Carla van der Pol M.Sc.

Floor eggs
Floor eggs are eggs that were laid outside of the breeder flock’s next boxes in loose housing systems. The eggs are often laid on dirty litter or other contaminated surfaces.
When an egg is freshly laid, it still has a temperature equal to the hen’s body temperature. It will cool down as it comes into contact with the cooler air and surfaces surrounding it in the breeder house. This causes the egg contents to shrink, pulling in air from the surroundings through the egg pores. The cuticle at this point is still soft and can be penetrated by more harmful material than outside air. Therefore, when a warm, fresh egg is laid on a dirty surface, contaminated
material may be drawn into the egg as it cools down. As a result, floor eggs have a higher bacterial load than nest eggs. They constitute a hygiene problem both within the hatchery and in the broiler house and would best be discarded. This may seem to be an economic loss, but discarding
floor eggs is beneficial to a hatchery’s quality standards and profitability. This article aims to explain why we believe that floor eggs are not hatching eggs.

Cross contamination
Van den Brand et al. (2016) demonstrated that hatchability was lower for floor eggs compared to clean nest eggs. This was due to lower fertility, higher embryonic mortality in the first and second week of incubation, and a higher percentage of rotten eggs. Not only floor eggs themselves
are affected by the higher microbial load, but they can also cross contaminate other eggs and hatchlings, especially those present in the same incubator. The most visual example of this are the so called ‘bangers’ or ‘exploders’. These are eggs in which the rotting process has caused hydrogen sulphide to build up, but it is contained by the eggshell and inner eggshell membranes.
The egg contents may leak through the pores and at a small provocation, the eggshell and membranes may burst like a balloon, directly contaminating neighbouring eggs with a spray of rotten egg contents and indirectly contaminating all other eggs inside (and sometimes outside) the incubator with airborne pathogens

Yolk sac infection
Those chicks that do hatch from floor eggs have on average a lower body weight than chicks from clean eggs (Van den Brand et al., 2016). Furthermore, they may contribute to post-hatch contamination of other chicks. Deeming et al. (2002) found that microbial yolk sac contamination in embryos that had died during incubation was three times as high for floor eggs as it was for nest eggs. Since they used eggs with intact eggshells, this suggests that microbial penetration of pathogens through the eggshell into the egg contents does take place and embryos can already be
affected during incubation. Since yolk sac infections are a major cause of early life mortality in broiler chickens, it can safely be assumed that a higher contamination in the egg can also result in higher mortality in the broiler house. Especially...