) and dark (DBP)) and light intensity during incubation (low and high, 900 to 1380 and 1430 to 2080 lux, respectively) on eggshell characteristics, embryonic growth, hatchability traits, chick hatching weight and hatching time were investigated using eggs from a meat-type breeder (Hybro) flock at 32, 36 and 41 weeks of age in three trials. With eggs of similar weights the intensity of brown pigment was not associated with eggshell weight and thickness, and did not influence embryo weight and egg weight loss during incubation. The shade of brown pigment of eggs laid by young hens influenced the percentage hatchability (HP) of eggs incubated under light. Illuminated incubation improved HP of LBP eggs (compared with MBP and DBP eggs) from 32- and 36-week-old hens, but had no significant effect on HP of eggs from 41-week-old hens. Light intensity during incubation did not influence egg weight loss. High intensity of light during incubation reduced HP and increased early death percentage (EDP) in the LBP and MBP groups, and did not influence HP and EDP in the DBP group. Brown eggshell pigment and intensity of light during incubation did not influence hatching time. It is concluded that the shade of brown pigment, intensity of light during incubation and age of the breeder hens influenced the hatchability performance of embryos from brown eggs. Light during incubation improved the hatchability of embryos in light brown eggs laid by young hens and the shade of brown pigment of eggs laid by older hens did not influence hatchability under illuminated incubation. High intensity of light during incubation reduced hatchability of light and medium brown eggs, but not the dark brown eggs.

Animals↗

Increment of egg weight with hen age in various commercial avian species.

1. The present study indicates that a common biological pattern exists for egg weight increase with hen age for the various commercial avian species, breeds and strains at their first laying cycle. Therefore, one common equation can be used for the estimation of egg weight increase. 2. The parameters estimated for this equation are based on (a) egg weights in terms of percentage of seasonal mean egg weight, and (b) age as percentage of maximum age of the hen. Therefore, if the season's mean egg weight is known for any species, breed or strain, the increase in egg weight can be easily predicted for the whole season, or for any particular hen age. For early prediction, egg weight expressed as a percentage of initial egg weight can be used, although such prediction will be somewhat less accurate. 3. The use of egg weight as a percentage of seasonal mean egg weight, and age as a percentage of maximum age, was found to overcome the differences between strains, breeds and even species, by applying the same denominators for egg weights and periods of lay. 4. At each point of hen age (mean egg weight), the egg weight grades can be easily estimated by employing the computerised Burr's (1967) equation. These values showed excellent fit with extensive field data, provided that only normal eggs and those originating from a single flock and from no more than two weeks of collection are counted.

Animals↗

Identification of a sperm receptor on the surface of the eggs of the sea urchin Arbacia punctulata.

The possibility that the surface of the egg of the sea urchin Arbacia punctulata contains a species-specific receptor for sperm has been investigated. The extent of fertilization of eggs of A. punctulata, which is proportional to the number of sperm, is unaffected by the presence of either eggs or membranes prepared from eggs of Strongylocentrotus purpuratus. In marked contrast, membranes prepared from eggs of A. punctulata quantitatively inhibit fertilization of A. punctulata eggs by A. punctulata sperm. Several lines of evidence indicate that this inhibition is due to the presence of a membrane-associated glycoprotein that binds to the sperm, thus preventing them from interacting with receptor on the surface of the eggs. First, eggs treated with trypsin are incapable of being fertilized, although they can be activated with the Ca2+ ionophore A23187. Moreover, membranes prepared from eggs pretreated with trypsin do not inhibit fertilization of eggs. Second, receptor isolated in soluble form from surface membranes binds to sperm and thus prevents them from fertilizing eggs; the inhibition by soluble receptor is species-specific. Third, the soluble receptor binds to concanavalin A-Sepharose. Fourth, eggs are incapable of being fertilized if they are pretreated with concanavalin A. The specificity of inhibition, and the affect of trypsin and concanavalin A on intact eggs, suggest that the receptor is a species-specific macromolecule located on the surface of the eggs. The sensitivity of the receptor to trypsin, and its ability to bind to concanavalin A, indicate that it is a glycoprotein.

Animals↗

Correlated responses to long-term selection for clutch length in dwarf brown-egg layers carrying or not carrying the naked neck gene.

