fresh hatching eggs

candling eggs at 7 to 12 days

breakout comes at hatch time

the quickest way to estimate fertility

1- a flock begins to lay eggs

2- a flock has been treated for a disease

3 - fertility problem

only provides information on fertility estimates

the loss of valuable hatching eggs

the sample size rarely exceeds 100 eggs, resulting in the third disadvantage errors of prediction.

it is more difficult to distinguish between fertility and infertility in fresh eggs

Shape: Upon close observation, a blastoderm (indicating fertility) is always round (i.e. almost perfectly uniform and symmetrical). Hatchery personnel often refer to this shape as a "doughnut." The doughnut appearance is seen as a white symmetrical ring with a clear area in the center of the ring (Plate 1). Sometimes a white dot will be present in the center of the clear area. The blastodisc (indicating infertility) is rarely perfectly round, and has jagged edges. There are usually more vacuoles (bubbles) present in the periphery of the blastodisc than the blastoderm (Plate 2).

Size: The blastoderm is almost always larger

in appearance (one- quarter to one-third

larger) than the blastodisc.

Color Intensity: The blastoderm almost

always appears to be a less intense color of

white than the blastodisc. The blastodisc

appears as more of a small, intense white

spot on the surface of the yolk. Sometimes

the blastodisc is granulated. Instead of one

white spot, there may be several clumped

white spots

it is important to have a sample size of at

least 100 eggs per flock. Because of the

disadvantages involved in the fresh egg

breakout, this procedure is not

recommended unless a quick fertility

check is desired.

offers the most accuracy in determining

fertility

determining other sources of breeder

flock or hatchery failures, such as

percentages of eggs set upside cracked

and embryos that have died early

can be done as early as 5 days of

incubation but with errors to consider

candling errors are made on the 9th or

10th day of incubation is few if any

The fastest method involves the use of a table or mass candler.

Clear eggs consist of infertiles

eggs with early dead embryos and emit more light than eggs with viable embryos

Candling with a spot candler

little slower, but more accurate

less candling errors are committed and eggs set upside down or cracked are much easier to distinguish

eggs set upside down

farm cracks

cull eggs

hatching eggs with the blunt end up cost the company a lot of money in lost hatchability and chick quality more important in hatcheries using in ovo vaccination. Practically, all the embryos contained in upside down eggs will be killed

a sufficient sample size of eggs must be used for candling.

A minimum of four trays per breeder flock is needed to ensure that estimates for fertility, eggs set upside down, farm cracks, and cull eggs are meaningful

Take eggs from different areas of the incubator racks/buggies. This will provide a more random sample which is desirable.

It is often suggested that candling

estimates of fertility are the "true fertility."

This is not correct. Candling samples of

eggs only provide an estimate of true

fertility

The only way to obtain the information of

true fertility would be to candle every

tray In a setting of a breeder flock

You may be throwing away valuable information in

your hatchery waste that could help solve hatchery

and breeder flock problems, or improve hatchability

and profitability. Unhatched eggs hold information

that breeder and hatchery managers need. Without

breaking eggs to gain this information, reasons for

moderate to low hatchability are only guesses

The hatch day breakout analysis involves sampling

unhatched eggs from breeder flocks, and

classifying them into the various causes of

reproductive failure. The procedures for this

valuable management tool are described below

should be performed at least once every two weeks on samples of eggs from all breeder flocks regardless of hatchability performance or flock age

Even good hatching flocks should be monitored to get a true picture of hatchery and reproductive efficiency

Breakout analysis on all breeder flocks is critical in pinpointing problems in setters and hatchers

Breakouts are also beneficial for trouble-shooting problems in production, egg handling and storage.

For example, high numbers of early deads may indicate prolonged storage or storage at elevated temperatures, or inadequate egg collection procedures. In most hatcheries, the breakout should be performed on two consecutive hatch days to ensure that all breeder flocks are sampled.

Immediately after the chicks are pulled, collect a minimum of four trays of eggs per breeder flock from different parts of a single setter.

Remove all unhatched eggs, including pips, from the hatching tray. Place them in filler flats with the large end up and record the flock number.

