25 25 LOHMANN TIERZUCHT › MANAGEMENT GUIDE The Hatching cycle After the routine transfer from setter trays to the hatcher basket and relative hatcher machine, the embryos have to continue their natural development and prepare for the hard cycle of the hatch. The gen- eral climate conditions are very important because our embryos have to finalise the transformation of internal organs and pre- pare the piping and the relative exit from the eggs. In these last days, our embryos turn their body position along the long axis of the eggs, and by positioning the beak under the right wing, they are now in a perfect position. The yolk starts to retract in the abdominal cavity, and the navel starts to close. At the same time, blood circulation undergoes the necessary modifications. Now our chicks are ready…….. Turn the beak and start with the internal piping of membrane,continue with a circular cut of eggs relative to our external climate and conditions, keeping our internal condition liveability and perfect chick development (embryological time), we have start our hatch windows. Simple in this description but this is . . . the miracle of life. The phase during hatching is different, and we can help our chicks with different set stages. This is necessary in both phi- losophies of works, namely Single-Stage and Multi-Stage, because we can help a lot with the right action. Some brands of hatcher have some inter- esting tools to better follow the chicks’ condition, others believe more in different forms of control. Of course, carbon diox- ide is a sure value that can help reveal a lot about the real condition of our hatcher machine, in relation to the situation that we have done in a full complete cycle. Uniforming and stabilising the embryos’ time with the right condition and synchro- nising chronological and embryological time creates a very nice advantage. As mentioned in the previous chapter, in this guide we don’t want to suggest any dedicated programme, as the variability of and the differences between one hatcher brand and others need a dedicated inves- tigation and test, but an important target to consider is the right hatch windows time. Of course, depending on the age of the flock and the storage period , for a good chicks’ condition and forbest live- ability hatch window start with the first 5 % of chicksfrom thetotal chicks pull-out(it takes minimum26 to 30 hours for Single- Stage and 28 to 32 for Multi-Stage). Warning: the definition of hatch windows isn’t completely correct: in reality between 5 % and 98 % of chicks hatch, but it is impossible to have total control of every hatch basket in order to verify these pa- rameters without having a negative influ- ence on the climate of the hatcher, (the real hatch windows time in hours is short- er, but it certainly is more easy to calculate in the form described). Some new trends are just evolving: the hatch directly in a farm cage, or in special machines where the chicks hatch directly on the setter trays and can eat and drink as they need to. These arguments need a totally different discussion, which is more specific for each construction brand, which we don’t want to touch in this gen- eral guide.