Quality characteristics of quail eggs

1. An experiment was carried out with laying Japanese quail to study the influence of age on their egg quality.

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.     

Differences in egg‐shell quality among the Sinai Bedouin fowl,the commercial white leghorn and their crossbreds

1. A comparison of egg‐shell characteristics was made among the Sinai breed (a desert inhabiting strain), the commercial White Leghorn and their reciprocal crossbreds.

2. The Sinai egg was smaller and its shell thicker and stronger than the Leghorn egg. All the differences were statistically significant.

3. Shell thickness and strength of Leghorn eggs were in accordance with values predicted on the basis of egg mass, while those of the Sinai and the two crosses were considerably higher than predicted.

4. The apparent differences in mean egg mass between Sinai and Leghorn breeds did not explain the differences in egg‐shell quality, neither did the shape index which was very similar among all breeds.

5. The findings suggest that the differences in egg‐shell properties are of a genetic origin.

6. The thick, strong and less permeable egg‐shell of the Sinai breed may reflect adaptations to its arid environmental origin and to incubation in the open.

7. These genetically‐determined egg‐shell characteristics might serve in a future selection for improved egg‐shell quality in poultry.     

Comparison of changes in production and egg composition in relation to in vivo estimates of body weight and composition of brown and white egg layers during the first egg-laying period

1. The aim of this study was to compare the changes in the production and in the body and egg composition of 45 TETRA SL brown egg layers and 45 TETRA BLANCA white egg layers during the first egg-laying period.

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.     

Cross performance as influenced by selection in pure lines

1. The resultant genetic gains in cross performance due to the individual, dam family and sire family (IDS) method of index selection for increased part‐period egg number in their parent lines are described.

2. A randombred control population of known pedigree was used to measure the environmental trends.

3. Selection in pure lines resulted in concomitant improvement in the crosses for the selected as well as the correlated traits.

4. Cross performance was comparatively more than expected on the basis of mid‐parent values, indicating involvement of non‐additive gene action in the expression of cross performance.

5. Crosses responded better to independent culling level selection for egg weight than their parents.

6. Heterosis appeared to increase in later generations as compared with initial generations of selection.     

Asociation of plasma 5'‐nucleotidase and alkaline phosphatase with production traits in chickens: Effects of age and housing systems

1. The housing system, age of pullets and their interaction had a significant effect on plasma 5'‐nucleotidase and alkaline phosphatase activities.

2. Activities were higher in birds in cages than in those on the floor, reflecting perhaps the stress of caging. Activities increased with age.

3. Activities were higher in pullets selected for higher production.

4. The type of housing had no effect on egg production, but age at first egg, egg weight and 40‐week body weight were found to be affected significantly.     

Evaluation of bone strength,keel bone status,plumage condition and egg quality of two layer lines kept in small group housing systems

1. The aim of the present study was to determine the influence of large (54 or 60) and small (36 or 40) group sizes and tiers of the small group housing system “Eurovent German” on tibia and humerus bone breaking strength, keel bone status, plumage condition and egg quality for two commercial layer lines, Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB), at the same stocking density (890 or 830 cm²/bird).

2. In 4 consecutive trials, 4752 hens were recorded for keel bone status. Evaluation of plumage condition was made for 1440 hens and bone breaking strength was recorded for 1200 hens. A total of 4962 eggs were analysed for internal and external egg quality traits. Analyses involved 30 small group compartments per trial.

3. The layer line had a much more pronounced influence on humerus breaking strength than on tibia breaking strength.

4. Plumage condition, particularly on the neck, was positively correlated with humerus breaking strength in both layer lines.

5. An average of 34% of LB and 23% of LSL hens showed keel bone deformities, with higher proportions of slight deformities.

6. Slight keel bone deformities, rather than moderate to severe, increased significantly during the laying period.

7. Stocking density had no influence on bone breaking strength, keel bone status and egg quality traits.

8. LB layers had a 1.4-fold higher humerus, but only a 1.06-fold higher tibia breaking strength compared to LSL layers.

9. Tibia breaking strength was significantly affected by the interaction of group size and layer line. LSL layers in small groups had lower tibia breaking strengths than those of the large groups.     

Selection for high specific gravity of eggs in a flock of Australorp hens

1. A realised heritability of 0.23 was obtained in an Australorp flock (S) selected for five generations for high egg specific gravity.

2. A comparison with an unselected control flock (C) over 50 weeks of lay in the final generation indicated a number of statistically significant correlated responses in commercially important traits in the S line in addition to the direct response of + 0.004 in specific gravity.

3. With an increase in specific gravity, there was a decrease of 3.4 in the percentage of soft‐shelled eggs laid.

4. The weight and albumen height of eggs measured within 1 hour of lay declined by 1.8 g and 2.1 Haugh units respectively.

5. There were reductions in the weight and albumen height losses of eggs stored over a 10‐d period (C 0.74, S 0.62 g and C 17.9, S 15.0 Haugh units respectively), so that at the end of this period the albumen heights in both lines were the same.

