In association with Poultec Training Ltd
Much can go wrong between the nest in the breeder house and the setter at the hatchery. Pas Reform’s Gerd de Lange looks at how to avoid these problems
Every unhatched chick represents a financial loss which can make the difference between profit and loss for the commercial hatchery.
One factor sometimes responsible for poor hatchability, and chick quality, is poor egg management after it has been laid. Effectively, the breeder farm manager may have done his job in producing a top quality egg, but all this effort can easily be undone by bad handling.
How do you get eggs out of the nests in "good shape"? Hatching eggs should be clean and undamaged. Contaminated hatching eggs are a source of infection, which not only affects hatchability and chick quality, but also the first-week mortality and reduced performance in the receiving farms.
Therefore, good nest hygiene should be maintained at all times. Close the nests during the night, to prevent birds soiling them, but ensure timely opening again the next morning to prevent floor eggs.
Floor eggs, even when they look clean, should be collected separately and not used for incubation. The incidence of "bangers" – eggs that explode in the setter or hatcher due to pressure-build up by gas-producing bacteria or aspergillus (fungi) – is much greater in floor eggs than in clean nest eggs.
Eggs with hair cracks (thin cracks in the shell) allow bacterial penetration and tend to dehydrate during incubation. Both will have an adverse effect on hatchery results. Hair cracks can happen due to either too many eggs in a nest or on the egg transport belt, causing the newly laid eggs to bump into each other.
More frequent collections will help cut the incidence of hair cracks. Further avoidance can be achieved with well-designed trays that support the eggs. Handling the eggs with care at all times will avoid hair cracks and also prevent damage to the delicate embryo inside.
What is egg storage?
Egg storage is the timespan during which hatching eggs are kept between laying and the start of the incubation process.
Several phases are recognised during this period of "storage", namely the time the eggs are kept in the nest or on the egg transport belt in the breeder house, the storage period at the breeder farm, the time during which the eggs are transported to the hatchery and lastly the storage period in the hatchery.
When a hatchery manager speaks about a batch of eggs stored for six days, he could mean several things, including:
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This batch of eggs was produced six days ago.
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The oldest eggs in this batch were produced six days ago.
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This batch of eggs was stored in the hatchery for six days (without reference to storage time at the breeder farm).
To avoid any miscommunication, it is advisable to label each batch of eggs with the actual date of production. From an egg management point of view, the time the eggs are kept in the nests or on the egg transport belt in the breeder house is also important.
How often should eggs be collected?
Although the exact level of the so-called "physiological zero" is debated by hatchery specialists and researchers, there is a general consensus that embryonic development, which starts in the hen’s body, will continue as long as internal egg temperature is more than 25-27C.
Ideally, eggs should be cooled down uniformly and gradually from body temperature to between 18 and 25C in 6-8 hours.
However, eggs produced in manually-collected litter nests cool down very slowly, due to the insulation provided by the surrounding nest litter. Since nest boxes are shared by five to seven hens, warmth is brought to partially cooled-down eggs every time another hen enters the nest. It is only once the eggs are collected, that they are able to cool down properly.
In automatic nests, the eggs roll away to an egg transport belt soon after being laid, which exposes all the eggs to a similar environmental temperature. Too far advanced embryonic development should be avoided to prevent increased mortality during storage and early incubation. Therefore, collect eggs from manual litter nests at least four times a day, and from automatic roll away nests two to three times a day, ensuring that the temperature on the egg transport belt is a constant 18-22C.
An adequate supply of circulating air over the trayed eggs will greatly assist in providing uniform cooling. This is achieved by collecting the eggs on setter trays.What are the effects of egg storage on hatchability and chick quality?
The graph shows the results of a recent epidemiological study on Dutch hatchery data from three broiler hatcheries during 2004, 2005 and 2006.
The decrease in hatchability is between 0.2 and 0.8% a day of storage, with greater effects showing the longer the eggs are stored.
Contrary to common belief, data show that younger flocks are more sensitive to storage than older flocks. The total loss in hatchability is thus quite considerable and can easily reach 5% with 10 days’ storage. It also revealed higher first-week mortality in the broiler farms as a result of prolonged storage. Day-old-chicks from stored eggs show a higher incidence of "black navels".
Studies show that pre-incubation egg storage has a negative effect on hatchery success. To reduce this, it helps to avoid long storage periods as much as possible by applying the "first in, first out" principle.
Optimum storage conditions depend on the number of days the eggs are to be stored (see above); lower temperatures are required for eggs that will be stored for longer periods. If eggs are transported to the hatchery twice weekly, the farm store should be kept at a temperature of 18-21C, to minimise the risk of eggs "sweating" during loading of trucks in summer.
Often storage time varies for all batches of eggs, so it’s beneficial to retain at least two separate storage rooms, where climatic conditions can be maintained accordingly.
Relative humidity should be kept high to minimise weight loss, but not so high that it stimulates bac-terial and fungal growth. Care should be taken to ensure that humidifiers do not wet the eggs, as this promotes bacterial penetration.
If eggs must be stored for more than 10 days, it is advisable to store them small end up. Importantly, though, eggs should never be transported in this position, as this will result in so-called "loose air cells". Equally, when eggs are stored on setter trays, storing small end up is not practical. Alternatively, turn the setter trays over 90° every 24 hours during storage.
Stored eggs require one extra hour of incubation time for every day over three days. To avoid a long hatch window, do not place batches of different storage duration in the same setter.
Lastly, pre-warming, bringing the egg and its contents to a uniform temperature of 25C immediately prior to incubation, partially offsets the negative effects of long storage..
Gerd de Lange is the senior poultry specialist at Pas Reform Academy
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