Traits influencing the hatching performance of Japanese quail eggs

1. Japanese quail eggs from moderately heavier sires showed superior fertility; while fertile eggs from moderately heavier dams hatched slightly better than the eggs from lighter dams.

2. Higher rates of fertility and hatchability of Japanese quail eggs were observed from parents of 10 to 19 weeks of age, with peak fertility and hatchability at 14 and 12 weeks of age, respectively.

3. Sex ratios of 1:2 to 1:5 gave comparable fertility and hatchability results.

4. The hatching performance of quail eggs from cage and deep litter reared breeders was comparable.

5. Fertility and hatchability were directly proportional to the egg weight.

6. Quail egg shell colour, tints and blotches were found to influence hatching performance.

7. Storing quail eggs at 16 ± 2°C and 75 ± 5% relative humidity for more than 4 d reduced hatchability.

8. Hatchability of eggs stored at room temperature was improved if they were sealed in polyethylene bags.

9. Provision of light during the first 14 d of incubation resulted in a photo‐acceleration of about 3.2 h.     

Influence of pre‐incubation treatment on hatching results of broiler breeder eggs produced at 37 and 59 weeks of age

1. The influence of temperature in the nest box, temperature during storage, storage time and pre‐setting temperature on the hatchability of broiler breeder eggs produced by birds of 37 and 59 weeks of age was examined.

2. All treatments that can be characterised as being less optimal for embryo survival than the control treatment affected the hatchability of fertile eggs more in the case of eggs produced by older birds.

3. A higher temperature in the nest box, longer storage periods, higher storage temperature, especially at longer storage periods, and higher pre‐setting temperature significantly reduced the hatchability of fertile eggs from the older birds.

4. For the younger birds, a significant reduction of hatchability was found only for the longest storage period.     

Divergent selection for shape of growth curve in Japanese quail. 7. Effect of egg storage at high temperature on embryo development and hatchability

1. Hatching time, hatchability of fertile eggs and embryo mortality in relation to (1) physical quality of fresh eggs and (2) embryonic development during storage and incubation periods were analysed after egg storage for 1, 5 or 10 d at 30°C in the meat-type lines of Japanese quail, HG and LG, divergently selected for high and low relative weight gain between 11 and 28 d of age, respectively, and constant body weight at 49 d of age.

2. In both lines, the increase of egg storage temperature from 12°C (standard level) to 30°C increased the egg weight loss during storage, shortened the incubation period and reduced the hatching success.

3. Similar to standard egg storage temperature, LG quail hatched earlier than HG quail after egg storage at 30°C and early and late mortality of both lines increased with a prolonged period of egg storage. In contrast to the standard egg storage conditions, no line differences in hatchability were observed.

4. The results did not identify a relationship between the decrease in hatchability or embryo viability and line differences in external egg parameters as well as any important role of undesirable changes induced by a high storage temperature on albumen viscosity.

5. The pattern of embryonic death, low developmental rate of embryos and a dichotomy between the development of the extra-embryonic vascular system and the embryo itself during egg storage at high temperature implied that an insufficient nutrient supply in consequence of developmental delay could represent a key factor in increasing early and late embryo mortality.     

Factors affecting the hatchability of eggs from broiler breeders

1. Four experiments were carried out on eggs from broiler breeding flocks between 26 and 60 weeks of age. The effects of storage and incubation conditions on hatchability were tested.

2. Collecting eggs hourly rather than five hours after lay slightly reduced hatchability (P<0.10). Pre‐storage fumigation of almost un‐contaminated eggs had no effect on hatchability even after storage for 8 d. Storing eggs in unsealed polythene bags did not affect hatchability of eggs stored for 5 or 8 d.

3. Eggs stored for 2 d hatched better when held at 18 °C than at 15 °C (P<0.05). Eggs stored for 8 d at 15 °C hatched better than eggs stored for 8 d at 18 °C (P< 0.01). Best hatchability was in eggs stored in unsealed polythene bags at a room temperature of 15 °C. When older eggs were allowed 30 to 40 min more in the setter for each day of storage, the decline in hatchability was 0.5 to 0.6 percentage units per day in storage as compared with a decline of 1.2 percentage units per day when eggs of different storage times, up to 8 d, were set simultaneously.

