Factors affecting hatchability during commercial incubation of Ostrich (Struthio camelus) eggs

1. A batch of 320 ostrich eggs from 9 different farms in Zimbabwe were incubated in a single stage operation and the fate of each was recorded.

2. Hatchability was only 37.2% and the result of high rates of infertility and contamination (22.2% and 22.8% respectively); it varied between eggs from different farms.

3. Embryonic mortality was high at the start and end of incubation, a pattern similar to that of other domestic birds.

4. Mortality of late stage embryos was related to percentage water loss and mass specific water vapour conductance of the shell, with extremes of the ranges causing the highest mortality.

5. Microbial contamination of the eggs was a significant problem and varied in eggs from different farms indicating that more attention is needed in both breeder bird and nest management.     

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.     

The hatching sequence of Ostrich (Struthio camelus) embryos with notes on development as observed by candling

1. The hatching sequence of the ostrich (Struthio camelus) was determined by observing embryos during candling, those in the process of hatching and in dead‐in‐shell eggs.

2. Candling showed that there was a progressive increase in dark shadowing within the egg but fine details were not easily seen. Nevertheless candling is considered to be an important method of assessing development of ostrich eggs during incubation.

3. The ostrich embryo adopts a hatching position and follows a hatching sequence different from that of the fowl. During internal pipping, the air space is pulled towards the beak in the former but the beak moves to the air space in the latter. The right foot has an important role in breaking the shell during hatching.

4. The hatching process is considered to reflect an adaptation to the egg having a hard, brittle shell.

5. Malpositions in the ostrich may have been misinterpreted in the past because of the unusual hatching position. The commonest malposition described here was head‐in‐the‐small‐end.     

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.     

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.     

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.     

Defective egg production in a population of dwarf white leghorns 1

1. The incidence of defective eggs during the first 60 weeks of age increased with time due to significant increases in broken and membranous eggs in a population of dwarf White Leghorn hens.

2. The production of double‐yolked eggs/100 hen d, high during the initial weeks of lay, rapidly declined and disappeared by 30 weeks of age.

3. The frequencies of broken, membranous and soft‐shelled eggs were significantly correlated with each other and with the frequency of multiple daily ovulations indicating a common aetiology for these defective egg types.

4. Double‐yolked eggs were produced by the heavier, earlier‐maturing pullets in the population.

5. Normal egg production in dwarf White Leghorns may be enhanced by reducing the incidence of defective eggs.     

The effect of delaying the onset of laying in pullets with a low‐calcium diet on subsequent egg production

1. A low‐calcium diet (0.5 g calcium/kg) was used to prevent the onset of laying in young pullets.

2. It was fed at 16 weeks of age to five separate groups (groups 2 to 6) each of 50 to 60 birds.

3. Group 2 was fed on a normal layers’ diet at 23 weeks of age, group 3 at 27 weeks, group 4 at 31 weeks, group 5 at 35 weeks and group 6 at 55 weeks while the control group (group 1) of similar size to groups 2 to 6 was subjected to a normal commercial treatment for laying stock.

4. In all the experimental groups the onset of sexual maturity occurred normally, but only one or two eggs were laid before laying ceased under the influence of the treatment.

5. Laying re‐started when the hens were fed on a normal diet and production rapidly rose to a high level.

6. Groups 1, 2 and 3 differed little in the total number of eggs produced up to 72 weeks of age.

7. In all experimental groups there were fewer very small, small and medium eggs than in the control group.

8. It is suggested that the use of a low‐calcium diet before the onset of lay may have advantages which could be exploited on a commercial scale.     

Comparisons of frequencies and egg shell characteristics of broken and intact eggs within diverse populations of chickens

1. Differences were found among eight populations of White Plymouth Rock pullets in the frequency of broken eggs.

2. The shells of such eggs were thinner than those of intact eggs in seven of the populations.

3. The number of defective eggs, the specific gravity of the eggs, and the percentage hen‐day egg production of normal eggs were significantly correlated within populations with the incidence of broken eggs.

4. No significant correlations were found within populations between the incidence of egg breakage and either egg weight, body weight, or shank length.     

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.     

Dietary rapeseed meal and the incidence of tainted eggs

1. Incorporating 0, 3, 6 or 9% rapeseed meal in the diet of brown‐egg laying birds for 28 d resulted in the production of 0, 1.2, 19.3 and 20.9% tainted eggs respectively, the first tainted eggs being laid on the fifth day.

2. During the second and third weeks the incidence of tainted eggs exceeded 20% but fell to 11.4% during the final week.

3. Omission of the rapeseed meal from the diets halted the production of tainted eggs.

4. Neither egg production nor the health of the birds was adversely affected by the treatments.

5. The taint was described as “ fishy ” or “ crabby ” and was distinctive, but the source was not identified.     

Factors affecting the variability in cracked and dirty eggs and egg production profitability on an integrated poultry operation

1. A number of factors causing variability in the percentages of cracked, and dirty eggs and weekly standard margin (WSM) of returns from eggs over production costs were examined on an integrated commercial poultry plant in Scotland.