6. Average body weight and daily food intake were less by 0.28 kg and 7.5 g respectively.

7. Although there was no change in egg production, the average age at first egg was reduced by 11.3 d.     

The utilisation of goose egg nutrients by the developing embryo

1. Eggs and hatched embryos from geese were analysed for their proximate and amino acid composition. In comparison with eggs and embryos of the domestic fowl the following were found.

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.     

Comparison of the productive perform. Ances of the Sinai Bedouin fowl,the white leghorn and their crossbreds: Study under laboratory conditions

1. A comparison of the productive performances of the Sinai Bedouin fowl (from the Sinai desert), the commercial White Leghorn and their reciprocal crossbreds was made under uniform normal conditions.

2. The Sinai produced significantly fewer, smaller eggs, resulting in lower egg mass output (g/bird d), than the Leghorn and the crossbreds.

3. Egg weight of both crossbreds was intermediate between Sinai and Leghorn but laying rate was closer to that of the Leghorn.

4. Differences in egg mass output apparent at 8 to 10 months of age decreased considerably with age.

5. These findings suggest that selection or crossbreeding of the Sinai might improve productive performance while maintaining improved eggshell quality.     

Egg‐shell water Vapour conductance of the domestic fowl: Comparison between two breeds and their crosses

1. A comparison of egg water loss and egg‐shell water vapour conductance was made between the Sinai fowl (a desert inhabiting breed) and the commercial White Leghorn, together with their reciprocal crossbreds.

2. The Sinai egg was found to be smaller and less permeable to water vapour than the eggs of the Leghorn and crossbreds. The differences were statistically significant.

3. The measured egg‐shell water vapour conductance of the Sinai breed was 25% lower than predicted on the basis of egg mass.

4. The low permeability of the Sinai egg shell might be related to its higher than predicted thickness, which did not interfere with the shell functional pore area.

5. The low water vapour conductance of the Sinai egg shell may reflect adaptations to its dry habitat.     

The effect on profit of Optimising nutrient density for laying hens

1. Using economic data from three locations in Australia nutrient densities were compared in laying diets which either minimised the daily cost of feeding a hen or maximised profit.

2. The effects of nutrient density on rate of production and egg weight were examined using published data to show that, within the range chosen for the analysis, nutrient density did not significantly (P < 0#lb05) affect rate of lay but was significantly and positively correlated (P< 0#lb01) with egg weight.

3. Nutrient densities which maximised profit were higher than those which minimised daily food cost.

4. Averaged over the three locations, maximum profit was achieved at a nutrient density of 11#lb80 MJ/kg compared with 11*57 MJ/kg to minimise food cost.

5. Food cost at the most profitable nutrient density was $2#lb00 per tonne higher than at the nutrient density which minimised food cost but resulting profit was slightly higher.     

The effects of feeding regime and stocking rate on the performance of medium‐bodied layers in the humid tropics

1. The effects of housing laying hens 1 or 2 per cage (1 452 or 726 cm² /bird), and three feeding regimes (ad libitum, 70% ad libitum and 6 days/ week) were investigated.

2. With 2 birds/cage egg production and food utilisation were adversely affected, but there were no significant effects on egg weight, food consumption, shell thickness, body‐weight change, mortality and abdominal fat.

3. Food restriction significantly increased body‐weight loss and decreased egg production, food consumption, final body weight and abdominal fat, but had no significant effect on egg weight, shell thickness and mortality. The effect on food utilisation was inconsistent.

4. There were significant interactions between feeding regime and stocking rate for egg weight and final body weight.

5. It is suggested that in the humid tropics birds caged singly could be fed at 70% ad libitum while those caged in pairs should be fed ad libitum to avoid multiple stress.     

The response of egg weight to the inclusion of different amounts of vegetable oil and linoleic acid in the diet of laying hens

1. Four diets containing different amounts of vegetable oil and linoleic acid were fed to White Leghorn hens throughout a full laying year.

2. Egg weight was poor with the low fat basal diet but increased in relation to the amounts of maize oil (4 and 30 g/kg) included in the diet.

3. With a diet containing 30 g olive oil/kg, egg weight was similar to that obtained with the diet containing the same amount of maize oil.

4. Rearing the birds on diets containing low or moderate amounts of linoleic acid did not affect the response to fatty acid content of the layer's diet.

5. It is concluded that the requirement of the laying hen for linoleic add is not higher than 9 g/kg but that egg weight does respond to higher dietary amounts of readily absorbable fatty acids.     

Physical and chemical nature of eggs from six breeds of domestic fowl

1. The physical nature and chemical composition of the eggs from several breeds, White Leghorn, Rhode Island Red, Sussex, Maran, Dwarf Sussex and English Gamecock, have been studied.

2. The water content was highest in White Leghorn eggs, which were the heaviest.

3. Cholesterol content was similar in all eggs except for Dwarf Sussex in which it was less.

4. English Gamecock eggs contained a higher proportion of protein than those of the other breeds.

5. From the data presented, egg size, under similar conditions of feeding, does not determine the contents of components of the egg, but there are underlying genetic factors.     