4. Those eggs which showed a weight loss during incubation of near average for their relative humidity (RH) treatment tended to hatch better than others except under conditions of very low RH (0.36), when best hatchability was associated with lower than average weight loss.

5. In eggs from a young flock (28 to 44 weeks of age) hatchability of fertile eggs was depressed by 1 percentage unit with an increase in RH of 0.17, and by 1 percentage unit with each decrease of 0.06 in RH from a control RH of 0.53. In eggs from the same flock between 48 and 60 weeks of age hatchability was depressed by 1 percentage unit with each 0.037 increase in RH from 0.44 to 0.70.

6. Eggs from a young flock (34–49 weeks) hatched significantly better when maintained at 0.82 rather than at 0.66 (P<0.05) or 0.95 (P<0.10) RH during the hatching period from 19 to 21 d of incubation. Eggs from an older flock (51–61 weeks) hatched better at 0.82 and at 0.‐92 than at 0.72 RH during the same period, but the differences were not significant.     

Microbial spoilage of ostrich (struthio catnelus) eggs

1. The incidence of microbial spoilage was investigated in three batches of ostrich eggs, one from Africa and two from Europe.

2. 18% to 21% of eggs in each batch were contaminated with bacteria and fungi, with the latter being found more often in eggs which contained more advanced embryos.

3. Although infertility and prolonged storage reduced hatchability, the high inci dence of microbial contamination in ostrich eggs is deemed to be a significant problem.

4. Improving nest hygiene is considered to be the simplest way to reduce microbial spoilage.     

Effects of storage conditions on hatchability of chicken eggs in a warm climate

1. A total of 3792 eggs from AF Bosbek layer parents were used to determine the effect of storage time on the hatchability of eggs kept either small end up (SEU) or small end down (SED).

2. These eggs were stored at room temperature (27°C‐31°C) or in an air‐conditioned room (20°C‐23°C), for two, three, six or seven days and incubated in four replicate hatches.

3. Eggs kept SEU improved hatchability even for short‐term storage when temperatures were high.

4. Simple air‐conditioning can reduce the temperature sufficiently for the viability of the embryo to be preserved for up to a week.     

Increasing hatchability of turkey eggs by injecting eggs with pyridoxine

1. In field trials, eggs from two flocks of Large White turkey hens were injected with about 0.2 ml saline solution containing 600 μg of pyridoxine hydrochloride in order to examine its effect on hatchability.

2. Also, in an aseptic laboratory trial, eggs from Large White turkey hens were injected with 0.2 ml of saline solution and 0.2 ml of saline solution containing 600 μg of pyridoxine hydrocholoride.

3. In field trials, hatchability of pyridoxine‐injected eggs was 4.6% higher (P<0.05) than the control (non‐injected) eggs.

4. In the aseptic laboratory trial, hatchability of pyridoxine‐injected eggs was 4.2% higher (P<0.05) than saline‐injected and control (non‐injected) eggs.     

Genetic inferences from inter‐strain crossing for hatchability and fertility in white leghorns

1. Heritability estimates for hatchability of fertilised eggs were obtained from four White Leghorn strains and their crosses.

2. Based on the variance of the full‐sib family means, the heritability estimates for pure‐bred, cross‐bred and for the combined data were 0.lb186 ± 0.lb105, 0.lb065 + 0.lb021 and 0.lb088 + 0.lb005, respectively: the results showed absence of non‐additive genetic variance for hatchability.

3. Fertility was influenced more by sire strain than by the dam while hatchability was primarily influenced by the dam strain.

4. The sire x dam interaction effect was significant for fertility but not for hatchability.

5. Fertility was influenced by crossing two divergent strains.     

Effect of egg composition on hatchability and on growth and slaughter characteristics of meat-type chicks

1.?Using the so-called TOBEC (Total Body Electrical Conductivity) method, which allows the determination of egg composition in vivo, correlations between egg composition, hatchability and hatched chicks’ development were studied.