It is best when the breakout is done soon after the hatch rather than a day or two later. This gives a more accurate estimate of live versus dead in shell.

Record the number of cull and dead chicks left in the tray.

Break out the eggs and classify them into the appropriate categories of reproductive failure listed in Table 2 and Table 5.

The best procedure is to break and peel the large end of the eggs since embryonic development will most often be located there.

The alternative method of cracking the eggs over a pan is not as accurate because the embryo or germinal disc often rotates beneath the yolk and is difficult to locate. Cracking eggs also increases the likelihood of rupturing the yolk membrane (these membranes are weak after 21 days of incubation). When the yolk membrane ruptures, it is difficult to know if that egg contained an early dead embryo or was infertile.

There are some cases when the embryo or the blastodisc

will not appear on the top of the yolk. When this occurs,

rotate the egg and pour off some albumen so that the

germinal disc (fertile or infertile) will appear at the top. If the

embryonic development is still not found, the yolk may then

be poured into an empty pan and examined.

The classifications of embryonic death may be as detailed

as the hatchery manager wishes. It must be kept in mind

when starting a breakout program that the quality control

person need not be an embryologist. In most cases,

sufficient information is obtained by classifying the dead

embryos by the week that death occurred (i.e., first, second,

or third). This is easily done after a few practice runs.

The clarity of the development is not as good in eggs broken after 21 days of incubation as when eggs are broken while the embryos are still alive. However, with practice one can conduct an accurate breakout analysis by judging the embryos according to size and looking for some of the obvious changes in the developmental sequence (Table 3).

A good training technique for someone not previously involved in breakout analyses would be to examine live embryos at different stages of development and compare them to the dead embryos obtained from unhatched 21-day incubated eggs

Fertility of a 21-day incubated egg can be identified by looking for signs of development and by examining yolk color and albumen consistency. The two statements that follow relate to the identification of very early deads, positive development, and infertile eggs after 21 days of incubation. Generally speaking, an infertile yolk will be a brighter yellow than a fertile yolk. The albumen of infertile eggs is thicker than the albumen of fertile eggs. An infertile yolk is held in the center of the egg while a fertile yolk will sink near the point end.

Although these statements are correct, there may be instances when they are not fail safe. To accurately classify the egg, the presence or absence of early embryonic development must be established. Most eggs can be classified as soon as the tops of the shells are peeled back. Others require closer inspection. Be careful not to let blood spots, meat spots or yolk mottling result in classifying an infertile egg as fertile. Another pitfall is that most embryos that die during the second week of incubation look dark and are often mistaken for contaminated eggs. The dark appearance results from the breakdown of the blood in the tremendous vascular system of the extra-embryonic membranes. Most contaminated eggs will be malodorous which will help to classify them. Second week embryonic mortality may look contaminated; however, they should only be classified as contaminated when they emit an odor.

The sample index listed in Table 5 is a valuable measure of how representative your sample is of the true reproductive performance of the entire setting of eggs. A large sample index (greater than 3.0) would indicate that the sample was not a good representation of actual performance. Small sample sizes will result in greater variation in the sample index. Calculating these measures is necessary in interpreting results and taking corrective action. It would be a mistake to take corrective management changes in the flock or hatchery due to break-out analysis results when the sample index is high

Parameters %

Hatch 85

Second quality

chicks 1.0

Dead chicks 0.25

Pipped eggs 1.25

Infertiles 4.50

1–4 2.50

5–10 1.25

11–17 1.25

18–21 2.50

Contamination 0.50

Total 100.00

Table 1.

Egg break-out data for 40 week production cycle.

Evaluating three trays per breeder farm on a weekly basis is recommended.

A representative sample, with each tray separately identified, should include one tray from the top, one from the middle, and one from the bottom of one buggie per farm.

The three tray samples must come from the same farm and egg collection day to allow comparisons to be valid

plan of Action Egg breakout analyses must be conducted in an orderly sequence as follows:

Communication: Maintain channels of communication among breeder, hatchery, and broiler personnel and employ simple language to be understood by all.

