2. There were no significant differences between egg types in terms of egg shape index, eggshell strength and thickness, albumen height, Haugh unit, yolk colour, weight of the eggshell with or without membranes, calcium, phosphorus, copper and manganese contents in the eggshell (with the inner and outer membranes or without the inner membrane), albumen weight, dry matter of albumen, crude protein (CP) of thick albumen and pH of the thick albumen.
3. The weight of eggshells with membranes, weight of thick albumen and CP of thin albumen in striped eggs were lower than those in normal eggs.
4. The thin albumen in striped eggs was heavier than that in normal eggs. The pH of the thin albumin in striped egg was significantly higher than that in normal eggs.
5. There were no significant differences in EW loss during incubation or duckling weight between striped and normal eggs. However, the hatchability of striped eggs was lower.
6. The lower weight of the eggshell inner membrane and thick albumen, lower CP content and higher pH in the thin albumen of striped eggs might contribute to lower hatchability. 相似文献
2. For incubated eggs the sodium concentration of albumen adjacent to the yolk sac was lower than that from albumen next to the shell. Static incubation increased the magnitude of this difference, such that albumen adjacent to the yolk sac was substantially depleted of sodium. This was found at the yolk equator and the yolk vegetal pole of both fertilised and unfertilised eggs.
3. Unincubated eggs also had a lower sodium concentration of albumen adjacent to the yolk sac compared with albumen next to the shell.
4. After 48 h of incubation yolk sodium concentration was substantially lower than albumen sodium concentration in both fertilised and unfertilised eggs, whether eggs were turned or not.
5. It is concluded that in unturned eggs the depletion of sodium from albumen adjacent to the vitelline membrane is not produced by ion transport processes but results from a passive movement of sodium into the yolk. Egg turning reduces the magnitude of the depletion of sodium from the albumen adjacent to the yolk sac by stirring the albumen, so permitting the full expression of ion and water transport across the blastoderm into the yolk sac. 相似文献
2. The density of albumen increased, and the density of yolk sac contents decreased, during the first 5 d of incubation. Failure to turn eggs diminished these changes.
3. The rate of formation of SEF and its maximum weight were lower if eggs were not turned, as was the rate of decrease in albumen weight.
4. The concentration of sodium and chloride, as well as osmolality, were higher in SEF than in thin albumen, and were affected by a failure to turn eggs.
5. Static incubation altered the concentrations of yolk nutrients in SEF.
6. It is concluded that the formation of SEF is primarily dependent upon the transfer of sodium and chloride from albumen to SEF so creating an osmotic force for water movement in the same direction. Turning the eggs promotes this process by ensuring an adequate supply of ions in thin albumen adjacent to the blastoderm. 相似文献
2. Oiling slowed the decline in albumen height (Haugh units) to that which occurred in unoiled eggs stored at 12 °C.
3. Oiling slowed the increase in albumen pH equally at 28 and 12 °C.
4. Oiling markedly decreased the weight loss of eggs stored at either temperature.
5. Oiling and temperature of storage were without effect on the whipping volumes of either albumen or unseparated albumen and yolk. 相似文献
It was concluded that:
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The variations in calcium concentration reflected both the known uptake of this ion by the albumen and medullary bone formation and destruction.
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The variations in magnesium concentration did not parallel the changes in calcium concentration.
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Magnesium was released into the blood during medullary bone formation.
2. Discolouration prevention methods included treating the meal with ferrous sulphate heptahydrate (FSH), in solution or as crystals, at a 4:1 weight ratio of iron to free gossypol (experiment 1), and reducing its residual lipid (CSL) content to 4.2 g/kg by hexane extraction (experiment 2).
3. In freshly laid eggs, no discolouration was observed when hens were fed a CSM‐based diet containing 250 mg free gossypol/kg and 87 mg CPFA/kg in experiment 1, but slightly brown yolks were produced in experiment 2.
4. Storage of the eggs at 22°C led to yolk mottling, an effect believed to be the initial stages of the brown yolk discolouration.
5. Storage of the eggs at 5°C resulted in enhancement of the brown yolk discolouration, apricot discolouration on surfaces of most yolks and pink albumen discolouration. These effects were prevented when the CSM was extracted with hexane. Apricot yolk and pink albumen discolourations were also produced when hens were fed a non‐CSM diet containing crude CSL at 20.5 g/kg.
6. Dietary CSL increased egg fat saturation, altering the ratios of stearic to oleic, palmitic to palmitoleic and heptadecanoic to hepta‐decenoic fatty acids.