Two dwarf brown-egg layer lines, differing in their genotype for the naked neck gene (NA), line L2 (NA*NA/*NA) and line L1 (NA*N/*N), have been selected for 16 generations for increased average clutch length. A control line from the same base population, dwarf and segregating for the NA gene, was maintained by random mating. Genetic parameters were estimated by a multivariate derivative-free restricted maximum likelihood procedure, and the NA gene effect was estimated within the unselected control line. The studied traits included clutch traits, egg production traits, abnormal eggs, egg weight at 36 wk, and BW at 42 wk. The average clutch length, egg number, and maximum clutch length were normalized using the Box-Cox transformation. In response to 16 generations of direct selection for increased average clutch length, other egg production traits, such as laying rate and total egg number, have been indirectly improved in a dwarf layer genetic background. The estimated heritabilities were 0.406 to 0.424 for transformed average clutch length (TCL), 0.373 to 0.411 for transformed egg number (TEN), 0.529 to 0.559 for age at first egg (AFE), 0.275 to 0.282 for laying rate (LR), 0.455 for dutch number (CN), and 0.319 for the number of double-yolked eggs (DYEN). The TCL had high genetic correlations with TEN (0.777), LR (0.863), maximum clutch length (0.902), and CN (-0.845). Selection for increased average clutch length was an effective method for increasing egg production. Line L2 showed a higher egg weight than L1, which indicates that the combined effect of NA and DW genes was favorable to maintain egg weight when egg number could be improved. Line L1 showed a higher number of DYEN, suggesting that the regulation of follicular maturation was changed in this line.

Animals↗

Evaluation of a method of ultraviolet light sanitation of broiler hatching eggs.

Sanitation of hatching eggs is an important area of research due to the need for an effective, economical, and safe method of egg sanitation. Improved hatching egg sanitation is an important part of an overall pathogen reduction program within integrated poultry operations. This must be accomplished without disturbing the cuticle of the egg, which can decrease hatchability. The ability of ultraviolet (UV) light to kill bacteria on eggshell surfaces has been well documented. To accomplish the task of treating the eggs in a method that could be commercially implemented, a cabinet was constructed in which ultraviolet lamps were placed. A conveyor system was used to carry a plastic hatching egg flat containing 42 eggs through the cabinet for a period of 3 or 4 min. Ultraviolet intensities within the cabinet reached a maximum of 14 mW/cm2. Experiments were conducted to test the impact of UV light (254 nm) exposure of hatching eggs on aerobic plate counts (APC), inoculated Salmonella typhimurium and inoculated Escherchia coli. In the first three experiments, seven eggs were sampled from a flat passed through the UV chamber. Ultraviolet-treated eggs compared to untreated eggs had APC reductions of 1.3 log, S. typhimurium had a 4 log reduction, and E. coli had a 4 to 5 log reduction. Laboratory trials were also conducted to test the effects of UV irradiation on the cuticle of the egg and hatchability. No significant differences for eggshell conductance or hatchability were found between UV-treated and control eggs. From these trials, it can be concluded that UV irradiation of hatching eggs in a prototype irradiation cabinet can effectively reduce aerobic and pathogenic bacteria on eggshell surfaces without affecting eggshell conductance or hatchability.

Animals↗

A case retaining contact urticaria against egg white after gaining tolerance to ingestion.