2.?A total of 1500 hen eggs (Ross-308) were measured by TOBEC, and eggs with extremely high (10%, n = 150), extremely low (10%, n = 150) and average (10%, n = 150) electrical conductivity values were chosen for further investigation.

3.?During the incubation period, it was observed that eggs with high electrical conductivity had a significantly higher mortality than eggs with low electrical conductivity.

4.?It was observed that both the increase in electrical conductivity at the same egg weight, and the increase in egg weight at the same electrical conductivity resulted in an increase in the hatching weight.

5.?It was found that the dry matter, protein and fat content of the chicks hatched from eggs with low electrical conductivity was higher at hatching than that of the chicks hatched from eggs with high electrical conductivity.

6.?At 42 d of age the liveweight of cocks and pullets hatched from eggs with low electrical conductivity was 3·2 and 8·2% higher than the liveweight of cocks and pullets hatched from eggs with high electrical conductivity.

7.?Because of the higher liveweight at slaughter, there was a significant superiority of the chicks hatched from eggs with low electrical conductivity in the case of the examined carcase traits at slaughter.

8.?Similar tendencies were found also in the ratios of carcase variables to liveweight, but the between group differences were not statistically significant in this case.

9.?Based on the results it was concluded that TOBEC seems to be a useful method for separating eggs with different composition.

10.?This could be a good starting point for further in vivo investigations in order to clarify the effect of egg composition on hatchability and further development.     

The influence of sample size on the choice of method and interpretation of incubation experiments

1. An equation relating batch size to between‐treatment differences has been adapted for hatchability studies and its implications for research considered.

2. Very large egg batches are required to detect small improvements in the hatchability of good hatching strains.

3. Small‐scale laboratory studies on hatchability are best confined to strains and species of low hatchability in which larger between‐treatment differences may be expected.

4. The results of hatchability studies should always be subjected to tests of statistical significance.

5. There is a strong case for studying continuous variates in the laboratory before proceeding to large‐scale hatchability studies.     

Comparisons of egg quality traits,egg weight loss and hatchability between striped and normal duck eggs

1. The egg quality of striped and normal duck eggs was compared to determine why striped eggs show decreased hatchability. A total of 430 eggs, obtained from a Pekin duck breeder flock aged 50–65 wks, were used in three experiments. The eggs were weighed and assigned randomly to measure egg quality traits, egg weight (EW) loss and hatchability during incubation.

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.     

Storage of hatching eggs: The effect on early embryonic development

1. Embryos of eggs incubated for 42 h after storage for 7 or 14 d were retarded by 5.3 and 12.2 h, respectively, compared with those of non‐stored incubated eggs.

2. This was not due entirely to a delay in the initiation of embryonic development; the rate of development during the first 2 d of incubation was significantly lower in eggs stored for 14 d than in non‐stored eggs.

3. There was no correlation between the developmental age of an embryo after any specified incubation time and either the original weight of the egg or the weight loss during storage.

4. The incidence of dead and malformed embryos increased progressively with the duration of storage.     

Effect of oiling on internal quality of eggs stored at 28 and 12°G

1. The effects of spraying linseed oil on naturally clean eggs, subsequently stored for 24 d at 28 °C were studied.

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.     

Ostrich (Struthio camelus) embryonic development from 7 to 42 days of incubation

1. Hatching success of ostrich eggs is poor (50–60% of fertile eggs). The current study was designed to identify the timing of key stages in the development of the ostrich embryo.

2. Growth of both embryo and wing length during 42 d of incubation was comparable and approximately linear, with a more or less weekly doubling in size up to 35 d of incubation.

3. The embryo eye size increased more rapidly than beak length and reached a maximum of ~16.2 mm by 28 d of incubation, whereas beak length increased continuously until hatching at 42 d.