Be prepared:

The hatchery manager should schedule the farms for the breakout analysis in advance and note the location of the eggs.

The data sheets should be available and ready to be filled out with the necessary background information.

The minimum data required are age of the flock, breed cross, health status, type of machines used to incubate the eggs, and duration of egg storage.

Vital data: After locating the three preselected trays from a specific breeder flock for breakout analyses, the following information for each tray must be recorded on the data sheets.

% hatch for the lot

% hatch for the three trays selected

Total number of eggs per tray selected

Number of healthy chicks

Number of dead chicks

Number of second quality chicks

Number of exploders

from the selected hatch trays, collect the remaining pips, unhatched eggs, and dead chicks. Place the eggs with the large end up in egg flats, and count and record the number of dead chicks. The three flats must be identified as to breeder flock and hatcher tray position. The following steps should be taken to minimize errors and confusion when collecting and analyzing data.

Count the pips. Remove the shell cap and determine the reason for not hatching. Record observations and comments. To facilitate the process, an assistant may record the findings.

With a spoon or forceps, gently open remaining eggs at the large end.

Remove the eggshell cap and shell membranes with care. The blastoderm or very small embryo may adhere to the inner air cell membrane and be inadvertently discarded. These eggs may be mistakenly classified as infertile.

After opening and examining the unhatched eggs, tabulate and classify the findings into the following categories:

infertile

embryonic mortalities at 1–7, 8–14 and 15–21 days of incubation

contamination.

After classification, discard the eggs.

At each stage ensure that all eggs are counted and

classified, and the information is recorded on the data

form.

When conducting the breakout analyses, it is not

necessary to remove the egg contents unless there is

doubt as to the reason the embryo was unable to

hatch.

Most commonly, eggs that do not hatch fall into these

categories: infertile, deformed, dehydrated,

malpositioned, contaminated, oversized embryo, etc.

A common technique is to display a reference poster in the work area which has high quality scale photographs of the embryo and chick at progressing stages of incubation. These posters may be obtained by contacting incubator manufacturing companies. It is also recommended during the learning process to open eggs at various incubation ages to learn how a normal growing embryo develops on a daily basis.

Key distinguishing features: 7–8 days of incubation—eyes can be distinguished.

13–14 days—feathers have started to develop.

15 days—all structures of the embryo have been formed, the embryo is now increasing in size and positioning for hatch

In many cases, it is difficult to accurately distinguish among eggs that are fertile, eggs that are infertile or eggs that exhibit positive development when analyzing hatch residue. To increase accuracy of findings, it is recommended to candle the eggs at 9 to 12 days of incubation in the setter, when it is easier to distinguish fertile and infertile. The percent of infertiles and early deads obtained at this stage can be used as a standard at hatch time when the egg breakout is conducted for the same batch

After conducting break-out analyses at an operation and developing a data base, standards for various categories may be generated based on local factors such as breed types, fertile egg source, and feeding and incubation equipment. In hatcheries, three standard tables are commonly developed that take into account the age of the breeders. This variable has a major impact on percent hatch, infertility, and embryonic mortality. The three age periods are usually 25–35, 36–55 and 56–65 weeks. The most dramatic differences in these tables, based on increasing breeder age, would involve percent infertility, second quality chicks and contamination related to egg shell thinning.

Hatchability has been declining over the last several years as reported by hatcheries throughout the world. This decline has been related to the recent emphasis on aggressive genetic selection for the characteristic of breast yield over other criteria. However, some deviations in hatch have nothing to do with genetics, but with how we produce, manage and incubate the eggs.

Routine egg breakout analyses provide information to enable a manager to determine where problems are occurring and allow timely resolution. Some common causes of hatch failures are described below. A more detailed listing is available in many textbook and hatchery guides.

High infertility: due to

impotent males,

unreceptive females,

incorrect male to female ratios,

mycotoxins in the feed,

sexual maturity delays,

feed imbalances,

high stocking densities,

poor ventilation,

overweight breeders,

lighting problem, etc.

Elevated embryo mortality between 1–4 days of incubation: due to

egg management,

egg room temperature and relative humidity

duration of egg storage,

sperm age and quality.