2. As the bird aged, the percentage of cracked eggs increased (P <0.01) and the percentage of grade A eggs and WSM decreased (P <0.01). Cracks in dirty eggs (10.1%) were more than double those in all eggs laid (4.9%).

3. Seasonal effects on percentage cracked eggs and percentage grade A eggs were one‐third the magnitude of those due to age but were significant (P <0.05).

4. Variability in percentage cracked eggs, dirty eggs and WSM accounted for by the factors measured, were 72, 64 and 92% respectively.

5. The variability in WSM was significantly affected by percentage lay, food consumption and age but not by percentage cracked eggs, originally dirty and grade A eggs.

6. Flock management and climate inside the laying house each increased the amount of variability accounted for in the percentage cracked eggs and dirty eggs by at least 10%.     

Time budget and colour preferences (with specific reference to feeding) of ostrich (struthio camelus) chicks in captivity

1. Time budget analysis of the typical behaviours of young ostrich chicks showed that chicks spent over 50% of their time foraging and walking.

2. Food presented in bowls was largely ignored whereas food scattered on the floor was readily taken.

3. A colour preference test showed that green was the preferred colour.

3 Reprint requests to Dr Deeming at Hangland Farm Ostriches Ltd, Upper Wardington, Banbury, Oxon OX 17 1SU, England     

The effect of time of lay on fertility and hatchability

1. Eggs from an egg‐type breeding flock were collected at 08.00, 11.00, 14.00 and 17.00 h each day.

2. Eggs laid between 05.00 and 11.00 h had higher fertility than eggs laid between 11.00 and 17.00 h.

3. Hatchability of fertile eggs was highest in eggs laid between 05.00 and 08.00 h. Hatchability decreased progressively for eggs laid later in the day.

4. It may be more economic to use eggs laid from 14.00 to 17.00 h as table eggs rather than hatching eggs.     

Battery cage shape: Its effect on diurnal feeding pattern,egg shell cracking and feather pecking

1. Battery cages 460 mm in depth (deep) were compared with 305 mm cages (shallow); the two shapes provided equal areas per bird.

2. More eggs were produced per hen housed from 30 to 70 weeks in the shallow cages; the difference approached significance.

3. The pattern of feeding activity over the day was significantly more U‐shaped in the shallow cages; this pattern accords more closely with physiological requirements.

4. Feather damage caused by pecking was slightly but significantly more severe in the deep cages at 70 weeks.

5. The proportion of cracked eggs (collected from 60 to 70 weeks) was significantly lower in the shallow cages.

6. The arrangement of the hens was such that within the shallow cages a higher proportion of birds was present in the front half.

7. It is suggested that some of the advantages conferred by the shallow cage may be related to the greater accessibility of the food trough.     

Characterisation of tetra-nucleotide microsatellite loci in the ostrich (Struthio camelus)

1. Eleven polymorphic tetra-nucleotide microsatellite loci were identified in the ostrich (Struthio camelus) using a selective enrichment protocol.

2. The average number of alleles observed was 6·6 with an average heterozygosity of 0·4.

3. The population was found to be in Hardy-Weinberg equilibrium and two of the loci had a greater than 95% probability of having null alleles.

4. These microsatellite loci will add to the existing pool of markers available for the ostrich and help to facilitate analysis of population structure and pedigree determination.     

Whitening of brown shelled eggs: Individual variation and relationships with age,fearfulness, oviposition interval and stress

1. Fearfulness, shell colour, incidence and degree of shell whitening and the interval between ovipositions were studied in two populations of 30 brown egg laying hens with family histories of a low or a high incidence of egg shell whitening.

2. Hens of the population with the high incidence of whitening appeared to be more fearful than hens of the population with the low incidence of whitening.

3. Brown colouration of the egg shell and the incidence and degree of shell whitening declined as the hens aged.

4. Brown colouration and egg shell whitening were most pronounced on the blunt ends of the eggs.

5. A large part of the variation in egg shell whitening was attributable to the individual (hen) component of variance.

6. Differences in egg shell whitening, between the two populations, were detectable throughout the 26 weeks of the experiment.

7. Oviposition intervals were similar for normal and coated eggs when birds were not exposed to disturbance.

8. Disturbance of hens increased oviposition intervals and the incidence and degree of shell whitening, to a similar extent, in both populations.

9. It is concluded that stress‐related egg retention is not the sole factor responsible for abnormal egg shell whitening. Shell whitening may occur as a consequence of the premature termination of shell pigmentation as well as a consequence of the retardation of oviposition which occurs when hens are disturbed.     

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.     

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.     

Comparison of nutritive values of groundnut oil cake and Niger oil cake for laying pullets

1. The nutritive value of Niger oil cake (Guizotia abyssinica, Cass.) as a protein supplement for layers’ diets has been assessed.

2. Replacing groundnut oil cake (GNC) by Niger oil cake (NC) on an isonitrogenous basis, did not affect egg production, egg weight or the amount of food required per dozen eggs.

3. The percentage retention of nitrogen from diets containing 30% GNC or 30% NC was similar.

4. The ME value of NC used was 3025 kcal/kg.

5. It is concluded that NC can replace GNC in layers’ diets.