Transparency

Transparency is a means of identifying unfertilised and prematurely dead embryos. The egg trays are passed over a powerful light source which clearly shows unfertilised and prematurely dead embryos. Transparency is not systematically carried out in all hatcheries, as it requires additional equipment and labour. However, we recommend candling a sample from each batch every week to monitor the condition of the breeding stock. If the percentage of candelabra exceeds 10%, then all eggs should be candled, clear eggs removed and incubator trays filled to 95-100%. This will improve the technical results.

Candling is usually carried out between days 9 and 10 or as part of the transfer routine. When carried out during transfer, an automatic candelabra machine with an egg remover is often used to keep pace. These machines are quite expensive and are not cost-effective for small hatcheries. A table candelabra, which illuminates an entire incubator tray from below, is used in many hatcheries. A spot candelabra is ideal for candling samples. This is by far the cheapest and most accurate method, but it does require some training and is more time-consuming when large volumes are involved.

If transparency is combined with the separation of clear eggs, this is the best method for identifying fertility (see the ‘Separation analysis’ section for more details). Upside down eggs, cracked eggs and other second quality eggs can also be noted at this stage. Such transparency analysis can be an important part of a hatchery’s quality control programme.

Transfer

Incubation trays are designed to maximise the number of eggs that can be placed in an incubator and to allow easy turning of the eggs. However, they are not suitable for hatching, simply because the chicks would fall off the trays. Therefore, the eggs are removed from the incubator after 18 to 18.5 days, transferred from the incubation trays to the hatching baskets and placed in separate hatching cabinets. In this way, the transfer helps to keep the large amount of down generated during hatching away from the clean areas of the hatchery.

When different batches of eggs are placed in the same incubator, it is advisable to separate them when transferring them to different hatcheries (machine capacity permitting). This will harmonise the hatching process, reduce hatch dispersion and improve chick quality. However, a completely filled hatchery with different batches of eggs is preferable to a partially filled hatchery.

During transfer, it is very important to ensure a smooth process. Staff must understand that the growing chick has used calcium from the shell for its growth and that shells are very fragile at this stage. Don’t expect to get a chick from an egg that has cracked.

The temperature in the transfer room should be at least 25°C / 77°F and no trolley should be out of an incubator for more than 30 minutes. If the transfer is well organised, each trolley (around 5000 eggs) can be completed in less than ten minutes. This avoids excessive and uneven cooling of the eggs, which would increase the dispersion of the hatch. Of course, the transfer should only be carried out in clean, warm and dry hatching baskets and hatching cabinets.

• 1. Not all light-coloured eggs are infertile. You need to open the eggs to differentiate between infertile eggs and very early dead eggs.
• 2. Candling, removing clear eggs and refilling trays are recommended if the percentage of clear eggs exceeds 10%.
• 3. The temperature of the transfer room must be at least 25°C / 77°F.
• 4. Egg candling and transfer should not take longer than 30 minutes per trolley.
• 5. Only transfer eggs to a clean, dry, disinfected and heated hatchery.
• 6. Prefer to set only one batch of eggs per hatchery.
• 7. Set only one batch of eggs per hatchery.
• 8. Baskets are best heated inside the hatchery and removed directly before use.