Elevated embryo mortality between 5–18 day of incubation: due to

machine management,

egg turning,

too high or low temperature and relative humidity.

Increased dead in shells: due to

poor ventilation in the hatcher,

malpositioned embryos,

poor ambient conditions.

the focus must be on hatching the

maximum number of eggs

the percent of cull fertile eggs should not

exceed 4.0% during a 40-week

production cycle.

Table below shows the percent of the various

categories for cull eggs during 40 week

production cycle

less restrictive egg selection could be practiced.

The 4% total cull eggs can be reduced to 2.5 to 3.0%.

This can be achieved by decreasing the number of cracked eggs, by saving the mildly deformed and porous eggs, and by reducing minimum egg weights for incubation.

Many hatcheries perform a simple breakout analysis,

identifying and recording infertile eggs and early, mid

and late deaths .

This analysis is generally more than sufficient, offering

indicators as to the area that needs further investigation

or a conformation of the current performance.

In a more precise analysis, also called a localised

breakout analysis, chick malformations and positioning

problems are also recorded, providing more adequate

clues regarding the specifc area of concern

If the localised breakout reveals many

problems regarding the chick’s

position or location within the egg,

there are issues in the mid and late

developmental stages.

An increased level of malformations

indicates problems during the early

phases of incubation.

Simple hatch debris analysis

step 1: sample selection and preparation. • hatch debris breakouts should be integrated with other QA procedures such as measuring egg water loss and chick yield. • Monitor three setter trays per flock per week, and label sample trays clearly at the time of set. • The eggs used for the sample trays should be clean nest eggs of known flock source, flock age and egg age.

Clear or non-viable eggs should not be removed from trays. However, it will not be possible to distinguish infertile from early embryo mortality on clear eggs left in the setter for 18 days. A separate sample of eggs should be used for fertility identification (see ).

step 2: Take off and count dead in shell. • On the day of hatch, count chicks and culls out of the sample setter trays. Record their numbers per tray. • Collect, count and separate out the unhatched (dead in shell) eggs. Record their numbers per tray.

Note: The totals for chicks plus culls and dead-in-shell should equal the number of eggs set, less any removed at candling. step 3: Breaking out dead in shells.

• Identify and count any eggs where the beak has pierced the shell (pips). Record numbers, and note if any chicks are still alive.

• Open all the eggs, at the air cell. Take care not to remove any egg contents when lifting the air cell membrane.

• Identify the stage of development of the embryo and sort eggs into groups of infertile, early dead (0-7 days) mid dead (8-15 days) and late dead (15-21 days) using the pictures on page 3.

• Check very late (20-21 days) dead embryos for malpositions

• Check for malformations in the mid and late dead embryos.

• Also record any with cracked or poor quality shells and any eggs that are contaminated.

The incidence of Malposition3 (Head turned to left) and Malposition 5 (Feet over head) is normally 0.25% of eggs set (each).

The incidence of Malposition 6 (Beak above right wing) is normally about 0.4% of eggs set

Head in small end of shell (Malposition 2) is the most variable malposition as it caused by setting eggs upside down. The occurrence of this malposition should not exceed 0.1% of eggs set.

Occasional abnormalities are not a

cause for concern. Further investigation Is

appropriate only if a single malformation

occurs at levels over 0.5% of the eggs set.

Tray No. 1 2 3 4 5 6 7 8 9 10 To

tal % of

eggs set

No. of eggs removed

Infertile

“Early Dead“ (0-7 days)

“Mid Dead” (8-14 days)

“Late Dead” (15-21 days)

External Pip

Dead and Cull Chicks

Contaminated

Poor Shell Quality

Cracked Shell

Malpositions - Head in small end of egg

- Head to left

- Feet over head

- Beak above right wing

Malformations - Exposed brain/Eye defect

- Extra limbs

- Ectopic Viscera

Embryo - Wet

- Dehydrated

Notes:

Joseph M. Mauldin, Extension Poultry

Scientist at the University of Georgia

Gary D. Butcher and Amir H. Nilipour

Aviagen publications