I recently received an alarming email from one of our customers, which read: “We had a very bad 18 days transfer yesterday and the entire setter has been affected by early deaths, ranging from one to three days of incubation.” Photos of setter trays full of clears on a candling table and of the same setter trays with opened eggs showing early signs of embryo development demonstrated the horror scenario that had taken place in this normally successful hatchery. Something had gone dramatically wrong, but what?

The first thing I did was to remotely log into the customer’s hatchery management system and check the setter’s climate history. The climate graph looked fine; the only abnormality being that the CO₂ level was low throughout the entire period. I then checked whether something strange had happened during the pre-heat phase, and it had! The pre-heat for this incubation cycle was normal, although perhaps a little longer than necessary, with 12 hours at 77°F. However, 24 hours earlier, a pre-heat in the same setter was followed by barely one hour of heating to incubation set point, after which the set point temperature was reduced to 65°F. Was it possible that the setter had been loaded and accidentally started a day early, and that somebody had tried to keep their mistake quiet? On the other hand, it is not very likely that such a mistake would cause 95% early mortality. Perhaps the setter had been empty and they were just testing it before loading.

I decided that the best course of action was to set up an online meeting with the hatchery manager to discuss my ideas, and, indeed, my first question was a direct hit! When I asked him whether they fumigate eggs with formalin, he told me that this was normally only done at the breeder farm. I asked him what he meant by ‘normally’, and he said that a consultant recently visited his hatchery together with his boss. In the transfer room, the consultant suggested first marking the clears on the candling table before taking them out, to increase the accuracy rate. The hatchery manager was not very happy about this, as it would almost double the transfer time, but his boss insisted that he follow the consultant’s advice.

There were a few bangers during transfer, but nothing alarming according to the hatchery manager. However, this was reason enough for the consultant to advise the weekly boiling of liquid formalin in an electric pan in the air handling unit to treat the entire setter air distribution system. The affected setter was at that point in its first day of incubation and, despite the fact that the dampers were closed, enough formalin entered the setter to do its damaging work. It is known from the literature that embryos are extremely sensitive to formalin during the first 96 hours of incubation, and all contact should therefore be avoided. Luckily, the hatchery manager – who already heavily doubted the consultant’s advice but didn’t want to displease his boss again – did not repeat this formalin treatment. He had noticed that, prior to the reported issue, hatches had dropped by up to 3%. With an apologetic look on his face, he admitted that he had sent his email to test whether his conclusion made any sense. I confirmed his suspicion with a whole-hearted “Yes, it does”, and luckily the next hatches were back to normal.