7. Treatment of CSM with FSH reduced the slight brown yolk discolouration in fresh eggs (experiment 2) and the yolk mottling in warm‐stored eggs. Both in solution and as crystals, FSH prevented the enhancement of brown yolk discolouration in cold‐stored eggs, leaving most eggs with apricot yolk and pink albumen discolourations.
8. Treatment of CSM and CSL with FSH reduced the CPFA‐related effects on yolk fat saturation, and the colour and pH changes in cold‐stored eggs.
9. Exposure of yolks to ammonia vapour provided a useful test to predict the development of the gossypol‐related brown discolouration in stored eggs. 相似文献
2. Supplementation with hesperidin did not affect egg production, egg weight and egg quality traits.
3. No hesperidin effect on yolk and plasma cholesterol was observed. A strain effect was found with lower total and per g yolk cholesterol of brown hens in comparison to the white ones.
4. Oxidative stability of egg yolk, expressed as ng MDA/g yolk, was significantly improved in the hesperidin groups even from the first week of supplementation. At the same time, a significant improvement in the oxidative stability of egg yolk due to the incorporation of hesperidin in hens’ diet was observed after 30 and 90 d of storage at 20°C and 4°C, respectively.
5. No hesperidin by strain interaction was detected for any of the traits measured.
6. In conclusion, incorporation of hesperidin to laying hens’ feed did not affect productive and egg qualitative traits. On the other hand, dietary hesperidin supplementation significantly improved oxidative stability of both fresh and stored eggs. Antioxidant properties of hesperidin seem to make it a promising natural agent for improving the shelf life of eggs. 相似文献
2. Egg, yolk, albumen and shell plus membrane weights increased, whereas the egg shape, specific gravity and shell thickness decreased between 49 and 154 days of age.
3. Yolk, albumen and shell plus membrane comprised 32–59%, 53–57% and 7–80%, respectively of the total egg weight.
4. Regression between the quail's age and the characteristics of eggs were derived and correlation coefficients ranged from —0–42 to — 0–86. The albumen weight was more highly correlated with egg weight than yolk weight.
5. Relationships were also derived between egg shape and specific gravity, and egg shape and albumen weight.
6. It was concluded that the eggs’ characteristics were modified as the quails aged, and the best criterion of the shell's strength was the egg shape. 相似文献
2. The application of the 28‐h cycle did not affect mean rate of lay but increased mean egg weight and egg output.
3. Grouping the birds according to their preliminary sequence length yielded an interesting outcome. In both rooms, birds with short sequences (≤ 6 eggs) produced significantly more eggs under the 28‐h cycle, while those with long sequences (> 6 eggs) produced marginally fewer eggs. The same trend was also evident with egg output.
4. Changing from 24‐h to 28‐h increased yolk and albumen weights as well as shell quality. However, relative to egg weight, no measurable effect was detected due to light cycle, age or sequence length on yolk and albumen weights.
5. The paper provides new evidence suggesting that long ahemeral cycles could be used to improve egg production as well as shell thickness in flocks with modest rates of lay. 相似文献
2. There was considerable variation between individuals in the mineral concentration in their eggs (coefficients of variation ranged between 3.8% for sodium to 19.9% for calcium in the albumen, and between 4.3% for phosphorus to 11.8% for iron in the yolk).
3. At the same time, the moderately high repeatability of mineral concentration (t = 0.4?0.6) in successive eggs from the the same hen for several of the minerals analysed is indicative of some positive control by the hen of the mineral composition of her eggs.
4. There was a highly significant correlation (P≤ 0.001) between the mean concentration of potassium in the albumen and the hatchability of the eggs, supporting the claim that a deficiency of potassium in the egg could be the basis of some failures in hatchability.
5. The study also revealed variation among individual birds in the concentration of iron in the yolk which was negatively correlated (P≤0.01) with hatchability. No clear basis could be suggested for this variation among individual birds. 相似文献
2. Seventy-two White Leghorn laying hens (58-week-old; three per cage) were randomly allotted to one of four dietary treatments: 0%, 7.5%, 15.0% and 22.5% of EF-supplemented diets for 8 weeks.