Effect of hesperidin dietary supplementation on hen performance,egg quality and yolk oxidative stability

1. The purpose of this study was to evaluate the effects of dietary supplementation with hesperidin (one or 3 g/kg of feed) for 31 d on the performance, egg quality and yolk oxidative stability of brown and white laying hens (26-wk old).

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.     

Effect of gradual acclimation to high ambient temperatures on egg‐shell quality of the Sinai Bedouin fowl,the commercial white leghorn and their crossbreds

1. The effect of gradual acclimation to high ambient temperatures on egg‐shell quality was studied in the Sinai fowl, the commercial White Leghorn, and their reciprocal crossbreds.

2. The Leghorn egg was characterised by a thinner and weaker shell compared with the Sinai and the crossbreds, at all the experimental temperatures.

3. In contrast to other reports, high ambient temperatures for a long period had only mild effects on egg‐shell quality.

4. The results suggest that gradual acclimation to high ambient temperatures might improve the efficiency of the physiological mechanisms involved in the hen's response to heat. Consequently, the reproductive process adapts to the hot environmental conditions.

5. The results indicate that the Sinai breed might be used for future selection of a breed, highly resistant to extreme environmental conditions and with an improved shell quality.     

Physical characteristics of intact and cracked eggs

1. Six egg samples, comprising equal numbers of intact and cracked eggs, were collected from three flocks of hybrid layers.

2. Cracks were classified according to type (hole, star or straight) and the weight, shape, shell colour and specific gravity of all the eggs were measured. Shell thickness and dry shell weight were also recorded for a maximum of 10 intact and 10 cracked eggs from each sample.

3. The largest proportion of cracks were holes.

4. Differences in mean egg weight and shape of intact and cracked eggs within each sample were inconsistent. Mean shell colour was darker for the intact brown eggs than for the cracked ones. For all the samples, mean egg specific gravity, shell thickness and dry shell weight were higher for the intact eggs. The difference in egg specific gravity was significant (P<0.05) for all samples.

5. Holes occurred in eggs of lower mean weight but with better quality shells than those in which star or straight cracks occurred.     

Effect of dietary supplementation of bacteriophage on performance,egg quality and caecal bacterial populations in laying hens

1. Bacteriophages (BP) have gained increasing attention as a treatment of bacterial infection for animals. However, the data pertaining to dietary application of BP for laying hens have been limited.

2. This study aimed to investigate the effect of dietary BP on laying performance, egg quality and caecal bacterial populations in laying hens.

3. The dietary BP used in this experiment was a mixture of individual BP targeting Salmonella gallinarum, Salmonella pullorum, Salmonella typhimurium, Salmonella enteritidis, Salmonella derby and Staphylococcus aureus.

4. A total of 360 Hy-Line Brown laying hens of 32 weeks of age were allotted to one of three dietary treatments with 6 replicates in a completely randomised design. The basal diet was prepared, and 0.4 or 0.8 g/kg BP mixture was supplemented to the basal diet. Diets were fed to hens for 8 weeks.

5. Laying performance and egg quality were not affected by dietary treatments. As inclusion levels of BP mixture in diets were increased, the DNA copy numbers for Salmonella spp. in the caecal contents decreased linearly, whereas the DNA copy numbers for Escherichia coli in the caecal contents increased linearly.

6. Results indicate that dietary supplementation of BP mixture decreases the target Salmonella spp. populations but increases Escherichia coli populations in the gastrointestinal tract of laying hens with little impact on laying performance and egg quality.     

A mathematical representation of the Ovulatory cycle of the domestic hen

1. The ovulatory cycle of the domestic hen (Gallus domesticus) was postulated to be the result of the interaction of two independent systems.

2. A circadian system was postulated to control the restriction of ovulation to an 8‐h period of the day under conventional 14 h light: 10 h dark regimes.

3. The final phase of follicular maturation was postulated to commence after ovulation of the preceding ovum in the hierarchy.

4. Ovulation was postulated to occur when a mature follicle was present in the ovary during the appropriate phase of the circadian‐linked system.

5. The predicted times of oviposition were within the standard error of the observed times of oviposition under 21‐, 24‐ and 28‐h photoschedules.

6. It was concluded that this hypothesis for the control of the ovulatory cycle of the hen is consistent with current knowledge.     

Energy requirement of laying japanese quail

1. Two feeding experiments were conducted to determine the meta‐bolisable energy (ME) requirement of laying Japanese quail. Birds were fed to provide 5.5 g protein and 167, 209, 251 or 293 kJ ME/d.

2. As ME intake increased from 167 to 293 kJ egg production increased.

3. Quadratic relationships between ME intake and egg production, ME intake and egg weight, and ME intake and egg mass (g egg/ bird d) were derived and used to determine the energy required for an acceptable production rate.

4. To maintain a production of 8.3 g egg/bird d (90 eggs/100 bird d with a mean weight of 9.3 g) required 260 kJ ME/bird d.