When a problem occurs in hatchability, usually it can be categorized as a hatchery, egg handling, or breeder flock problem.
If the problem has originated within the breeder flock, it is probable that it happened at least 6 weeks earlier, assuming 5 weeks of incubation and 1 week of egg storage.
This delay in identifying a problem is costly and may even make it impossible to determine the cause if the effect is of short duration. It is necessary to identify the problem as early as possible, using candling at 2 week of incubation and constantly monitoring unhatched eggs, to minimize the delay in taking corrective measures. Analysis of hatch debris does not yield definitive diagnoses.
Many factors can affect the hatchability, including health of the breeders, Derszy disease, feed quality, etc... But if you have a problem with Derzsy or health of breeder, you will be able to observ these problems on egg production rate at first.
So, do you have specific problems in egg production rate on your breeder?
In addition, your fertility should be also affected if you had health problems on the breeder ducks, and it seems that you have no problem on fertility at this moment. At this stage, and with the problem on hatchability only as we can see. We can think mainly about problems with incubation and hatching.
1st hypothesis: Humidity level in your setters:
The problem of late mortality on embryos is generally due to a problem in humidity management during incubation. It would be interesting to check again on your side, on automatic controls and on manual controls (wet bulb thermometers) if your humidity rate in setters is right or not!
In addition, and still in order to control the right level of humidity in your setter, we can strongly suggest you to check the egg weight loss on eggs during incubation.
For that, you have to weight 3 or 4 egg trays of each flock of origin before incubation and every week during incubation, always at the same time every week, in order to check the egg weight loss during incubation.
In Muscovy ducks, the eggs should loose 2,8% of their weight regularly every week of incubation.
If the eggs loose less weight than 2,8% every week, it means that the humidity is too high in your setters. If the eggs loose more weight than 2,8% every week, it means that the humidity is too low in your setters.
In both cases, the ducklings will be weak at the end of the incubation period, and they will not be able to pip the eggs, or they will not be able to hatch even if they start piping their egg shell. You could have good control of humidity before, and now, because of change of temperature or humidity in the climate, it could have some big influence on the situation of humidity in your own setters. That's why it is normal to adapt the humidity sometimes in your setters, according to the season.
Other hypothesis: Humidity in your hatchers:
Wrong humidity in your hatchers can also explain this type of situation. For that, you just have to check your equipments in order to be sure that they are in good order.
Of course, you can not control the egg weight loss during this stage.
By weighing the eggs, you could be able to adapt the right humidity rate in your setters within 2 or 3 weeks of control of egg weight, and come back then to the right humidity parameters and right hatchability rate after these 3 weeks of control. It means that, if the problem is really coming from a wrong humidity rate in your setter, you could come back to better results in hatchability within 4 weeks from now, if you start of course very soon the egg weight control.
The Process of Artificial Insemination in Ducks
1 - Semen Collection and Processing
2 - Insemination