3. Supplementation with EF had no effect on feed intake, egg production, feed conversion ratio and egg weight. Egg components (yolk, albumen and shell percentages) were similar among treatments, except that shell percentage was greater for layers fed 22.5% EF than those fed 7.5% and 15% EF. The ATTR of dry matter and organic matter were highest for 0% and 7.5% EF, intermediate for 15% EF and lowest for 22.5% EF. Similar reductions on ATTR of crude protein and nitrogen-corrected apparent metabolisable energy were observed for layers fed 22.5% EF relative to those fed 0% or 7.5% EF.
4. Feeding EF at 7.5%, 15.0% and 22.5% of the diet markedly increased (by 92%, 198% and 271%, respectively) egg yolk concentrations of n-3 polyunsaturated fatty acid (PUFA) and reduced saturated fatty acid and n-6 PUFA concentrations.
5. It was concluded that omega-3 labelled eggs (300 mg/60 g of egg) may be produced with low (7.5% of diet) levels of dietary EF without compromising egg production parameters. However, feeding moderate to high levels of EF (i.e. 15% and 22.5% EF) may reduce total tract nutrient and energy utilisation. 相似文献
2. Eggs with extremely low, average and extremely high yolk ratio were chosen for further investigation (n = 350 in each group in both genotypes). After incubating the selected eggs, hatched birds were reared and slaughtered at 11 weeks of age.
3. The yolk ratio of eggs significantly affected the body composition of the chickens at hatching and during rearing to 8–9 weeks of age.
4. Chickens of a genotype selected partly for weight gain had significantly higher live weight from hatching to the end of the rearing period and had better slaughter characteristics than those of the dual purpose TETRA-H genotype.
5. At hatching, only the dry matter content of the body was affected by the gender of the birds. The effect of gender on the live weight and body composition of chickens was evident from the 5th week of age to the time of slaughter.
6. It was concluded that eggs with a low yolk ratio were most beneficial for broiler production, because chickens hatched from these eggs had the highest slaughter weight and muscle index and the lowest fat index for their body mass. 相似文献
2. The yolk: albumen ratio of the goose egg was higher.
3. The fat concentration in the egg yolk and the protein concentration in the egg albumen were lower.
4. Deposition of dry matter in the embryo and energy expenditure during incubation were similar. In both species, the nitrogen in the embryo exceeded the nitrogen in the egg contents. This is probably due to the utilisation of egg‐shell membrane proteins.
5. Lysine concentration in the goose egg proteins was lower, which was reflected in the hatched gosling proteins.
6. There were high correlations in amino acid concentrations between chicken and goose eggs and between the efficiencies of amino acid utilisation by their embryos, implying that similar metabolic processes are involved in these two species. 相似文献
2. Yolk weight is related to hen age and may be predicted using a linear-by-linear function, the coefficients of which are the same for Cobb and Ross breeders. Allometric functions may be used to predict albumen weight from yolk weight, and shell weight from the weight of the egg contents. Egg weight is given by the sum of the three components.
3. The proportion of yolk increased with advancing age whilst the proportions of albumen and shell decreased. However, at a given age, larger eggs contain proportionally more albumen. Eggs from Cobb hens had proportionately more albumen than Ross eggs towards the end of lay.
4. A stochastic population model verified that these functions accurately reflect the proportional changes in the egg components with advancing hen age and at a given age, over a range of egg weights. 相似文献
2. A total of 360 Beijing PINK-1 laying hens (60 weeks old) were randomly distributed among five dietary treatments, each of which included 6 replicates of 12 hens. Dietary treatments were basal diet supplemented with 0 (control), 0.5, 1.0, 2.0 and 4.0 g/kg diet resveratrol. The study lasted for 9 weeks including 1 week of adaptation and 8 weeks of the main experimental period.
3. The results indicated that dietary resveratrol significantly improved feed conversion ratios during 5–8 weeks and 1–8 weeks of the trial. Increasing dietary concentrations of the resveratrol linearly improved Haugh unit and albumen height of eggs.
4. The content of total cholesterol (TC), total triglyceride (TG), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C) in serum and cholesterol in yolk was significantly decreased by dietary resveratrol, and there were significant linear correlations between these indexes and resveratrol supplemental levels.
5. Dietary resveratrol supplementation significantly improved serum Glutathione peroxidase (GSH-Px) enzyme activity and decreased serum malondialdehyde (MDA) content in groups with 2.0 and 4.0 g/kg resveratrol as compared to the control, respectively. However, supplementation of resveratrol did not affect the activity of serum superoxide dismutase (SOD).