A girl, 5.7 years old, gained tolerance to egg white ingestion in spite of high immunoglobulin E (IgE) antibody titers to egg white but retained contact urticaria against egg white. She developed atopic dermatitis on her face at 2 months of age and showed high IgE antibody titers to egg white and cow's milk. Accidental ingestion of egg products initiated immediate symptoms such as wheezing, urticaria, erythema and edema of the eyelids and conjunctiva three times. These symptoms were confirmed by challenge tests using boiled egg white at 3.9 years of age. She also reacted positively to a 20 min patch test on her volar arm with raw egg white. However, there were no reactions to the oral challenge test by boiled egg and freeze-dried egg white at 5.1 and 5.7 years of age, respectively. This non-responsiveness was confirmed by a double-blind, placebo-controlled food challenge using freeze-dried egg white. Nevertheless, she showed positive reactions to a 20 min patch test with freeze-dried egg white. Her IgE antibody titers to the egg white components including ovomucoid, ovalbumin, ovotransferrin and lysozyme as well as egg white were high from 2.9 to 5.7 years old. Her IgE antibody titers for the ovomucoid fragments digested by pepsin, chymotrypsin and trypsin were not lower than those of positive control subjects. The binding activity of IgE antibody to ovomucoid, however, decreased from 2.9 to 5.6 years as shown by radioallergosorbent test (RAST) inhibition assays. The IgE antibody showed weaker binding activity to pepsin- and chymotrypsin-digested ovomucoid that were filtered through cut-off 10,000 filter at the age of 2.1 and 5.7 years. We speculated that the maturation of secretion of digestive enzymes was involved in the mechanisms of the acquisition of tolerance to egg white ingestion in spite of the persistence of contact urticaria.

Antibody Affinity↗

Influence of percent egg yolk during cooling and freezing on survival of bovine spermatozoa.

The influence of percent egg yolk during cooling from 37 to 5 C on ability of sperm to withstand subsequent freezing was studied with semen from each of eight bulls. Treatments were arranged factorially and included .5, 1, 2, 4, 8, 16, and 32% egg yolk, cooling times of .5, 1, 2, and 4 h, and freezing in ampules and straws. Percent egg yolk did not influence motility or percent intact acrosomes when semen was frozen in ampules. For sperm in straws, both post-thaw percentages of motile sperm and intact acrosomes were similar for sperm cooled with .5, 1, 2, 4, or 8% egg yolk and greater than with 16 or 32% egg yolk. Optimal egg yolk during cooling was not dependent upon rate of cooling, regardless of how semen was packaged for freezing. The influence of percent egg yolk during freezing was investigated in a second study. Treatments included eight bulls; 1, 2, 4, 8, 16, and 32% egg yolk; freezing times from +5 to -130 C of 3.5, 20, and 40 min; and freezing in ampules or straws. Optimal egg yolk during freezing in either ampules or straws was independent of the rate of freezing. For sperm frozen in ampules, differences in motility or the percent intact acrosomes due to egg yolk were small. However, the use of only 1 or 2% egg yolk depressed motility whereas 16 or 32% egg yolk decreased the percentage of intact acrosomes. Thus, extremely high or low egg yolk should be avoided. For sperm in straws, survival was optimal when the extended semen contained 4 to 32% egg yolk during freezing.

Animals↗

Effects of vitamin E-enriched egg yolk on lipid peroxidation, hemolysis and serum lipid concentration in young and old rats.

Effects of a diet containing different amount of vitamin E-enriched egg yolk powder on lipid peroxidation, hemolysis, and serum lipid concentration were examined in young and old rats. Young and old rats were fed experimental diets containing 5.6% or 22.5% of normal egg yolk powder, and 5.6% or 22.5% of vitamin E-enriched egg yolk powder. When young rats were fed these diets, their tocopherol concentrations in testes, heart, kidneys, and retroperitoneum fat pads increased according to the diet tocopherol contents. Lipid peroxide levels in these tissues were inversely proportional to the tocopherol concentrations. The liver and serum, however, did not show the above relationship. In the rats fed vitamin E-enriched egg yolk diets hemolysis did not increase, in contrast to those fed normal egg yolk diets. The rats fed a 5.6% vitamin E-enriched egg yolk diet had a lower serum cholesterol level than those fed a normal egg yolk diet. In old rats, one control group was used to determine initial tocopherol concentration and two other groups were fed 5.6% normal and vitamin E-enriched egg yolk diets. The vitamin E-enriched egg yolk rats showed lower weights of the body, liver, and retroperitoneum fat pads at the end of the experiment. The normal egg yolk group had atrophied testes. The tissue and serum tocopherol concentrations were increased in the vitamin E-enriched egg yolk group, whereas they were decreased in the normal egg yolk group. In the vitamin E-enriched egg yolk group, lipid peroxide, hemolysis and serum cholesterol, especially HDL-cholesterol, did not increase. These results indicate that egg yolk tocopherol was absorbed and prevented lipid peroxidation and hemolysis in young and old rats, and testes atrophy in old rats.

Age Factors↗