Table 9.

Developed scoring system for the evaluation of the level of visible external contamination as indicator for the microbiological contamination level.

Score	Appearance of Feathers/Coat	Score #	Dirt/Fecal Contamination
0	Chickens have a fluffy appearance with dry (white *) feathers.	0	There are no or at least very few small visible contaminations on the feathers or the breast skin.
1	Chickens still have some fluffy appearance with mostly dry (white *) feathers. Only some feathers are wet or slightly discolored.	1	There are few small contaminations of the feathers and the breast skin with only 1–2 large loosely attached contaminations on the coat.
2	There are wet or discolored feathers but mostly around breast skin area. Some of the feathers appear separated.	2a	Chickens are obviously contaminated on the breast skin and/or the coat (mainly small contaminations)
3	Large areas of the coat have wet or discolored feathers. Most of these feathers appear separated.	2b	Chickens are obviously contaminated on the breast skin and/or the coat (mainly large loosely attached contaminations)

* In case of Ross308; # categories 2a and 2b were calculated as 2 in the final scoring.