A key area for performance losses in the hatchery is often seen with increased egg age, especially for breeding Grandparent and Parent Stock operations. For most operations, egg age is ideally under 7 days of age, but with variations in orders, production volumes with different size farms and market/seasonal conditions increased storage time can be inevitable. Effects from increased egg age can result in reduced hatchability and chick quality levels, increased incubation time and adverse broiler performance (7 day mortality %) with poorer viability of the chicks as seen in Fig. 1 from studies by Reijrink 2010. The following graphs from Tona 2003 shows the effect of increased egg age delaying hatching times from eggs stored for 3 days and 18 days (Fig. 2) and the impact on broiler bodyweights from fresh eggs compared to eggs stored for 7 days (Fig. 3). During storage, the characteristics of the egg yolk and albumen changes in the following ways: • Carbon dioxide and hydrogen levels deteriorating • Changes in the yolk pH values from 6.0 to 6.5 • Albumen pH values increase from 7.6 to 9.0 • The yolk sac membrane loses rigidity and becomes more elasticity • Lower albumen heights (Haugh height) When the hen lays an egg, there are potentially up to 60,000 live cells, but these cells die off rapidly during storage. The photos below show a blastogerm with the live cells in the photo (left) and a blastogerm with reduced live cells in the photo (right) (Fasenko). The table below the images shows the effect on live cells with egg storage (Baskt). Over the years many techniques have been applied to minimize losses from increased egg age. They include: • Turning eggs in storage • Use of ‘buggy bags’(covering eggs with plastic bags) to minimize gaseous exchange • Storing eggs upside down • Flushing eggs with nitrogen • High CO2 during storage • Low O2 during storage • Reduced storage temperatures • Slow warming profile at the start of incubation • Heat treatment of hatching eggs during storage Pre-incubation During Storage Although there has been increased publicity on this method in recent years, the practice is not new with research conducted in Israel several decades ago. Cobb has been using this practice in Brazil for many years with success. Cobb has called this ‘Heat treatment of hatching eggs during storage.' Method – (Example eggs expected to be stored for 10 days before setting) 1. At 5 days of storage (from day of lay) remove eggs from the egg room to an operating setter with a temperature of 37.5°C (99.5°F). 2. For multi stage setters place the trolleys of eggs in the central corridor and for single stage setters ensure the empty machine is achieving the above temperature before placing inside the cabinet. 3. Leave the eggs in the setters for 4 to 6 hours (Need to achieve eggshell temperatures of 32°C (90.0°F) from all tray positions). 4. After this period, remove the eggs into the setter room corridor to cool down to 25°C (77.0°F) for approximately 2 hours. 5. After this period return the eggs to the egg store until they are needed for setting. Be aware of these eggs increasing the temperature in the egg store and causing sweating!! A normal hatching egg received at the hatchery will be in the embryo germinal disc stage 10 (EG10). After the egg has been laid and cools down, embryo development is suspended below 24.0°C (75.0°F). By applying this heat treatment process, the embryo germinal disc advances to stage 12 or 13 (ED12/ED13). When the eggs are used for orders and placed in the setters, the embryo is better prepared for development and successful hatching. If the heat treatment process is for too long, the ‘primitive streak’ will be developed and the incubation process needs to be continued, as this is the point of no return and embryonic losses will occur. Results At Cobb Europe we have conducted some recent trials on our female lines with the following results – Not only did the trials show an improvement in hatchability, but also in chick quality. Summary Heat treatment of hatching eggs during storage can increase hatchability by over 2.0% or 1.4% usable product as seen by Cobb Europe. • Do not heat treat for long periods (over 6 hours) • Ensure eggshell temperatures of 32.0°C (90.0°F) in the incubator are achieved for optimum results.