6. It is concluded that resveratrol supplementation has a positive effect on performance, lipid-related traits and antioxidant activity of laying hens. 相似文献
The heritability figure of 0.50 for egg weight agrees with the majority of those in the literature. The larger value of 0.71 derived from the sire component compared with that from the dam component of 0.29 is in agreement with a number of other reports suggesting the existence of sex linkage.
The heritability of yolk weight was estimated to be 0.43 with no difference between estimates derived from sire and dam components. Attention is drawn to the lower precision of the figures based on dam components because of the small number of daughters per dam available.
Correlations between egg weight and yolk weight are high. The phenotypic correlation is 0.58 and the genetic correlation 0.82, whereas the environmental correlation is only 0.33.
Continuing selection for increased egg weight is therefore expected to lead to a concomitant increase in yolk weight nearly as great as that expected from direct selection for yolk weight.
The heritability of the yolk weight/egg weight ratio is low, of the order of 0.20. The negative phenotypic correlation of —0.42 of this ratio with egg weight is the joint effect of a large negative genetic correlation of — 1.00 and a small positive environmental one (0.02). Direct selection for a higher yolk ratio would therefore be tantamount to selecting for small eggs. 相似文献
2. Eggs incubated at 36.5°C hatched later than eggs incubated at 37.5°C but did not differ in age of mortality or incidence of malpositions and abnormalities.
3. Eggs incubated at 38.5°C hatched significantly less well than eggs incubated at 37.5°C and showed significant differences in time of embryo mortality. Overheated embryos had a mortality peak between 15 and 20 d of incubation and an increased mortality after 24 d of incubation.
4. Overheated eggs were characterised by a high incidence of embryos with head in small end, with excess albumen, ruptured yolk sacs, oedematous heads, eye cataracts and swollen down‐plumules. 相似文献
2. Changes in the body composition of the hens were followed in vivo by means of computed tomography (CT) four-weekly, between 20 and 72 weeks of age. The measurements covered the whole body of the hens using overlapping 10 mm slice thicknesses on a Siemens Somatom Emotion 6 multislice CT scanner.
3. The yolk, albumen and shell ratio of the eggs, produced on the days of the CT measurements by the hens, were determined and their composition was analysed chemically.
4. The body fat content of the hens increased continuously until 44 weeks of age and plateaued thereafter in both genotypes. However, the body fat content of the white egg layers was always higher than that of the brown egg layers.
5. The yolk ratio and the dry matter and crude fat content of the eggs of white egg layers were higher than the brown egg layers throughout the experiment.
6. Moderate correlations were observed in both genotypes between the body fat content of the hens and egg yolk ratio of their eggs. 相似文献
2. Heritability estimate for yolk weight was 0.5 ± 0.1; for albumen percentage protein, 0.6 ± 0.1; and for yolk percentage solids, 0.5 ± 0.1.
3. Genetic correlation estimates indicated that there was no antagonistic relationship between the weight of any egg component and its composition but, because of the unreliability of the estimates of the genetic correlations involving the egg number traits, it is impossible to predict the correlated effects that selection for egg composition would have on egg number.
4. Eggs from selected strains weighed an average of 3‐. g more, contained more albumen, and greater amounts of albumen percentage solids and percentage protein than controls, whereas no differences were found for yolk weight; yolk percentage solids changed little in the selected strains.
5. Comparisons of one control strain with four commercial strains suggest that the findings may be applicable to commercial stocks. 相似文献
2. A total of 160 Hy-Line Brown layers (45 weeks old) were randomly assigned into 4 treatments on the basis of laying performance. Each treatment had 4 replicates with 10 birds each.
3. Dietary treatments were basal diet supplemented with 0 (control), 2.5, 5.0 and 7.5 g/kg diet G. procumbens during 56-d feeding period.
4. Serum (d 21, 42 and 56) and egg yolk (d 28, 42 and 56) cholesterol and triglycerides concentrations were linearly reduced with increasing dietary concentrations of G. procumbens.
5. Increasing dietary concentrations of G. procumbens linearly reduced the excreta total anaerobic bacteria (d 28), Clostridium sp. and Escherichia coli (d 28 and 56) populations.
6. Overall egg production and egg mass were linearly increased, and overall feed efficiency was linearly improved with increase in dietary G. procumbens.
7. Dietary increasing concentrations of G. procumbens linearly improved egg yolk colour (d 28 and 56) and breaking strength of eggs (d 56).
8. The results obtained in the present experiment indicate that dietary supplementation with G. procumbens could reduce the egg yolk cholesterol, suppresses harmful excreta microflora and improves layers performance. 相似文献