4. Linear regression equations were derived from morphometric measurements of embryos between 7 and 42 d.

5. Information stemming from these results can be used to estimate the age of dead-in-shell embryos in an attempt to identify timing of incubation problems that potentially result in low hatchability of fertile eggs.     

The relationship between hatching egg weight and subsequent performance of broiler chickens

Small eggs constitute a high proportion of the eggs laid by pullets. The literature shows that chick hatching weight is strongly correlated with egg weight, but evidence on the influence of egg weight on hatchability and subsequent performance of chicks is less certain.

The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship.

A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex.

Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability.

A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes.

Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age.

There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks.

Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality.

The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight.     

Storage of hatching eggs: The effect on total incubation period

1. A time‐lapse photographic technique has been developed which enables routine recording of the hatching times of up to 192 chicken embryos.

2. Storage of eggs for 14 d caused a delay of 134 h in the mean total incubation period.

3. Female embryos hatched about 3 h earlier than males in the non‐stored eggs but there was no difference between the sexes in eggs stored for 14 d.

4. Rate of weight loss during incubation was similar in both non‐stored and stored eggs: there was no relationship between weight loss at 19 d incubation and total incubation period.

5. Hatchability of fertile eggs was 19.5% lower in eggs stored for 14 d and proportionately more embryos died between 4 d and 18 d incubation than in the non‐stored eggs.     

Storage of hatching eggs: The interaction between parental age and early embryonic development

1. Embryos in eggs laid by older birds were developmentally more advanced, both at oviposition and after 24 to 42 h incubation, than those in eggs from younger birds.

2. Storage of eggs caused shrinkage of the blastoderm. The amount of shrinkage tended to decrease with parental age.

3. The developmental age of embryos after 42‐h incubation increased with parental age but was reduced by storage, with embryos in eggs from middle‐aged birds (35 to 40 weeks of age) being least retarded.

4. The rate of development in fresh eggs increased with parental age. Storage reduced the rate of development equally at all flock ages.

5. The number of malformed embryos increased with storage time. After 14‐d storage there were fewer abnormalities in eggs from birds between 31 and 49 weeks of age than in younger or older birds.     

The bacterial flora of unhatched eggs

1. The methods of bacteriological examination of hatchery waste eggs were compared.

2. Using one of these methods a survey was conducted on eggs which had failed to hatch from commercial hatcheries.

3. An assessment of the level of contamination in the eggs examined indicated an average level of contamination of 12.7%.

4. The contaminating flora was composed mainly of Micrococcus sp. and Enterobacteriaceae, with Streptococcus sp., Staphylococcus sp., Bacillus sp. and Pseudomonas sp. present at lower levels.

5. Various interrelationships between contamination and hatchability are discussed.     

Incidence and classification of early embryonic mortality in broiler breeder chickens

1. Unusually high early embryonic mortality (EEM) was observed in hatching eggs from broiler compared with white or brown table‐egg breeders in Atlantic Canada. Broiler breeder EEM in Atlantic Canada was twice the EEM in broiler breeders from other areas of North America.

2. Comparisons of holding temperatures (18 and 30°C) for 24 h after egg collection, in combination with a storage time of 0 or 7 d at 18°C prior to incubation, were made using the criteria: embryo development (stage), and size at 0, 3, 6 and 9 d incubation, EEM, late embryonic mortality (LEM) and hatchability (HAT).

3. Stage of development of embryos, at 0 d incubation, was highest for eggs held for 24 h at 30°C and stored for 7 d. Embryo stage, weight and length at 3, 6 and 9 d incubation were positively correlated.

4. Hatchability of fertile eggs was lowest (66.5%) for eggs held for 24 h at 30°C and stored for 7 d and highest (87.2%) for eggs held for 24 h at 18°C and stored for 0 d. Holding temperature and storage time significantly influenced EEM and LEM.

5. EEM classification differed for strain of breeder. In broiler breeders the majority of the EEM was at a relatively late stage of development (exhibiting an obvious blood ring with a visible embryo). In comparison, EEM from table egg breeders was distributed equally among three categories.